To establish a route to an organorhodium species necessary for such intramolecular additions, cyclobutanones 1 that bear an alkyne moiety were designed (Scheme 1). 2-(2-But- 1-ynylphenyl) cyclobutanone (1a) was synthesized in three steps starting from commercially available 2-bromobenzaldehyde.[5] As a rhodium catalyst, we initially employed hydroxo- (diolefin) rhodium (i) complexes, which have recently been used successfully in the ...
