Deprotection of allylic esters and ethers

A process for the deprotection of an allyl ester of a carbapenem derivative, said carbapenem derivative being characterized by a 2-substituent of the formula ##STR10## in which A represents a C.sub.1 -C.sub.6 straight or branched chain alkylene group;

• R.sup.1 represents an optionally substituted aliuphatic, cycloaliphatic, cycloaliphatic-aliphatic, aryl, araliphatic, heteroaryl, heteroaraliphatic, heterocyclyl or heterocyclyl-aliphatic radical and ##STR11## represents a nitrogen-containing aromatic heterocycle attached to the alkylene group A at a ring carbon atom and quanternized by substituent R.sup.1 which comprises reacting said allyl ester of the carbapenem derivative with from 1.0 to 1.5 molecular proportions of pyrrolidine and a catalytic amount of an organic-soluble palladium complex having a coordinating phosphine ligand in an inert organic solvent at -50.degree. C. to 30.degree. C. during a period of from 10 min. to 4 hrs. to cleave the allyl moiety and recovering the resulting carbapenem derivative.