Alkylation process for preparing azetidinone compound and starting compound therefor

A process for preparing an azetidinone alkanoic acid compound of the formula (VI):

• ##STR100## wherein R.sup.1 is a lower alkyl group and R.sup.4 is a protected or unprotected hydroxy-substituted lower alkyl group, which comprises reacting an alkanamide of the formula (I):
• ##STR101## wherein R.sup.1 is the same as defined above, and R.sup.2 and R.sup.3 combine together with the adjacent nitrogen atom to form a heterocyclic group which is a member selected from the group consisting of
• a group of the formula:
• ##STR102## wherein X.sup.1 is an oxygen atom or a sulfur atom, Y.sup.1 is an oxygen atom, a sulfur atom, a methylene group or an imino group substituted by an alkyl group or an aryl group, and R.sup.11, R.sup.12, R.sup.13 and R.sup.14 are the same or different and each a hydrogen atom, a C.sub.1 -C.sub.5 alkyl group, a cyano group, an alkoxycarbonyl group, an aralkyl group, or an aryl group, or R.sup.11 and R.sup.12 combine together to form a C.sub.2 -C.sub.6 alkylene chain, and, simultaneously or independently, R.sup.13 and R.sup.14 combine together to form a C.sub.2 -C.sub.6 alkylene chain, or R.sup.11, R.sup.12, R.sup.13 and R.sup.14 combine together with the adjacent two carbon atoms to form a substituted or unsubstituted aromatic cyclic group,
• a group of the formula:
• ##STR103## wherein X is an oxygen atom or a sulfur atom, Y is an oxygen atom, a sulfur atom, a protected or unprotected imino group or a methylene group, Z.sup.1 and Z.sup.2 are the same or different and each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, an aryl group or an aralkyl group, or both combine at the end thereof to form a substituted or unsubstituted alkylene group having 4 to 7 carbon atoms, and Ring A is a substituted or unsubstituted benzene ring or a substituted or unsubstituted heterocyclic ring having 1 to 4 hetero atoms selected from an oxygen atom, a sulfur atom and a nitrogen atom, and
• a group of the formula:
• ##STR104## wherein X, Y and Ring A are the same as defined above, with a compound of the formula (II):
• ##STR105## wherein L.sup.1 is a leaving group and R.sup.4 is the same as defined above, in the presence of a base without using a Lewis acid to give an azetidinone compound of the formula (III):
• ##STR106## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are the same as defined above, followed by subjecting the compound (III) to hydrolysis.