Diastereoselective titanium-mediated construction of cis-2,3-ring annelated 1-(2-chloroethyl)cyclopropanols

Titanium(IV)-mediated cyclopropanation induced by reaction of cycloalkylmagnesium bromides 1a–e in the presence of titanium tetraisopropoxide with ethyl beta-chloropropionate 2 yielded cis-fused 1-(2ʹ-chloroethyl)cyclopropanols 3b–e with diastereoselectivity highly depending on the ring size. Unexpected rearrangement products 5d,e were isolated in some cases.