Hideo Hirai

Synthetic studies on carbapenem antibiotics from penicillins. III. Stereoselective radical reduction of a chiral 3-isocyanoazetidinone: a total synthesis of optically active carpetimycins2

A new, efficient synthesis of the optically active carpetimycins 1 from penicillins has been achieved via, as key steps, aldol reaction of isonitrile 19, followed by n-Bu3SnH reduction.

Trithiocyclopropenium ion as a building block for nitrogen heterocycle synthesis

Abstract A new methodology for heterocycle synthesis using trithiocyclo-propenium salt as a building bock is described. Tris( tert -butylthio)cyclopropenium perchlorate ( 1 ) reacts with β-amino acids under basic conditions to give 1,2-dihydropyridines, where cyclopropenium salt serves as the three carbon homologator in heterocyclic ring formation. The selective syntheses of 1,5-benzodiazepines and benzimidazoles from 1 are also described. Reaction of 1 with o-phenylenediamines in dimethylformamide gives 1,5-benzodiazepines as a single product but in methanol benzimidazoles. The selective formation of 1,5-benzodiazepines and benzimidazoles could be accounted for by the solvent participation in the cyclization step.

Synthetic studies on carbapenem antibiotics from penicillins. IV: Stereoselective kinetic protonation of a chiral azetidinone enolate

A stereoselective kinetic protonation of the azetidinone enolate B was studied and an efficient synthesis of2(cis) was achieved via aldol reaction of 5 with acetone followed by the kinetic protonation with Ph3SnH as proton source.