Competing cyclopropane over epoxide formation from γ-halogeno-δ-hydroxy-ketones

Carbocyclization has been selectively achieved over epoxide formation from a γ-chloro-δ-hydroxy-ketone in the presence of a lithiumamide or using a different strategy in which the related silyloxyenol ether bearing an iodine atom at gamma-position and a silyloxy group in delta-position is reacted with tetrabutylammonium fluoride. These approaches take advantage of (i) the poor reactivity of the intermediate β-halogeno lithiumalkoxide first formed in the former case and (ii) the poorer ability of the fluoride ion to desilylate a silyl ether over a silylenol ether.