| Abstract
| - A convergent, large-scale, chiral synthesis of isoxazoline1 has been achieved in 37% overall yieldand >99.6% optical purity, starting from l-asparagine and4-cyanobenzaldehyde. Hofmann reactionofNα-n-Boc-l-asparaginewith iodosobenzene diacetate provides optically pureNα-n-Boc-l-α,β-diaminopropionic acid (8) in 75% yield. A process oflipase resolution−base catalyzed epimerizationgives the single enantiomer 5. Reaction of acid5 with amine 9 in the presence of thionylchlorideforms the framework of 1. A Pinner reaction ofintermediate 4 in methyl acetate or anisole,followedby an amidination with ammonium acetate, gives optically pure product1.
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