Synthetic studies on β-lactam antibiotics. 13. Transformation of 6-epipenicillins to 2R-{(1S, 5R)-2-oxa-6-oxo-4,7- diazabicyclo[3.2.0]hept-3-en-7-yl}-3-methylbut-3-enoates
Synthetic studies on β-lactam antibiotics. 13. Transformation of 6-epipenicillins to 2R-{(1S, 5R)-2-oxa-6-oxo-4,7- diazabicyclo[3.2.0]hept-3-en-7-yl}-3-methylbut-3-enoates