Reaction of 3,7-dimethyl-6-methylthio-2-oxopurine (1) with Grignard reagents or organolithiums afforded 8-adducts 2, whereas the corresponding reaction of 3,7-dimethyl-2-oxopurine (6) gave 6-adducts 7. The adducts 2 and 7 were converted into 8-substituted theobromines 4 and 6-substituted 3,7-dimethyl-2-oxopurines 8, respectively. 8-Chlorotheobromine (5) reacted with Grignard reagents in the presence of a catalytic amount of NiBr2,(PPh3)2 to give 4 in good yields.
3,7-二甲基-6-甲
硫基-2-氧
嘌呤(1)与
格氏试剂或
有机锂的反应生成了8-加成物2,而3,7-二甲基-2-氧
嘌呤(6)的相应反应则生成了6-加成物7。加成物2和7分别被转化为8-取代的
可可碱4和6-取代的3,7-二甲基-2-氧
嘌呤8。8-
氯可可碱(5)在催化量NiBr2·(PPh3)2存在下与
格氏试剂反应,良好产率地生成了4。