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1.
Org Biomol Chem ; 21(42): 8535-8547, 2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37840474

RESUMO

We describe the synthesis of trihydroxylated cyclohexane ß-amino acids from (-)-shikimic acid, in their cis and trans configuration, and the incorporation of the trans isomer into a trans-2-aminocyclohexanecarboxylic acid peptide chain. Subsequently, the hydroxyl groups were partially or totally deprotected. The structural study of the new peptides by FTIR, CD, solution NMR and DFT calculations revealed that they all fold into a 14-helix secondary structure, similarly to the homooligomer of trans-2-aminocyclohexanecarboxylic acid. This means that the high degree of substitution of the cyclohexane ring of the new residue is compatible with the adoption of a stable helical secondary structure and opens opportunities for the design of more elaborate peptidic foldamers with oriented polar substituents at selected positions of the cycloalkane residues.


Assuntos
Aminoácidos , Ácidos Cicloexanocarboxílicos , Aminoácidos/química , Peptídeos/química , Estrutura Secundária de Proteína
2.
J Org Chem ; 88(13): 8093-8098, 2023 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-37311064

RESUMO

The synthesis of a range of loline alkaloids is reported. The C(7) and C(7a) stereogenic centers for the targets were formed by the established conjugate addition of lithium (S)-N-benzyl-N-(α-methylbenzyl)amide to tert-butyl 5-benzyloxypent-2-enoate, ensuing enolate oxidation to give an α-hydroxy-ß-amino ester, and then formal exchange of the resultant amino and hydroxyl functionalities (via the intermediacy of the corresponding aziridinium ion) to give an α-amino-ß-hydroxy ester. Subsequent transformation gave a 3-hydroxyprolinal derivative which was converted to the corresponding N-tert-butylsulfinylimine. Mannich-type reaction with the enolate derived from O-Boc protected methyl glycolate then formed the remaining C(1) and C(2) stereogenic centers for the targets. The 2,7-ether bridge was formed by a displacement reaction, completing construction of the loline alkaloid core. Facile manipulations then gave a range of loline alkaloids, including loline itself.


Assuntos
Alcaloides , Alcaloides de Pirrolizidina , Oxirredução , Estereoisomerismo
3.
J Nat Prod ; 85(7): 1872-1879, 2022 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-35771599

RESUMO

The first asymmetric synthesis of microgrewiapine C, a piperidine alkaloid isolated from Microcos paniculata, is reported. This synthesis prompted correction of the 1H and 13C NMR data for the natural sample of the alkaloid, which was achieved by reanalysis of the original spectra. The corrected data for the natural product were found to be identical to those of the synthetic sample prepared herein, thus confirming the structural and relative configurational assignment of microgrewiapine C. Although comparison of specific rotation values indicates that the (1R,2S,3S,6S) absolute configuration should be assigned to the alkaloid, consideration of potential common biosynthetic origins of microgrewiapine C and congeners suggests that further phytochemical investigations are warranted.


Assuntos
Alcaloides , Malvaceae , Alcaloides/química , Malvaceae/química , Estrutura Molecular , Piperidinas/química , Estereoisomerismo
4.
J Nat Prod ; 85(1): 306-312, 2022 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-34918520

RESUMO

The formation of O-acetyl microgrewiapine A is investigated. NMR data for the authentic sample derived from the natural product are corrected. Wholly synthetic samples, produced from reductive N-methylation of synthetic microcosamine A (to give synthetic microgrewiapine A) followed by O-acetylation, exhibit NMR data that are identical to those of the authentic sample. The previous report that this two-step transformation proceeds with epimerization at C-6 is thus shown to be in error: the purported sample of O-acetyl 6-epi-microgrewiapine A is structurally misassigned and is, in fact, O-acetyl microgrewiapine A. A plausible rationale for the structural misassignment is advanced.


Assuntos
Alcaloides/química , Piperidinas/química , Acetilação , Alcaloides/síntese química , Produtos Biológicos/química , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Metilação , Estrutura Molecular , Piperidinas/síntese química , Espectroscopia de Prótons por Ressonância Magnética
5.
Zhonghua Nei Ke Za Zhi ; 60(10): 898-903, 2021 Oct 01.
Artigo em Chinês | MEDLINE | ID: mdl-34551479

RESUMO

Objective: To explore the correlation between different types of microcirculation alterations and the prognosis in patients with septic shock. Methods: This research employed a prospective observational study methodology for selecting subjects with septic shock. Side-stream dark field(SDF) was used to monitor the sublingual microcirculation to determine the total vascular density (TVD), perfused vessel density (PVD), the proportion of perfused vessels (PPV), and the microvascular flow index (MFI), heterogeneity index (HI) indicators. At the bedside, patients with microcirculation disorders were divided into four types: stasis, dilution, heterogeneity, and hyperdynamic. The 30-day survival status after enrollment and hemodynamics parameters were recorded. Results: A total of 64 patients with septic shock were selected in the study, including 18 cases of stasis type, 11 of dilution type, 18 of heterogeneous type, and 17 of hyperdynamic type. There were statistical differences in the mean arterial pressure (MAP) [stasis:(77±9) mmHg (1 mmHg=0.133 kPa), dilution:(80±11) mmHg, heterogeneity: (78±12) mmHg, hyperdynamic:(88±12) mmHg], TVD [ stasis:(10.84±3.01) mm/mm2, dilution:(9.64±1.72) mm/mm2, heterogeneity:(11.39±2.18) mm/mm2, hyperdynamic: (11.87±2.67) mm/mm2 ], PVD [stasis:(5.93±1.94) mm/mm2, dilution:(6.86±1.48) mm/mm2, heterogeneity: (8.31±1.78) mm/mm2, hyperdynamic:(9.68±2.46) mm/mm2], PPV [stasis:52.45 (46.25, 63.33)%, dilution:73.70 (61.50, 75.20)%, heterogeneity: 71.25 (67.95, 77.00)%, hyperdynamic:80.70 (77.25, 86.45)%], MFI(stasis:1.34±0.45, dilution: 1.70±0.38, heterogeneity:1.82±0.28, hyperdynamic:2.25±0.33), and HI [stasis:0.68 (0.51, 1.87), dilution: 0.57 (0.49, 0.64), heterogeneity:0.70 (0.59, 0.91), hyperdynamic: 0.40 (0.37, 0.52)] of the four types of microcirculation alterations. The cumulative survival rates in stasis, dilution, heterogeneity and hyperdynamic types at 30 day were 7/18, 4/11, 10/18 and 14/17, respectively, which in stasis and dilution types was significantly lower than that of hyperdynamic type (χ²=7.221, P=0.007;χ2=6.764, P=0.009). Multivariate Cox regression analysis showed the type of microcirculation alterations (stasis:RR=4.551, 95%CI 1.228-16.864, P=0.023; dilution:RR=4.086, 95%CI 1.011-16.503, P=0.048), acute physiology and chronic health evaluation Ⅱ (RR=1.077, 95%CI 1.006-1.153, P=0.032) were independent prognostic risk factors. Conclusions: Microcirculation alterations are common in patients with septic shock, and it is hard to predict the types of microcirculation alterations with hemodynamics parameters. The prognosis of patients with septic shock is related to the types of microcirculation alterations, suggesting that routine monitoring of microcirculation might be helpful to guide hemodynamic therapy.


Assuntos
Choque Séptico , Hemodinâmica , Humanos , Microcirculação , Prognóstico , Estudos Prospectivos
6.
Tob Prev Cessat ; 7: 57, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34395954

RESUMO

Smoking is a health hazard. Current smoking cessation measures such as behavioral change counselling by trained professionals, nicotine replacement therapy and medications have limited success. Smoking intensity is assessed using a portable device to measure the smokers' exhaled breath carbon monoxide (eCO) level. A systematic review suggests the potential of serious gaming to increase smoking quit rate. However, the related studies were unable to explain and determine the effect gamification on smoking cessation. A handy personalized eCO measurement device linked to a smart-phone applications (app) has been developed (integrated STEADES-2 system). This novel system incorporates app-based video and print learning resources, authentication function and gamification using the eCO data as game element. Trained multidisciplinary healthcare professionals access the STEADES-2 data to monitor smoking status and support smokers via asynchronous virtual coaching. The pilot randomized controlled trial will enroll 20 smokers to use the STEADES-2 system (intervention group) and another 20 to the existing smoking cessation programme (control group) in primary care. The primary feasibility outcomes will include the recruitment response rate, the smokers' usability of the STEADES-2 system, their self eCO monitoring, frequencies of participation in the serious games and interactions with their virtual coaches. Their smoking literacy, utility and experience of the STEADES-2 system are other outcomes. Smokers in both groups will be compared on their cigarette abstinence as secondary outcome based on eCO levels and urine cotinine test (primary outcomes after 12 weeks). The results will be disseminated via conferences and publications.

7.
Org Biomol Chem ; 19(13): 2847-2855, 2021 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-33720232

RESUMO

Enantiorecognition between a racemic reagent and a racemic substrate can be a valuable process in organic synthesis. This review highlights representative examples of this phenomenon and the use of mutual kinetic resolution as a method for screening of kinetic and/or parallel kinetic resolutions.


Assuntos
Indicadores e Reagentes/química , Compostos Orgânicos/síntese química , Cinética , Estrutura Molecular , Compostos Orgânicos/química , Estereoisomerismo
8.
Zhonghua Nei Ke Za Zhi ; 59(9): 695-699, 2020 Sep 01.
Artigo em Chinês | MEDLINE | ID: mdl-32838500

RESUMO

Objectives: To study the feasibility of using ultrasound to evaluate diaphragm function in patients with invasive mechanical ventilation. Methods: From March to December 2017, 40 adult patients with acute respiratory distress syndrome who were admitted to the Department of Critical Care Medicine, Xiangya Hospital, Central South University for more than 48 hours were included. Diaphragmatic excursion and thickness of bilateral anterior, middle and posterior parts were measured by ultrasound for 5 consecutive days. Results: (1) Compared with the diaphragmatic excursion of the right [anterior: (11.05±3.04) mm; middle: (12.08±2.71) mm; posterior: (11.51±3.33) mm] and left [anterior: (13.63±7.52) mm; middle: (15.44±7.52) mm; posterior: (14.76±6.93) mm] sides on day 1, the diaphragmatic excursion of the right [anterior: (8.90±3.65) mm; middle: (10.02±4.24) mm; posterior: (10.25±4.38) mm] and left [anterior: (9.82±1.96) mm; middle: (11.60±1.13) mm; posterior: (11.52±1.98) mm] sides decreased significantly on day 3 (P<0.05). Bilateral anterior, middle and posterior diaphragmatic excursion recovered on day 5, and was higher than the baseline levels on day 1, with the left middle and posterior diaphragmatic excursion changing most significantly. (2) Compared with day 1, 2, 3, the thickening fraction of bilateral anterior, middle and posterior diaphragm were significantly decreased on day 4, with the left middle part [day 1: (33.87±14.34)%; day 2: (37.26±13.91)%; day 3: (30.56±14.27)%; day 4: (15.53±5.68)%] and the left posterior part [day 1: (35.50±15.69)%; day 2: (39.84±15.32)%; day 3: (29.06±14.96)%; day 4: (13.30±5.79)%] changing most significantly (P<0.05). The thickening fractions of left anterior, middle and posterior diaphragm recovered on day 5 compared with that on day 4, but still lower than those on day 1 (P<0.05). Conclusions: It is feasible to evaluate the diaphragm function in patients with invasive mechanical ventilation by ultrasound, which can provide guidance for preventing diaphragmatic atrophy and withdrawing from mechanical ventilation.


Assuntos
Diafragma , Respiração Artificial , Cuidados Críticos , Humanos , Estudos Prospectivos , Ultrassonografia
9.
Tetrahedron ; 76(2): 130819, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32713969

RESUMO

Following on from ezutromid, the first-in-class benzoxazole utrophin modulator that progressed to Phase 2 clinical trials for the treatment of Duchenne muscular dystrophy, a new chemotype was designed to optimise its physicochemical and ADME profile. Herein we report the synthesis of SMT022357, a second generation utrophin modulator preclinical candidate, and an asymmetric synthesis of its constituent enantiomers. The pharmacological properties of both enantiomers were evaluated in vitro and in vivo. No significant difference in the activity or efficacy was observed between the two enantiomers; activity was found to be comparable to the racemic mixture.

10.
J Med Chem ; 63(5): 2547-2556, 2020 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-31599580

RESUMO

5-(Ethylsulfonyl)-2-(naphthalen-2-yl)benzo[d]oxazole (ezutromid, 1) is a first-in-class utrophin modulator that has been evaluated in a phase 2 clinical study for the treatment of Duchenne muscular dystrophy (DMD). Ezutromid was found to undergo hepatic oxidation of its 2-naphthyl substituent to produce two regioisomeric 1,2-dihydronaphthalene-1,2-diols, DHD1 and DHD3, as the major metabolites after oral administration in humans and rodents. In many patients, plasma levels of the DHD metabolites were found to exceed those of ezutromid. Herein, we describe the structural elucidation of the main metabolites of ezutromid, the regio- and relative stereochemical assignments of DHD1 and DHD3, their de novo chemical synthesis, and their production in systems in vitro. We further elucidate the likely metabolic pathway and CYP isoforms responsible for DHD1 and DHD3 production and characterize their physicochemical, ADME, and pharmacological properties and their preliminary toxicological profiles.


Assuntos
Benzoxazóis/metabolismo , Distrofia Muscular de Duchenne/tratamento farmacológico , Naftalenos/metabolismo , Naftóis/metabolismo , Utrofina/metabolismo , Animais , Hidrocarboneto de Aril Hidroxilases/metabolismo , Benzoxazóis/efeitos adversos , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Redes e Vias Metabólicas , Metaboloma , Camundongos , Distrofia Muscular de Duchenne/metabolismo , Naftalenos/efeitos adversos , Naftóis/efeitos adversos , Naftóis/análise , Naftóis/síntese química , Ratos , Estereoisomerismo
11.
Zhonghua Nei Ke Za Zhi ; 58(11): 814-818, 2019 Nov 01.
Artigo em Chinês | MEDLINE | ID: mdl-31665856

RESUMO

Objective: To investigate the clinical significance of transcranial Doppler (TCD) in early diagnosis of sepsis-associated encephalopathy(SAE). Methods: Septic patients admitted to the intensive care unit(ICU) were recruited at Xiangya Hospital, Central South University from July 2015 to March 2016. Clinical data and TCD parameters during 24 hours after admission were collected. All patients were screened for delirium using the confusion assessment method for the intensive care unit (CAM-ICU) twice a day. The gold standard of the diagnosis of SAE was positive CAM-ICU evaluation. Patients were divided into SAE group and the non-SAE group. TCD data including systolic velocity (Vs), diastolic velocity (Vd), mean velocity (Vm), pulsatility index (PI) and resistant index (RI) were analyzed to determine the optimal diagnostic cut-off value. Results: A total of 43 patients were enrolled including 12 in SAE group and 31 in non-SAE group. Vm and Vd were lower in SAE group [Vm: (53.50±12.22) cm/s vs. (61.68±9.63) cm/s, P<0.05; Vd: (33.42±10.87) cm/s vs. (43.16±7.84) cm/s, P<0.01] but PI and RI were significant higher in SAE group[PI:(1.16±0.2) vs. (0.90±0.15), P<0.01;RI:(0.65±0.08) vs. (0.56±0.06), P<0.01] than in non-SAE group. The cut-off values of Vs, Vm, Vd, PI and RI for the diagnosis of SAE were 112cm/s, 55.50cm/s, 34.50cm/s, 1.16, 0.65, respectively, with the relevant sensitivities of 19.4%, 83.9%, 93.5%, 58.3%, 58.3% and the specificities of 100.0%, 50.0%, 58.3%, 96.8%, 96.8%, respectively. The diagnostic AUC of Vd, PI and RI were 0.741, 0.808 and 0.808 respectively. Conclusions: The parameter changes of TCD suggest that the pathogenesis of SAE is related to cerebral hypoperfusion, TCD is a helpful method for the early diagnosis of SAE.


Assuntos
Circulação Cerebrovascular , Artéria Cerebral Média/diagnóstico por imagem , Encefalopatia Associada a Sepse/diagnóstico por imagem , Ultrassonografia Doppler Transcraniana/métodos , Velocidade do Fluxo Sanguíneo , Estudos de Casos e Controles , Diagnóstico Precoce , Humanos , Unidades de Terapia Intensiva
12.
J Nat Prod ; 82(9): 2659-2663, 2019 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-31486642

RESUMO

The reported characterization data for the allocolchicinoid alkaloid suhailamine, isolated from Colchicum decaisnei and known to have an erroneous structure, have been reanalyzed. This analysis has led to the current proposal that suhailamine has the same structure as N-acetylcolchinol methyl ether (NCME), an assertion that is supported by comparison with previously reported data for NCME. Suhailamine is therefore a phantom natural product, while NCME represents a naturally occurring allocolchicinoid rather than a purely synthetic entity.


Assuntos
Produtos Biológicos/química , Colchicina/análogos & derivados , Éteres Metílicos/química , Colchicina/química , Estrutura Molecular
13.
Org Lett ; 21(19): 7933-7937, 2019 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-31518146

RESUMO

A method to enable the synthesis of conduramines and their N-substituted derivatives (enantiopure or racemic form) in six steps (five steps for N-substituted derivatives) from cyclohexa-1,4-diene is reported. Key features of this reaction sequence include a preparation of benzene oxide that is amenable to multigram scale, and its efficient ring-opening upon treatment with a primary amine. Epoxidation of the resultant amino alcohols (40% aq HBF4 then m-CPBA) is accompanied by hydrolytic ring-opening in situ to give the corresponding N-substituted conduramine derivatives directly. These may undergo subsequent N-deprotection to give the parent conduramines, as demonstrated by the preparation of enantiopure (-)-conduramine A1, (-)-conduramine A2, and (-)-conduramine E2 (the latter two for the first time). The selectivity of the epoxidation reaction is proposed to be the result of competitive ammonium-directed and hydroxyl-directed epoxidation processes, followed by either direct (SN2-type) or conjugate (SN2'-type) ring-openings of the intermediate epoxides.

14.
Zhonghua Nei Ke Za Zhi ; 58(7): 514-519, 2019 Jul 01.
Artigo em Chinês | MEDLINE | ID: mdl-31269568

RESUMO

Objective: To evaluate the role of combining relative alpha variability and electroencephalogram (EEG) reactivity to predict the prognosis of hypoxic-ischemic encephalopathy(HIE) in adult patients. Methods: A total of 28 adult patients with HIE admitted to general intensive care unit at Xiangya Hospital in Central South University were enrolled in this observational study from January2016 to April 2017. These patients with body temperature over 35℃ after 72-hour admission could be continuously monitored at least 12 hours byEEG.At the same time,each patient was assessed for EEG reactivity.Then we analyzed the correlation between EEG reactivity, relative alpha variability and clinical prognosis. Results: EEG reactivity was elicited in 15/28 patients, among whom 12 patients had a good outcome. While in the other 13 patients, EEG reactivity was not elicited, among whom only 3 patients had a good outcome. As to the results ofrelative alpha variability,11/13 patients with degree 3-4were of good prognosis; while only 3/15 patients with degree 1-2 were of good prognosis. Glasgow coma scale(GCS), EEG reactivity, and relative alpha variability were correlated with clinical outcome(χ(2)=5.073,9.073,-3.626, respectively,all P<0.05). The sensitivity of GCS, EEG reactivity, and relative alpha variability to predict the poor prognosis were 69.2%, 76.9%, 84.6%, respectively. The specificity were 73.3%, 80.0%, 73.3%, respectively. The consistency rates were 71.4%, 78.6%, 78.6%, respectively. The positive predictive values were 69.2%, 76.9%, 73.3%, respectively. The negative predictive values were 73.3%, 80.0%, 84.6%, respectively. More importantly, the accuracy of the relative alpha variability combined with EEG reactivity for the prediction of poor prognosis was much higher with the positive predictive value of 90.0%,the specificity of 93.3%, the sensitivity of 69.2%, the consistency rate of 82.1%,and the negative predictive values of 77.8%. Conclusions: The combination of relative alpha variability and EEG reactivityis reliable to predict clinical outcome of patients with HIE.


Assuntos
Eletroencefalografia , Hipóxia-Isquemia Encefálica/diagnóstico , Adulto , Escala de Coma de Glasgow , Humanos , Valor Preditivo dos Testes , Prognóstico , Sensibilidade e Especificidade
15.
Molecules ; 24(7)2019 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-30965582

RESUMO

Sialic acids are a family of acidic monosaccharides often found on the termini of cell surface proteins or lipid glycoconjugates of higher animals. Herein we describe the enzymatic synthesis of the two isotopically labeled sialic acid derivatives d3-X-Gal-α-2,3-Neu5Ac and d3-X-Gal-α-2,3-Neu5Gc. Using deuterium oxide as the reaction solvent, deuterium atoms could be successfully introduced during the enzymatic epimerization and aldol addition reactions when the sialosides were generated. NMR and mass spectrometric analyses confirmed that the resulting sialosides were indeed tri-deuterated. These compounds may be of interest as internal standards in liquid chromatography/mass spectrometric assays for biochemical or clinical studies of sialic acids. This was further exemplified by the use of this tri-deuterated sialosides as internal standards for the quantification of sialic acids in meat and egg samples.


Assuntos
Óxido de Deutério/química , Enzimas/metabolismo , Ácidos Siálicos/biossíntese , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Oxo-Ácido-Liases/metabolismo , Racemases e Epimerases/metabolismo , Ácidos Siálicos/química
16.
Org Biomol Chem ; 17(6): 1322-1335, 2019 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-30633283

RESUMO

The SuperQuat (4-substituted 5,5-dimethyloxazolidine-2-one) family of chiral auxiliaries was first developed by us in the 1990s to address the shortcomings of the Evans (4-substituted oxazolidin-2-one) family of chiral auxiliaries. The incorporation of geminal dimethyl substitution at C(5) has two effects: (i) it induces a conformational bias on an adjacent, otherwise conformationally labile C(4)-substituent so that it projects towards the N-acyl fragment, thus offering superior diastereofacial selectivity in a range of transformations; and (ii) it hinders nucleophilic attack at the endocyclic carbonyl group, facilitating recovery and recyclability of the auxiliary, with enhanced cleavage properties. This review summarises the development and some of the most common uses of the SuperQuat family of chiral auxiliaries, particularly in the synthesis of natural products or other targets having bioloigcal interest. Where possible, comparisons with the performances of the corresponding Evans auxiliaries are presented.

17.
J Nat Prod ; 81(12): 2731-2742, 2018 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-30457859

RESUMO

The asymmetric syntheses of all members of the Hancock alkaloid family based upon a 2-substituted N-methyl-1,2,3,4-tetrahydroquinoline core are delineated. The conjugate addition of enantiopure lithium N-benzyl- N-(α-methyl- p-methoxybenzyl)amide to 5-( o-bromophenyl)- N-methoxy- N-methylpent-2-enamide is used to generate the requisite C-2 stereogenic center of the targets, while an intramolecular Buchwald-Hartwig coupling is used to form the 1,2,3,4-tetrahydroquinoline ring. Late-stage diversification completes construction of the C-2 side chains. Thus, (-)-cuspareine, (-)-galipinine, (-)-galipeine, and (-)-angustureine were prepared in overall yields of 30%, 28%, 15%, and 39%, respectively, in nine steps from commercially available 3-( o-bromophenyl)propanoic acid in all cases. Unambiguously corrected 1H and 13C NMR data for the originally isolated samples of (-)-cuspareine, (-)-galipinine, and (-)-angustureine are also reported, representing a valuable reference resource for these popular synthetic targets.


Assuntos
Alcaloides/síntese química , Quinolinas/síntese química , Alcaloides/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Quinolinas/química
18.
J Org Chem ; 83(17): 9939-9957, 2018 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-30037221

RESUMO

Epoxidations (40% aq HBF4 then m-CPBA) of racemic cis-2-( N-benzylamino)cyclohex-3-en-1-ol and racemic cis-2-( N, N-dibenzylamino)cyclohex-3-en-1-ol proceed with very high levels of diastereoselectivity (>95:5 dr). The latter is in direct contrast to the epoxidation of the corresponding trans-diastereoisomer (which proceeds with essentially no selectivity), showing that the relative configuration of the substrate dramatically influences the diastereoselectivity in these instances. Meanwhile, epoxidations of enantiopure (1 R,2 S,α R)-2-[( N-α-methylbenzyl)amino]cyclohex-3-en-1-ol and (1 S,2 R,α R)-2-[( N-α-methylbenzyl)amino]cyclohex-3-en-1-ol [surrogates for the enantiomers of cis-2-( N-benzylamino)cyclohex-3-en-1-ol] proceed with complete diastereoselectivity (>95:5 dr) under the same conditions, showing that neither the presence of the α-methyl group nor the relative configuration of the α-methylbenzyl stereocenter have an effect upon the established level of diastereoslectivity in these cases. In contrast, epoxidations of enantiopure (1 R,2 S,α R)-2-[ N-benzyl- N-(α-methylbenzyl)amino]cyclohex-3-en-1-ol and (1 S,2 R,α R)-2-[ N-benzyl- N-(α-methylbenzyl)amino]cyclohex-3-en-1-ol [surrogates for the enantiomers of cis-2-( N, N-dibenzylamino)cyclohex-3-en-1-ol] proceed with lower diastereoselectivity (∼70:30 dr). Thus, the presence of the α-methyl group has a detrimental effect on the established level of diastereoselectivity in these cases (although again the relative configuration of the α-methylbenzyl stereocenter is unimportant). The diastereoselective epoxidation pathway is used to enable the asymmetric syntheses of six hitherto unknown, enantiopure dihydroconduramines (+)-C-2, (-)-C-2, (+)-D-2, (+)-E-2, (+)-F-2, and (-)-F-2 (>99% ee in each case).

19.
Org Lett ; 20(13): 4135-4139, 2018 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-29943568

RESUMO

Two synthetic routes have been developed for the asymmetric syntheses of (2 R,3 S)- and (2 S,3 S)-3-hydroxyproline. The key synthetic step in each of these strategies is the conversion of protected α,δ-dihydroxy-ß-amino esters (either 2,3- anti- or 2,3- syn-configured) into ß,δ-dihydroxy-α-amino esters (protected forms thereof), via the intermediacy of the corresponding aziridinium ions. The products of these stereospecific rearrangements were then cyclized and deprotected to afford (2 R,3 S)-3-hydroxyproline and (2 S,3 S)-3-hydroxyproline as single diastereoisomers (>99:1 dr) in >26% overall yield.

20.
Zhonghua Nei Ke Za Zhi ; 57(6): 446-449, 2018 Jun 01.
Artigo em Chinês | MEDLINE | ID: mdl-29925131

RESUMO

To explore the present status of fluid therapy and clinical outcome in critically ill patients in intensive care units (ICU). ICU patients consecutively admitted to our ICU were prospectively enrolled. Patients' demographics, laboratory data, fluid record and clinical outcome were collected. Fluid intake quantity of all patients was at peak on the fifth day which was 2 806 (1 997, 3 582) ml. From the fourth day in ICU, fluid balance started to benegative as -84 (-1 127, 612) ml and gradually increased. Crystalloid solution was the main components. For treatment purposes, medication injections and nutrients were major fluids. Positive correlations were found between total fluid intake quantity, total crystalloid volume, total colloidal volume and hospital stay, ICU stay, duration of intubation (r values as 0.211, 0.686, 0.282, 0.155, 0.506, 0.174, 0.209, 0.072, 0.292, respectively P<0.05). Moreover, positive correlations were also demonstrated between total colloidal volume and total bilirubin, direct bilirubin, alanine transaminase, aspartate transaminase, blood urea nitrogen, serum creatinine (r values as 0.196, 0.242, 0.190, 0.335, 0.284, 0.223, respectively P<0.05).


Assuntos
Cuidados Críticos , Estado Terminal/terapia , Hidratação , Unidades de Terapia Intensiva , Soluções Isotônicas/administração & dosagem , Soluções Cristaloides , Humanos , Tempo de Internação , Pessoa de Meia-Idade , Inquéritos e Questionários
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