Vinyl ketones vinylmagnesium bromid

Reaction of vinyl Grignard reagents with a-halo ketones. Vinylmagnesium bromide or vinyllithium (2 equivalents) reacts with a-halocycloalkanones to give 1,2-divinylcycloalkanols, used in oxy-Cope rearrangements for synthesis of large ring ketones (c/ 7, 302-303 8, 412 414).8 Examples ... 

In a synthesis of (+)-pleuromutilin, only a 1 1 mixture of diastereomeric vinylic alcohols (86% yield) was obtained by addition of vinylmagnesium bromide to the precursor ketone. Equilibration of the easily separated undesired alcohol to a 1 1 mixture was achieved by a twofold sulfoxide - sulfenate rearrangement [C6H5SC1, then (EtO)3P in refluxing methanol] raising the overall yield of the desired diastereomer to 70% after two cycles81. 

DL-Valeric acid, 369 Vanadium oxyacetylacetonate, 456 Vanadyl acetylacetonate, see Vanadium oxyacetylacetonate Vanillin, 217 Veratrole, 116 a-Vetivone, 306 Vilsmeir reaction, 129 Vinylacetic acid, 428 crr-Vinylalanes, 141, 142 mww-Vinylalanes, 141, 142 Vinyl azides, 100 Vinyl halides, 142 Vinylidinebisdimethylamines, 400 Vinyl ketones, 71 Vinyllithium, 456 Vinylmagnesium halides, 91 Vinyl triphenylphosphonium bromide, 456-457... 

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