Dihydrooxazine hydrochloride

Readily available a-chloro nitroso compounds have been used on a number of occasions as hetero-dienophiles since the first report appeared in 1947. The initial adduct of this reaction is unstable and if alcohol solvent is used a dihydrooxazine hydrochloride (89) is produced (equation 33). The cycloadditions proceed under very mild conditions with most 1,3-dienes and, as outlined in Scheme 13, Ae regio-selectivity is excellent. - ... 

---