ABSTRACT
Dytek ®EP (1,3-diaminopentane) is a DuPont commercial diamine produced by the cyanobutylation of ammonia with cw-2-penetenenitrile followed by batch hydrogenation of the aminonitrile, 3-aminopentanenitrile, with Raney® Ni or Co catalysts. During the reduction step, we observed the formation of 2-methyland 2-ethyl-4-ethylhexahydropyrimidines as co-products. These hexahydropyrimidines appear to form by catalytic dehydrogenation of 1,3-diaminopentane followed by addition of 1,3-diaminopentane or alkylation of 3-aminopentanenitrile with 1,3-diaminopentane and subsequent thermal rearrangement of the intermediate enamine to primary imines that are then converted to the hexahydropyrimidines. The postulation of a third route where acetonitrile and propionitrile are intermediates, led to a new synthetic route to 2-alkylhexahydropyrimidines by reduction of nitriles in the presence of a 1,3-diamine. Use of an aminoalcohol, 3-amino-l-propanol with acetonitrile provided a new route to 2-methyl-tetrahydroxazine.
