Recent Advances in the Synthesis of Diarylheptanoids.

In the quest for synthesizing biologically important natural products, medicinal chemists embark on an endless journey. This review focuses on the reports published towards the syntheses of diarylheptanoids, classifying them into linear, tetrahydropyran, diarylether, and biphenyl categories. The synthesis methods for each class from 2013 to 2023 are discussed, providing a comprehensive overview of the advancements in the field. Representative natural product examples are highlighted for each category. The review emphasizes the importance of diarylheptanoids in the realms of chemistry and medicine, showcasing their potential as valuable compounds for medicinal and synthetic chemists.

Time-resolving the UV-initiated photodissociation dynamics of OCS.

We present a time-resolved study of the photodissociation dynamics of OCS after UV-photoexcitation at λ = 237 nm. OCS molecules (X1Σ+) were primarily excited to the 11A'' and the 21A' Renner-Teller components of the 1Σ- and 1Δ states. Dissociation into CO and S fragments was observed through time-delayed strong-field ionisation and imaging of the kinetic energy of the resulting CO+ and S+ fragments by intense 790 nm laser pulses. Surprisingly, fast oscillations with a period of ∼100 fs were observed in the S+ channel of the UV dissociation. Based on wavepacket-dynamics simulations coupled with a simple electrostatic-interaction model, these oscillations do not correspond to the known highly-excited rotational motion of the leaving CO(X1Σ+, J ≫ 0) fragments, which has a timescale of ∼140 fs. Instead, we suggest to assign the observed oscillations to the excitation of vibrational wavepackets in the 23A'' or 21A'' states of the molecule that predissociate to form S(3PJ) photoproducts.

Organocatalytic Enantioselective Mannich Reaction: Direct Access to Chiral ß-Amino Esters.

An asymmetric Mannich reaction has been developed to generate chiral ß-amino esters in good yields with excellent enantiomeric excesses (ee, up to 99%) using a chiral bifunctional thiourea catalyst derived from (R,R)-cyclohexyldiamine. This is the first report on the addition of 3-indolinone-2-carboxylates to N-Boc-benzaldimines generated in situ from α-amidosulfones, which proceeds under mild conditions.

Soft X-ray Absorption Spectroscopy of Aqueous Solutions Using a Table-Top Femtosecond Soft X-ray Source.

We demonstrate the feasibility of soft X-ray absorption spectroscopy in the water window using a table-top laser-based approach with organic molecules and inorganic salts in aqueous solution. A high-order harmonic source delivers femtosecond pulses of short wavelength radiation in the photon energy range from 220 to 450 eV. We report static soft X-ray absorption measurements in transmission on the solvated compounds O=C(NH2)2, CaCl2, and NaNO3 using flatjet technology. We monitor the absorption of the molecular samples between the carbon (∼280 eV) and nitrogen (∼400 eV) K-edges and compare our results with previous measurements performed at the BESSYII facility. We discuss the roles of pulse stability and photon flux in the outcome of our experiments. Our work paves the way toward table-top femtosecond, solution-phase soft X-ray absorption spectroscopy in the water window.

Asymmetric Robinson Annulation of 3-Indolinone-2-carboxylates with Cyclohexenone: Access to Chiral Bridged Tricyclic Hydrocarbazoles.

A chiral bifuntional thiourea catalyzed diastereo- and enantioselective Michael addition followed by an intramolecular Aldol reaction of 3-indolinone-2-carboxylates with cyclohexenone has been accomplished using a chiral thiourea catalyst. It is a novel strategy for the construction of chiral bridged tricyclic hydrocarbazole derivatives bearing four contiguous stereocenters with excellent diastereo- and enantioselectivity.

Oxidative Asymmetric Aza-Friedel-Crafts Alkylation of Indoles with 3-Indolinone-2-carboxylates Catalyzed by a BINOL Phosphoric Acid and Promoted by DDQ.

An asymmetric aza-Friedel-Crafts alkylation reaction between indoles and indolenines that were derived in situ from 3-indolinone-2-carboxylates has been developed by using 3,3'-bis(triphenylsilyl)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate as a catalyst. The reaction proceeded under mild conditions and provided chiral indol-3-yl-3-indolinone-2-carboxylate derivatives in good yields with excellent ee values (up to 98.6 %). Similarly, the Mannich-type addition of indoline-3-ones to indolenines provided heterodimers with vicinal chiral quaternary centers. This method was successfully applied to the construction of the core structure of trigonoliimine C.

Organocatalytic Enantioselective Amination of 2-Substituted Indolin-3-ones: A Strategy for the Synthesis of Chiral α-Hydrazino Esters.

An efficient enantioselective α-amination of 2-substituted 3-indolinones has been achieved for the first time using hydroquinidine as a chiral catalyst through an aza-Michael reaction. The desired α-hydrazino esters are obtained in excellent yields with high enantiomeric excess leading to a quaternary stereocenter with a broad substrate scope.

Cooperative Multicatalytic System for the One-Pot Synthesis of Octahydrospiro-ß-carbolines.

A domino cyclization of 3-((3-(2-aminophenyl)prop-2-ynylamino)methyl)but-3-en-1-ol with aldehydes has been accomplished employing 5 mol % of the Ph3PAuCl/AgSbF6/In(OTf)3 system to afford the corresponding octahydrospiro[pyran-4,4'-pyrido[3,4-b]indole] derivatives in good yields with high selectivity. This is the first report on the synthesis of spiro-ß-carbolines through a multicatalytic cascade process.

Substrate Directed C-H Activation for the Synthesis of Benzo[c]cinnolines through a Sequential C-C and C-N Bond Formation.

A wide range of benzo[c]cinnolines are prepared through a sequential C-C and C-N bond formation by means of an oxidative C-H functionalization. The reaction proceeds via the C-arylation of 1-arylhydrazine-1,2-dicarboxylate with aryl iodide using Pd(OAc)2/AgOAc followed by an oxidative N-arylation in the presence of PhI/oxone in trifluoroacetic acid. It is entirely a new strategy to generate the benzo[c]cinnoline libraries with a diverse substitution pattern.

Energy linkage between the singlet and triplet manifolds in LaH, and observation of new low-energy states.

Wavelength-resolved fluorescence spectra of jet-cooled LaH were obtained from D1, E1, and 0(+)((3)Σ(-)) states by exciting isolated rotational levels. The observation of a(3)Δ(1) and a(3)Δ(2) states at 1259.5(5) and 1646(1) cm(-1), respectively, established the missing energy link between the singlet and triplet manifolds. The low-energy b(3)Π(0,1) and B(1)Δ(2) states predicted earlier from ab initio studies were also observed for the first time. Vibrational constants ω(e) = 1418(2) cm(-1), ω(e)x(e) = 15.6(7) cm(-1) for the ground and ΔG(1∕2) = 1326.1(7) and 1312(1) cm(-1), respectively, for the a(3)Δ(1) and b(3)Π(1) states were also determined. Vibrational frequencies were found to be in excellent agreement with earlier ab initio values. However, ab initio term energies and spin-orbit separation of (3)Δ(2)-(3)Δ(1) and (3)Π(1)-(3)Π(0) were found to be in poor agreement with the present observations. Also, the (3)Π state that was predicted to be inverted is observed to be regular.

Characteristics of patients with chronic hepatitis-B virus infection in an urban hospital.

BACKGROUND: In the United States, among patients with hepatocellular carcinoma (HCC) and portal hypertension from chronic hepatitis-B virus infection, 44% were Hispanic and 28% were African American. Because our institution (Bronx Lebanon Hospital Center, Bronx, NY) predominantly serves these populations, we studied retrospectively the characteristics of patients with chronic hepatitis-B virus infection. METHODS: We reviewed the medical records of all patients aged > 18 years with chronic hepatitis-B virus infection who had been evaluated at our institution between January 1, 2002 and May 31, 2005. RESULTS: We identified 167 patients with chronic hepatitis-B virus infection. Only 12 (7%) patients underwent chronic hepatitis-B virus treatment. One-hundred-forty-six (87%) patients without decompensated liver cirrhosis were not treated owing to the following reasons: normal alanine aminotransferase level (86%), active injection drug or heavy alcohol use (9%), lack of health insurance coverage (3%) and noncompliance with visits during the evaluation period (2%). HCC screening was performed in 78 patients (47%). Lack of insurance coverage and compliance issues were predictors for HCC screening (p = 0.04 and p < 0.001, respectively). CONCLUSIONS: In the South Bronx, 87% patients were not considered candidates for hepatitis-B virus treatment because of normal alanine aminotransferase levels and the interference of potentially modifiable social factors. Only 47% of our patients with chronic hepatitis-B virus infection underwent HCC screening because of lack of insurance coverage and compliance issues.