Process for the preparation of 1-carbapenems and intermediates via trithioorthoacetates

A compound having the structural formula:

• ##STR281## wherein R.sup.1' is hydrogen or a readily removable trialkylsilyl protecting group;
• R.sup.a, R.sup.b and R.sup.c are independently selected from the group consisting of alkyl having 1-6 carbon atoms, phenyl and phenylalkyl having 7-10 carbon atoms;
• and wherein R.sup.6 and R.sup.7 are independently selected from the group consisting of:
• hydrogen;
• mono substituted and unsubstituted:
• alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms;
• cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties;
• phenyl;
• aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms;
• wherein the substituent or substituents relative to the above-named radicals are selected from the group consisting of:
• chloro, bromo, fluoro, R.sup.1, ##STR282## wherein, relative to the above listed substituents on R.sup.6, and R.sup.7, the group R.sup.1 and R.sup.2 are independently selected from:
• hydrogen, alkyl, alkenyl and alkynyl, having from 1-10 carbon atoms;
• cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties;
• phenyl;
• aralkyl, aralkenyl and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms;
• R.sup.6 and R.sup.7 are not both hydrogen at the same time;
• when R.sup.6 /R.sup.7 is hydrogen, then R.sup.7 /R.sup.6 is not ##STR283##