Synthesis of (R)-α-benzylmethionine: a novel rearrangement during alkylation of the Seebach (R)-methionine oxazolidinone
Abstract
Alkylation of the enolate of the Seebach (R)-methionine oxazolidinone with benzyl bromide gave the expected benzylated product in low yield. The major product was a novel amine arising from oxazolidinone cleavage, decarboxylation, alkylation and finally hydrolysis. The rearrangement could be suppressed by using a more reactive electrophile or by using the N-Cbz instead of the N-benzoyl protecting group, and the required (R)-α-benzylmethionine was obtained in 78% yield and in an enantiomeric ratio of 90 : 10.