Kozo Sawada

Stereo- and regiospecific allylation of 4-chloroazetidinones with allylsilanes: Convergent synthesis of a key intermediate for (+)-thienamycin

Abstract An efficient stereospecific synthesis of optically active 4-allylazetidinones ( 6 , 7 , 11 , and 15a,b ) has been accomplished using silver-promoted coupling reaction of allylsilanes 5 and 14b with 4-chloroazetidinones ( 3 , 4 , and 10a,b ) derived from penicillins.

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.

Synthetic studies on carbapenem antibiotics from penicillins. II: Regio- and stereoselective aldol reaction of a chiral azetidinone: a synthesis of optically active 6-epicarpetimycins

Abstract Aldol and alkylation reactions of the chiral 4-allylazetidinone 1 gave 3,4-trans-azetidinones as major products, in which 10 was converted in several steps to the optically active 6-epicarpetimycins 2.

An efficient synthesis of 6-oxopenicillanic and 7-oxocephalosporanic acid derivatives

Trifluoromethanesulphonation of benzyl 6-aminopenicillanate (3) and the 7-aminocephalosporanates (7a–c) with (CF3SO2)2O gave the bis(trifluoromethylsulphonate) derivatives (5) and (8a–c), which were then converted into the imines (6) and (9a–c) by treatment with 1,5-diazabicyclo[5.4.0] undec-5-ene or triethylamine, and subsequently hydrolysed with dilute HCl to give the 6-oxopenicillanic acids (1) and 7-oxocephalosporanic acids (2), respectively.

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.