(2R)-5-methylene-2-{(1R)-2-oxo-1-[(2-thienylacetyl)amino]ethyl}-5,6-dihydro-2H-1,3-thiazine-4-carboxylic acid
(2r)-5-methylene-2-{(1r)-2-oxo-1-[(2-thienylacetyl)amino]ethyl}-5,6-dihydro-2h-1,3-thiazine-4-carboxylic acid