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Please login or sign up for a free trial to access the full content. Method 3: [2,3]-Wittig Rearrangements

DOI: 10.1055/sos-SD-020-00195

Phillips, A. J.; Love, C. E.Science of Synthesis, (200720255.

In a similar vein to α-(alkenyloxy)esters and amides, α-(alkenyloxy)acids 19 undergo [2,3]-Wittig rearrangement upon treatment with 2 equivalents of strong base (typically lithium diisopropylamide) to provide α-hydroxy-γ,δ-unsaturated acids 20 (Scheme 22).[‌64‌‌66‌] The reader is also directed to the section on the [2,3]-Wittig rearrangement of esters (Section Scheme 22 shows typical examples of the [2,3]-Wittig rearrangement of α-(alkenyloxy)acids. The reaction is highly E selective when performed on secondary allylic alcohols [e.g., entries 5 and 6 (22 from 21)], although diastereoselectivity for reactions employing substituted alkenes is modest (e.g., entries 2, 3, and 4).

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