REDUCTION OF THE PYRIMIDINE RING - REGIOSELECTIVE AND STEREOSELECTIVE SYNTHESIS OF 1,3-DIAMINE DERIVATIVES

1-Butyl-1,2-dihydropyrimidines 2 and 6,7,8,8a-tetrahydropyrrolo[1,2-a]pyrimidines 3 are reduced with an excess of sodium borohydride in methanol to produce stereoselectively N,N'- and N,N-disubstituted 1,3-diamine derivatives 4 and 6, respectively. Partial reduction of 3 to fully saturated pyrrolo[1,2-a]pyrimidines 7 is accomplished using equimolecular amounts of sodium borohydride.