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Ketones and aldehydes were effectively reduced by the reaction with CaH 2 and R 3 SiCl in the presence of a catalytic amount of ZnCl 2 . In the absence of the carbonyl substrate, the reagent reduced R 3 SiCl to the corresponding hydrosilane under mild reaction conditions. Leave this area blank for abstract info.

Ketones 1 were converted to α-quaternary α-vinyl ketones 2 by reaction with propargyltitanium reagents, derived from propargyl carbonates 3 and a divalent titanium reagent, followed by rearrangement of the resulting α-allenyl alcohols 4 with NBS.Leave this area blank for abstract info.

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Insertion reactions O 0288Two-Step Allylic Carbon Insertion Between Ketone Carbonyl and α Carbons Giving α-Quaternary α-Vinyl Ketones. -A two-step sequence involves a highly regioselective allenylation of ketones followed by rearrangement of the resulting α-allenyl alcohols with NBS. It allows the synthesis of α-quarternary α-vinyl ketones. -(HE, J.-Q.; SHIBATA, D.; OHNO, C.; OKAMOTO*, S.; Tetrahedron Lett. 49 (2008) 47, 6724-6727; Dep. Mater. Life Chem., Kanagawa Univ., Kanagawa, Yokohama 221, Japan; Eng.) -Mais 10-041