Studies on Azaindolizine Compounds. XVI. The Allyl Rearrangement of 7-Allyloxy-5, 6-dimethyls-triazolo [1, 5-a] pyrimidime

The thermal rearrangement of 7-allyloxy-5, 6-dimethyl-s-triazolo [1, 5-a] pyrimidine (III) was carried out and five kinds of rearrangement products ; 3- and 4-allyl-5, 6-dimethyl-s-triazolo [1, 5-a] pyrimidin-7 (3H and 4H) -ones (Ib and Ia), 5- (3-butenyl) -6-methyl-s-triazolo [1, 5-a] pyrimidin-7-ol (IV), and its 3- and 4-allyl derivatives (IVb and IVa) were obtained. Among these products, the out-of-ring Claisen rearrangement product (IV) was obtained in 66% yield. This reaction is the first example of out-of-ring migration of an allyl group to an active methyl group.