Allylic alcohols reaction with trichloroacetonitrile

O-Allyl imidate esters undergo [3,3]-sigmatropic rearrangements to /V-allyl amides. Trichloromethyl imidates can be made easily from allylic alcohols by reaction with trichloroacetonitrile. The rearrangement then provides trichloroacetamides of IV-allylamines.260... 

The first step in this reaction is formation of the allyl trichloroacetimide 8 formed from allyl alcohol 3 by reaction with trichloroacetonitrile. The allyl amides 9 are formed by the [3,3]-sigmatropic rearrangement of 8, followed by hydrolysis. The reaction proceeds with good yield for primary and secondary amides however, for products where the amide nitrogen is bound to a tertiary carbon atom the yields are generally low. 

Synthesh of amines by l3,3]sigmatropie rearrangement Trichloroacetimidic esters (2) of allylic alcohols (1) can be prepared in 80-100% yield (crude) by reaction with trichloroacetonitrile catal3rzed by the corresponding sodium or potassium alkoxide (O, ether). Inverse addition is preferred for secondary or tertiary alcohols. These esters undergo Claisen-type rearrangement at 25-140° to give allylic trichloroacetamides (3), in which the rrans-isomcr usually predominates. 

Allyl alcohols readily react with trichloroacetonitrile to give the corresponding trichloroacetimidates 145. Activation of the double bond with electrophilic reagents results in ring closure to yield oxazolines 146. The most commonly employed electrophiles include iodine, iodine monochloride, phenylselenyl chloride, and mercuric trifluoroacetate. Other nitriles including cyanogen bromide and N,N-dimethylcyanamide can also be used. Since oxazolines readily hydrolyze to amides, the net effect of this reaction sequence is to produce p-amino alcohols 147 from an allyl alcohol. This strategy has been employed in numerous total syntheses of natural products. Examples are listed in Table 8.18 (Fig. 8.7 Scheme 8.43). ° ... 

An allylic system that is easy to rearrange is a useful tool in a variety of synthetic methods. Allylic alcohol is readily converted into the corresponding trichloroacetimidate by brief treatment with trichloroacetonitrile in the presence of an appropriate base and usually results in high yields. Simple heating of the imidate of the allylic alcohol system induces the rearrangement reaction [79,80] (O Scheme 14). 

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