Stereodivergent C-C Bond Formation on Arene-Chromium Template: Endo-Selective Allylation by Hosomi-Sakurai Reaction

摘要

We have presented a rare example of endo-selectivity in arene-chromium chemistry, as observed in conjugate allylation of 2-arylidene-1-tetralone Cr(CO)_3 complex using the Hosomi-Sakurai reaction. Normal exo-selectivity is observed for a similar function-alization via a Grignard-anionic oxy-Cope sequence. Such stereodivergence adds greater flexibility to the design of stereoselective strategies using arene-chromium complexes. The origin of this unusual stereochemical preference may be traced to an out-of-plane coordination of titanium with the carbonyl oxygen. We are currently exploring this theme in the context of π-facial selectivity in a number of varied structures, especially conformationally flexible acyclic substrates.