Synthesis of N-Alkenylpurines by Rearrangements of the Corresponding N-Allyl Isomers: Scopes and Limitations

N-9 and N-7-alkenylpurines have been synthesized by rearrangement of the corresponding N-allyl derivatives, often in good yields and with high stereoselectivity. Base promoted and transition metal mediated rearrangements have been studied. Simple allylpurines were easily rearranged with catalytic amounts of RuClH(CO)(PPh3)3. The efficiency of base promoted rearrangement was highly dependent on the detailed structure of the starting material, but this reaction often occurred with surprisingly high Z-selectivity.