Allylic alcohols pinacol rearrangement

The stereoeontrolled construction of hydroazulenones is achieved by sequential anionic oxy-Cope rearrangement/SN allylic ether displacement of Cope precursors 5 and 7y71. Optically active compounds 5-8 are prepared from (-)-(lR,6S)-A4(10)-caren-rrons-3-ol via intermediates 3 and 4 by individual exposure of 3 and 4 to 3 equivalents of vinylmagnesium bromide. This reagent promotes initial pinacol rearrangement with liberation of a cyclohexanone unit which is captured by a second equivalent of the organometallic. The divinyl alcohol pairs 5/6 and 7/8 are isolated in 2 1 ratios (43-82% combined yields after MPLC). 

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