摘要
An efficient approach to functionalized 4,6-disubstituted-and 4,6,6-trisubstituted-1,3-oxazinan-2-ones skeleton has been developed through the reaction of semicyclic N,O-acetals 4a and 4b with 1,1-disubstituted ethylenes 5 or 8.As a result of such a[4+2]cycloaddition process,4,6,6-trisubstituted-1,3-oxazinan-2-ones 6aa,6af-6au,7ba,7bf-7bw and 6,6-spiro containing 1,3-oxazinan-2-ones 9ad,9ae,10ba-10bg were obtained in 36%-96%yields and with moderate to excellent diastereoselectivities.In addition,the synthesis of(±)-norallosedamine 12 could be conveniently achieved from the cycloadduct 7bf.
基金
the National Natural Science Foundation of China(No.21772027 to B.-G.Wei and 21702032 to C.-M.Si)for financial support.
