An asymmetric isoxazole annulation

An Asymmetric isoxazole annulation proceeds from the (S)-O-methoxyphenylalaninol imine of (RS)-2-phen-ylpropionaldehyde (3). Deprotonation, quenching with 4-chloromethyl-3,5-dimethylisoxazole, and hydrolysis produced isoxazolylaldehyde (5), whose structure was confirmed by single crystal X-ray diffractometry. The absolute configuration of (-)-5 was established as (R)-by chemical correlation to the known (S)-(-)-4-methyl-4-phenyl-cyclohex-2-ene-1-one (7).