Highly Stereoselective Synthesis of Chiral Alkylallenes by Organocopper(I)-Induced Anti 1,3-Substitution of Chiral Propynyl Esters

Article abstract of DOI:10.1021/jo00276a040

The synthesis of chiral 1,3-dialkylallenes R¹CH=C=CHR² of high enantiomeric purity, by applying homogeneous reaction between organocopper(I) reagents of type <2CuX>MgX-LiX> and chiral propynyl methanesulfonates or sulfinates at low temperatures in THF, is reported.The reactions are generally fast; typically complete conversion is obtained within a few minutes at -60 deg C.Overall, high anti stereoselectivity is observed.A plausible mechanism is put forward, and comparison is made with the stereochemistry of reactions of comparable substrates with d¹⁰ complexes, e.g. of Pd(0).