Abstract
We have been interested in various 5,6-dihydrouracils and 5,6-dihydroorotic acid derivatives as possible inhibitors of dihydrouracil dehydrogenase, dihydroorotase, and dihydroorotate dehydrogenase.2 The known methods for the synthesis of 5,6-dihydrouracils and 5,6-dihydroorotic acid derivatives are either a low yield cyclization process3 or a catalytic hydrogenation4 procedure which frequently led to the elimination of desired functionality5. In order to obviate these difficulties, we have recently developed6 a mild non-catalytic method for the reduction of 5,6-double bond of uracil and orotic acid derivatives. By using lithium tri-sec-butyl borohydride7–8 we have been able to reduce N1, N3-dialkyl uracil and orotic acid derivatives to the corresponding 5,6-dihydrouracil and orotic acid derivatives as shown in scheme (1).