Sodium borohydride mediated reduction of N-Boc protected purines and applications in the synthesis of 7-alkyladenines and tetrahydro[1,4]diazepino-[1,2,3-gh]purines

Electron deficient purines can be reduced to 7,8-dihydropurines when treated with cheap and easy-to-handle sodium borohydride in methanol. The dihydropurine formed by reduction of tris-Boc-protected adenine is a useful intermediate in efficient syntheses of 7-alkyladenines and tetrahydro[1,4]diazepino[1,2,3-gh]purines.