Allyl cyanate-to-isocyanate rearrangement for the synthesis of quaternary stereocenter with nitrogen substituent.

The stereochemistry and efficiency of an allyl cyanate-to-isocyanate rearrangement for the construction of quaternary stereocenter with nitrogen substituent was investigated by the synthesis of (R)-alpha-methylphenylalanine. The rearrangement was found to be stereospecific, and the chirality of allyl carbamate was transferred to that of the quaternary carbon bearing isocyanate group. These results establish that an allyl cyanate-to-isocyanate rearrangement is a useful method for the synthesis of natural products, that contain the quaternary carbon with nitrogen substituent.