Ketones a-allyloxy methyl

These authors found that pyrrolidine was indeed able to catalyze the 2,3-Wittig rearrangement of several a-allyloxy methyl ketones with good yields and moderate to good diastereoselectivities (Scheme 40.35). The fact that the major diastereomer had a 1,2-syn relative configuration was explained by assuming that the rearrangement proceeded via an envelope syn transition state. 

Scheme 40.35 Racemic organocatalytic 2,3-Wittig rearrangement of a-allyloxy methyl ketones.

For a more complex example of this type of rearrangement (anionic Claisen rearrangement of a tricyclic a-allyloxy ketone) see ref 108. 2-Allyloxy-3-methyl-2-cyclohexenones109 111 and nitrogen derivatives thereof112 rearrange in a different way. 

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