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1.
J Am Chem Soc ; 146(20): 13741-13747, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38717594

RESUMO

Organic diazo compounds are versatile reagents in chemical synthesis and would benefit from improved synthetic accessibility, especially for larger scale applications. Here, we report a mild method for the synthesis of diazo compounds from hydrazones using a heterogeneous Fe-N-C catalyst, which has Fe ions dispersed within a graphitic nitrogen-doped carbon support. The reactions proceed readily at room temperature using O2 (1 atm) as the oxidant. Aryl diazoesters, ketones, and amides are accessible, in addition to less stable diaryl diazo compounds. Initial-rate data show that the Fe-N-C catalyst achieves faster rates than a heterogeneous Pt/C catalyst. The oxidative dehydrogenation of hydrazones may be performed in tandem with Rh-catalyzed enantioselective C-H insertion and cyclopropanation of alkenes, without requiring isolation of the diazo intermediate. This sequence is showcased by using a flow reactor for continuous synthesis of diazo compounds.

2.
Org Lett ; 25(22): 4000-4004, 2023 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-37249358

RESUMO

Rhodium-catalyzed C-H functionalization of cyclohexadiene derivatives with diaryldiazomethanes followed by oxidation with DDQ provides ready access to triarylmethanes. Two chiral dirhodium tetracarboxylates, Rh2(S-PTAD)4 and Rh2(S-TPPTTL)4, were found to be the optimum chiral catalysts for these transformations. This method showcases the ability of diaryldiazomethanes to perform intermolecular C-H insertion with high enantioselectivity and good yields. The method has a broad substrate scope, leading to triarylmethane products with a variety of aryl and heteroaryl substituents, including benzofuran and pyridine heterocycles.


Assuntos
Ródio , Estereoisomerismo , Oxirredução , Catálise , Ródio/química , Cicloexenos
3.
ACS Catal ; 10(11): 6240-6247, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-37275336

RESUMO

Rhodium-stabilized diaryl carbenes typically generated from diaryldiazomethanes have been generally classified as donor/donor carbenes. This combined computational and experimental study demonstrates that diarylcarbenes display reactivity characteristics that are more reminiscent of donor/acceptor carbenes. When the reactions are carried out with chiral dirhodium catalysts, Rh2(S-PTAD)4 and Rh2(S-NTTL)4, highly enantioselective and diastereoselective cyclopropanations can be achieved, forming 1,1,2-triarylcyclopropanes. The reason for this behavior is because the two rings are unable to align in the plane of the rhodium carbene at the same time. The aryl ring aligned in the plane of the carbene behaves as a donor group, whereas, the aryl ring aligned orthogonally behaves as an acceptor group.

4.
Eur J Med Chem ; 157: 978-993, 2018 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-30165345

RESUMO

Thirty-eight 3-O-substituted-3',4'-dimethoxyflavonols and twenty-five 3-O-substituted-3',4',7-trimethoxyflavonols have been synthesized for systematic investigation on the structure-activity relationships of 3-O-substituted-3',4'-dimethoxyflavonols in three human prostate cancer cell models. Our findings indicate that incorporation of an appropriate amino group to 3-OH of 3',4'-dimethoxyflavonol and 3',4',7-trimethoxyflavonol through a 3- to 5-carbon linker can substantially improve the in vitro antiproliferative potency in three human prostate cancer cell models, but not in two non-neoplastic human epithelial cell models (MCF 10A and PWR-1E). 1-Methylpiperazine, pyrrolidine, and dibutylamine are optimal terminal amine groups that, in combination with a 3- to 5-carbon linker, are notably beneficial to the anti-proliferative potency of 3-O-substituted-3',4'-dimethoxyflavonols. It is worth noting that 3-O-(4-methylpiperazin-1-yl)propyl-3',4',7-trimethoxyflavonol (76) induces PC-3 cell death in a completely different way from 3-O-pyrrolidinopentyl-3',4',7-trimethoxyflavonol (81) even though they belong to 3-O-substituted-3',4',7-trimethoxyflavonols and exhibit similar potency in inhibiting PC-3 cell proliferation, suggesting that the mechanism of action for each specific 3-O-substitutedflavonol varies with different amino moiety. 3-O-(N,N-Dibutylamino)propyl-3',4'-dimethoxyflavonol (42) emerged as the most promising derivative due to its substantially improved potency in cell models, superior bioavailability in rats, and good selectivity of inhibiting prostate cancer cell proliferation over non-neoplastic human epithelial cell proliferation.


Assuntos
Antineoplásicos/farmacologia , Antineoplásicos/farmacocinética , Flavonóis/farmacologia , Flavonóis/farmacocinética , Neoplasias da Próstata/tratamento farmacológico , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Flavonóis/síntese química , Flavonóis/química , Humanos , Masculino , Estrutura Molecular , Neoplasias da Próstata/patologia , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade
5.
Bioorg Med Chem ; 25(17): 4768-4777, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28760528

RESUMO

Twenty-two 3-O-substituted-3',4',5'-trimethoxyflavonols have been designed and synthesized for their anti-proliferative activity towards three human prostate cancer cell lines. Our results indicate that most of them are significantly more potent than the parent 3',4',5'-trimethoxyflavonol in inhibiting the cell proliferation in PC-3 and LNCaP prostate cancer cell models. 3-O-Substituted-3',4',5'-trimethoxyflavonols have generally higher potency towards PC-3 and LNCaP cell lines than the DU145 cell line. Incorporation of an ethyl group to 3-OH of 3',4',5'-trimethoxyflavonol leads to 3-O-ethyl-3',4',5'-trimethoxyflavonol as the optimal derivative with up to 36-fold enhanced potency as compared with the corresponding lead compound 3',4',5'-trimethoxyflavonol, but with reversed PC-3 cell apoptotic response. Introduction of a dipentylaminopropyl group to 3-OH increases not only the antiproliferative potency but also the ability in activating PC-3 cell apoptosis. Our findings imply that modification on 3-OH of trimethoxyflavonol can further enhance its in vitro anti-proliferative potency and PC-3 cell apoptosis induction.


Assuntos
Antineoplásicos/síntese química , Flavonóis/química , Flavonóis/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Flavonóis/síntese química , Humanos , Masculino , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Relação Estrutura-Atividade
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