Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... 1-Oxacephem skeletons were constructed in a convergent manner starting from building blocks and , which were easily prepared from penicillin and diketene, respectively, followed by intramolecular carbene insertion reaction of the resulting intermediate . ... 2 OH), 7.03 ( , 1H, Ph 2 ), ...