Alcohols Wittig reaction variants

Among insect pheromones a great number of mono- and polyolefinic compounds are found a lot of them can be obtained by the Wittig reaction. Especially the syntheses of sex attractants of female butterflies and moths, which are mostly mono- and bisunsaturated alcohols, acetates or aldehydes 168), offer a broad field for the application of the Wittig reaction and have stimulated the development of many new stereoselective variants. Thus, the methods of salt-free Wittig reactions (Chapter 2) like the sodium amide method11 31 32, the silazide technique33, potassium in HMPA 34,35 or the use of dipolar aprotic solvents like dimethyl formamide 169>, dimethyl sulfoxide 51,170) or hexamethylphosphoric triamide 51 170) were often used. 

With allylic alcohols, there is the possibility of a [2,3] variant of the Wittig rearrangement that can compete with the [1,2] rearrangement described above (Eq. 22, the indicated electron flow is for the [2,3] rearrangement). The reaction is expected to be a one-step, pericyclic process without a distinct carbanion intermediate. This rearrangement has proven to be useful synthetically because its concerted nature can lead to high stereoselectivity. ... 

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