Propargyl Chlorides as Sources for Cobalt Stabilized γ-Carbonyl Cations
Journal of Organic Chemistry
Hexacarbonyldicobalt complexes of γ-chloroalkynones and γ-chloroalkynoates (5) weee found to undergo silver-mediated Nicholas condensation reactions with silyl enol ethers or silyl ketene acetals (10) to give 1,6-dicarbonyl complexes 11 in fair to good yields. Substrates 5 with γ-alkyl substitution formed diastereomeric products with enol silanes 10a and 10b. Reactions with propiophenone trimethylsilyl enol ether (10b) gave good levels of syn diastereoselection, whereas reactions with cyclohexanone trimethylsilyl enol ether (10a) weee only slightly diastereoselective, favoring the anti diastereomer. When conducted in acetonitrile, the silver-mediated reaction of 5e gave a radical dimerization product 13, isolated as the syn diastereomer. © 1995, American Chemical Society. All rights reserved.
Vizniowski, C. Stephen; Green, James R.; Breen, Tricia L.; and Dalacu, Andrea V.. (1995). Propargyl Chlorides as Sources for Cobalt Stabilized γ-Carbonyl Cations. Journal of Organic Chemistry, 60 (23), 7496-7502.