SYNTHETIC STUDIES ON CARBAPENAM SKELETONS (II)

Syntheses of carbapenam skeletons were achieved from 3-benzyloxypropan al through 1,3-dipolar cycloaddition. 3-Benzyloxypropanal was reacted with N-hydroxyglycine ester to give -(2-benzyloxyethyl)-N-alkoxycarbon yl-methylnitrone (6). 1,3-Dipolar cycloaddition of the nitrone with et hyl crotonate gave 3-(2-benzyloxyethyl)isoxazolidine (7). Compound 7 w as transformed to 4-(2-hydroxyethyl)-2-azetidinone (11). Compound 11 w as converted to 4-(2-iodoethyl)-2-azetidinone (13) or 4-phenylthiacarb onylmethyl-2-azetidinone (16) which was cyclized to give 6-(1-hydroxye thyl)carbapenam-3-carboxylate (14,17).