Baozhen Yang

Stereospecific synthesis of oxazolo(3,4- b)tetrahydroisoquinolin- 3-ones, analogs of podophyllotoxin, via benzotriazole methodology

Abstract A stereospecific synthesis of 2-azapodophyllotoxin analogues based on benzotriazole methodology is reported. Intramolecular Friedel–Crafts reactions of benzotriazole Mannich adducts 2/3b–l afforded 5-substituted oxazolo[3,4-b]tetrahydroisoquinolines 5b–l as pure stereoisomers.

A SHORT ASYMMETRIC SYNTHESIS OF 2,5-DISUBSTITUTED PYRROLIDINES

Abstract A novel approach to chiral 2,5-disubstituted pyrrolidines, starting from chiral 2-phenyl-glycinol, 1,5-dimethoxytetrahydrofuran, and benzotriazole, involves the diastereoselective substitution by Grignard reagents of a benzotriazolyl group in a crystalline intermediate obtained in high yield.

EFFICIENT AND FACILE ROUTES TO NITRONES

(2000). EFFICIENT AND FACILE ROUTES TO NITRONES. Organic Preparations and Procedures International: Vol. 32, No. 2, pp. 175-183.

Convenient One-Pot Methodology for the Primary Aminomethylation of Electron Rich Heterocycles

Abstract Primary aminomethyl groups were introduced into the 2-position of electron rich heterocycles in moderate to good yields by a one-pot sequence involving lithiation, transmetalation into an organozinc reagent and treatment with 1-(triphenylphosphoroylideneaminomethyl) benzotriazole (betmip).

Enantioselective synthesis of ethyl 6-substituted-2,3,3a,4,5,6-hexahydro-1H-indolo[3,2,1-de][1,5]naphthyridine-2-carboxylates from tryptophan

Abstract Optically pure ethyl 6-substituted-2,3,3a,4,5,6-hexahydro-1H-indolo[3,2,1-de][1,5]naphthyridine-2-carboxylates (6–9) have been prepared from ethyl 6-benzotriazolyl-2,3,3a,4,5,6-hexahydro-1H-indolo[3,2,1-de][1,5]naphthyridine-2-carboxylate (5), itself obtained from the reaction of the ethyl ester of L-tryptophan with benzotriazole and 2,5-dimethoxytetrahydrofuran.

Diastereoselective Synthesis of N-Substituted Ethyl 4-Phenyloxazolidine-2-carboxylates

(S)-2-Phenylglycinol, ethyl glyoxylate, formaldehyde and benzotriazole formed stereospecifically ethyl (2S,4S)-N-(benzotriazol-1-yl)methyl-4-phenyloxazolidine-2-carboxylate (1) which was converted into chiral N-substituted oxazolidines, via regiospecific substitutions of the benzotriazolyl residue.