Selective reduction of αβ-olefinic amides and lactams by magnesium and methanol

Abstract

αβ-Olefinic amides with various substitution patterns at the carbon–carbon double bond and at nitrogen are all reduced to the corresponding saturated amides by magnesium and methanol. The same reducing system reduces N-benzyl-8-azabicyclo[4.3.0]nona-1(6),3-dien-7-ones at the conjugated double bond to give mixtures of the cis-and trans-dihydro-derivatives; the isolated, non-conjugated double bond is not reduced, even in the 3,4-diphenyl-substituted compound. Magnesium and methanol reduces quinolin-2(1H)-ones to their 3,4-dihydro-derivatives, and 5,6,7,8-tetrahydroquinolin-2(1H)-one to a mixture of two dihydro-derivatives.