Synthesis of perhydrooxazinones from 2-aza-3-trimethylsilyloxy-1,3-butadiene. A general route to 3,3-disubstituted-beta-hydroxy acids

1-Phenyl-2-aza-3-trimethylsilyloxy-1,3-butadiene reacts with aliphatic, aromatic and cyclic ketones to give in good to excellent yields 6,6-disubstituted-1,3-perhydro-oxazin-4-ones which, in turn, have been readily converted into beta -hydroxy carboxylic acids.