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Synthesis of all stereoisomers and some congeners of isocytoxazone

cis-Isocytoxazone 2a and trans-isocytoxazone 2b, structural isomers of the antiasthmatic agent cytoxazone (-)-1, and their 5-substituted congeners 23-28 have been prepared. Aldol reaction of para-substituted benzaldehydes with 7-chloro-1-methyl-5-phenyl-1, 4-benzodiazepin-2-one, followed by separation of diastereomeric racemates afforded 3-10. Acid-catalyzed 1, 4-benzodiazepine ring opening, and transformation of the methyl esters of beta-aryl-beta-hydroxy-alpha-amino acids (11-16) via 4-methoxycarbonyl derivatives of 1, 3-oxazolidin-2-one (17-22) and their reduction afforded the, target oxazolidin-2-one derivatives 23-28. Racemic isocytoxazones 2a and 2b were prepared by an independent route starting from 4, methoxystyrene epoxide. Pure enantiomers of these diastereomeric racemates were separated by HPLC chromatography on chiral stationary phases. Their CD spectra, along with those of previously prepared enantiomers of cis-cytoxazone la and trans-cytoxazone 1b are discussed.

1; 4-benzodiazepines; Ring opening; Oxazolidin-2-ones; Chiral hplc

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