Absolute Stereochemistry of Allylic Alcohols, Amines, and Other Ene Moieties: A Microscale Cross Metathesis/Exciton Chirality Protocol

A microscale chemical/chiroptical protocol for the determination of absolute configurations of allylic alcohols, amines, and related systems has been developed. The method is based on the conversion of the double bonds into a styrene, lambdamax 248 nm (epsilon 15 000), or other styrenoid chromophores by cross olefin metathesis. The obtained styrenoid chromophore then couples with the allylic acylate to yield a distinct couplet. The proposed method allows one to determine the absolute configuration of both moieties flanking the double bond. It also overcomes the restriction of the conventional allylic benzoate method that gives rise to weak CD couplet, for which in many cases only one wing of the couplet is observable.