The 2-acylation of 2-substituted 4-butanolides 2 is moderately sensitive to steric crowding, whereas the subsequent ringopening of 2-acyl-2-alkyl-4-butanolides 4, 11 to give y-chloro ketones 6, 12 by chloride-transferring acid derivatives becomes difficult with bigger lactone substituents. Similar observations pertain to the preparation of y-chlorobutanoyl chlorides 10 from 2-alkyl-4-butanolides 2. The proper choice of the starting 4-butanolides (2a, b or 14 ...