Carbanion-Accelerated Claisen Rearrangements. 4. Asymmetric Induction via 1,3,2-Oxazaphosphorinanes

Article abstract of DOI:10.1021/jo00235a019

The anions derived from allyl vinyl ethers 1 and 2 undergo rapid and highly selective Claisen rearrangements.The degree of asymmetric induction has been found to be uniformly high (ca.90:10) for various substituent patterns but depends markedly on the presence of lithium cations.The absolute sense of asymmetric induction has been established using chiral, nonracemic 1,3,2-oxazaphosphorinane 2.Two proposals for the transition structures of the phosphorus-stabilized anions are discussed.