Enantioselective preparation of 3,4,5-trisubstituted-4,5-dihydroisoxazoles and 4-substituted-5,6-dihydro-4H-[1,2]-oxazines by nitrile oxide cycloaddition to α-silyl allyl alcohols
Regio- and stereoselective 1,3-dipolar cycloaddition of nitrile oxide to opticallyactive α-silyl allyl alcohol provides a useful preparation of 3,4,5-trisubstituted 4,5-dihydroisoxazoles, which are readily converted into chiral 4-substituted 5,6-dihydro-4H-[1,2]-oxazines in 73–100% yields on treatment with TBAF.