p. 7445 - 7448
(2007/10/02)p. 2493 - 2503
(2007/10/02)(E)-2-((1R,5R)-3-Benzyl-7-oxo-4-thia-2,6-diaza-bicyclo[3.2.0]hept-2-en-6-yl)-3-trifluoromethanesulfonyloxy-but-2-enoic acid benzhydryl ester
(E)-2-((1R,5R)-3-Benzyl-7-oxo-4-thia-2,6-diaza-bicyclo[3.2.0]hept-2-en-6-yl)-3-hydroxy-but-2-enoic acid benzhydryl ester
(R)-2-((1R,5R)-3-Benzyl-7-oxo-4-thia-2,6-diaza-bicyclo[3.2.0]hept-2-en-6-yl)-3-methyl-but-3-enoic acid benzhydryl ester
2-<3-benzyl-6-oxo-2-thia-4,7-diaza-(1R,5R)-bicyclo-<3.2.0>-hept-3-en-7-yl>-benzhydryl acetate
2-((1R,5R)-3-Benzyl-7-oxo-4-thia-2,6-diaza-bicyclo[3.2.0]hept-2-en-6-yl)-3-methyl-but-2-enoic acid benzyl ester