Two efficient and practical synthetic methodologies for the construction of small ring systems have been developed. The fist method involves a novel rearrangement of cyclobutanes 10 and 14 leading to cyclopropanes 11 and 15 employing BF3OEt2 or POC13 in the presence of pyridine or Raney nickel. The second method utilizes a novel cascade reaction of a, P- unsaturated esters 25 and 36 possessing a cyclopropyl ketone moiety with TMSI in the ...