Highly selective chirally templated isomunchnone cycloadditions of achiral aldehydes: Synthesis of an enantiopure α,β-Dihydroxyacid

Article abstract of DOI:10.1016/S0040-4039(97)00919-2

Additions of p-nitro- and p-methoxybenzaldehyde to isomunchnone derivatives of (5S)-phenyloxazin-3-one and -2,3-dione led to corresponding adducts (3,4,6) with excellent diastereofacial and exo-selectivity. Hydrolysis and subsequent cleavage of adduct 3 permitted recovery of the original template and furnished dihydroxyacid 9 that was transformed into the known ethyl ester 10. Comparison of its optical rotation with the literature value confirmed its high optical purity.