10.1021/jo0522963
The research aims to systematically investigate the C-glycosylation reactions of acetals related to mannose and other pyranoses to understand the conformational preferences and reactivity of the mannosyl cation, an intermediate in many mannosylation processes. The study's purpose is to gain insights into the structure and reactivity of the mannosyl cation, which is crucial for the development of pharmaceutical agents and for understanding carbohydrate-derived processes. The research concludes that the high R stereoselectivity observed in C-mannosylation is likely due to the interplay between the mannosyl cation's conformational preferences and the transition state energies during nucleophilic attack, rather than ground-state energies alone. Key chemicals used in the study include various acetal derivatives of mannose and other pyranoses, allyltrimethylsilane as a nucleophile, and Lewis acids such as BF3·OEt2 to facilitate the C-glycosylation reactions. The research was supported by the National Institutes of Health and contributions from industry partners.
10.1016/S0008-6215(00)00127-0
The research investigates the heterocyclization reactions of thiosemicarbazones derived from D-galacto, D-gluco, and D-manno configurations under different acetylating conditions. The purpose was to understand the mechanistic pathway for heterocyclization and evaluate factors like starting material configuration, pH of the reaction medium, and reaction time. The study concluded that heterocyclization could occur under both acidic and basic conditions, but the presence of a C=N bond was necessary for the reaction in basic media. Acidic conditions promoted pyranose ring opening, yielding both thiadiazolines, with one being potentially a kinetic product and the other a thermodynamic product. The isolation of both thiadiazolines depended on the carbohydrate under reaction and the interconversion speed between the kinetic and thermodynamic products. Chemicals used in the process included acetic anhydride, pyridine, D-galactose, D-glucose, D-mannose, and various acetylated pyranose products and thiadiazoline derivatives.
10.1246/cl.1981.457
The research focuses on the synthetic studies toward maytansinoids, specifically the preparation of optically active intermediates (15 and 23) from D-mannose. The purpose of this study was to develop a new synthetic strategy for maytansine, a naturally occurring anti-cancer agent, by utilizing D-mannose as a chiral starting material. The researchers synthesized the intermediates through a series of chemical reactions, with a crucial step involving heteroconjugate addition of methyllithium.
10.1021/ja01646a074
The study explores the isomerization of D-glucose to D-mannose using a resin catalyst in carbon dioxide-free water under nitrogen, yielding D-mannose phenylhydrazone. It also investigates the synthesis of amines derived from 3-phenyl-1-indanone through the Mannich reaction with various amines (dimethylamine, diethylamine, piperidine, and morpholine) and formaldehyde, resulting in low yields and unstable products. Further reductions and hydrogenations of these products led to the formation of indene derivatives and aminoalcohols, but no significant pharmacologic activity was observed. Additionally, the study examines the Mannich reaction of p-nitroacetophenone with different amines and formaldehyde, yielding p-(di)-alkylamino-p-nitropropiophenones, which were further reduced to aminoketones and reacted with phenylhydrazine to form pyrazolines.
