SYNTHESIS AND STRUCTURE DETERMINATION OF (3S,5S)-2,3,5,6-TETRAHYDRO-3,5-DIALKYL-N-(TERT-BUTYLOXYCARBONYL)-4H-1,4-OXAZINE-2-ONES

(5S)-2,3,5,6-Tetrahydro-5-alkyl-N-(tert-butyloxycarbonyl)-4H-1,4-oxazine-2-ones, which are readily prepared from optically pure 2-amino alcohols alkylate selectively at the C-3 position to give (3S, 5S)-dialkyl-2,3,5,6-tetrahydro-5-alkyl-N-(tert-butyloxycarbonyl)-4H-1,4-oxazine-2-ones in good yield. The structures of compounds 3e, 5c, 5g, 6h, and 5h (p-bromobenzoate) were determined by single crystal X-ray analysis. The structure of 5b was determined by conversion to optically active diols 6 and 7 and the structure of 5f was determined by correlation to 5c.