Hsi Lin Lee

Synthesis of d-biotin from cysteine

Abstract A novel approach to d-biotin from cysteine, which a utilizes the nitrate oxide To enolthioether double bond cyclization for the formation of C2-C3 of the thiophane ring and the incorporation of the 3-N in the biotin molecule, Is described. the cis relation of the n-butyl side chain and the sulfur in respect to isoxazolidine ring in the bicycle diastereomers 9 And 12 is characterized by an NMR signal For The α- methylene protons of the side chain as a multiplelet at δ1.82 AND 1.80, respectively, ownfield from the multiplet at 1.33 AND 1.32, respectively, for the other two methylenes of the side chain.

Total Synthesis of Dihydrocinchonamine

Abstract Cinchonamine (1) is the best known member of a small group of 2,2-indolquinuclidine alkaloids found in the bark of certain Cinchona and Remijia species 1 and in the leaves of Isertia hypoleuca2. Its isolationwas reported in 18813, the ambiguities was elucidated in 19504, and very recently5 th ambiguities concerning the absolute configuration at C-3 were resolved. Synthetic efforts resulted in the partial synthesis of cinchonamine6, dihydrocinchonamine7,8, and its 10-methoxy-analog5,9 from cinchonine, cinchonidine and quinine.