A Concise Synthesis of (S)-β-Methylisoleucine

Significance

The SeO₂-promoted oxidative rearrangement of 2-substituted oxazolines 2 into 3, followed by hydrogenation-hydrogenolysis, allows convenient access to chiral α-amino acids 4. Oxazinone 3 (R = H) can be viewed as a chiral glycine synthon. The authors reported a highly diastereoselective addition of dimethylallylstannane to the unsubstituted oxazinone (S)-3 under Brønsted acid catalysis. The product 5 can be efficiently converted into the highly branched amino acid l-β-methylisoleucine (6), an amino acid residue found in biologically active marine-derived peptides.