Synthesis of Alkyl-Substituted 1,3-Diketones via the 1,4-Addition of the Grignard Reagents to α,β-Unsaturated Imidates

Article abstract of DOI:10.1246/bcsj.62.1601

4-Propyl-3,5-nonanedione was selectively formed by the reaction of methyl N-phenylacrylimidate with ethylmagnesium bromide in 80percent yield.Similar diketones were obtained from methyl N-phenylcrotonimidate and N-phenylcinnamimidate with the Grignard reagents.The coupling of N-magnesio α-methoxy enamine and ketenimine, both of which are formed through the initial 1,4-addition of the Grignard reagent to α,β-unsaturated imidate, is the most plausible pathway for the formation of the diketones.