Organometallics 1988, 7, 563-565
563
Enolates are among the most important synthetic intermediates due to the variety of C-C bond-forming reactions and other functionalizations they mediate. Following the pioneering studies of Stork and Hudrlik2 and House et al.? Li enolates have been the most widely used; however, there has been growing interest in the use of other metals4 in order to obtain improved selectivity. We wish to report the preparation of Ti enolates from ketones and CSHS)~R~~(CO)](CL-?~,~'-HFB).~~ IV) bis(~5-pentamethylcyclopentadienyl)dimethyltitmium( Clearly the M(CO),($-HFB) complexes show great ( 1)5 with regioselectivity comparable to hindered amide promise toward the synthesis of a variety of dimetallabases and the best stereoselectivity yet observed. cyclobutenes. The scope of the reaction, the conversion of the compounds to the corresponding dimetallateAs summarized in Table I, good to excellent yields of trahedranes and their further derivatization as well as the enolates result when the corresponding ketones are heated mechanism13of reactions 1 and 2 are being actively pura t 100 "C with a slight excess of 1 in toluene in a sealed sued in our laboratories. tube (or under a static Ar atmosphere). For example 2methylcyclohexanone (2b)yielded 87% of the less subAcknowledgment. We thank the Natural Sciences and stituted enolate 3b and
