Cation-Anion Combination Reactions. 20. Reactions of Nucleophiles with trans-3-Methoxy- and trans-3-(Methylthio)acrylophenones

Article abstract of DOI:10.1021/jo00336a015

The reactions of a number of nucleophiles with trans-3-methoxyacrylophenone (MeOAcr) and with trans-3-(methylthio)acrylophenone (MeSAcr) in water and methanol have been studied.The reactions of amines produce enamines as the first observable products, and primary amines show simple kinetics: first-order with respect to amine and first-order with respect to the acrylophenone.Piperidine reactions show kinetics which are consistent with a change in the rate-determining step with a change in amine concentration.Methoxylamine reactions produce the monooximes, and semicarbazide reactions produce the monosemicarbazone with MeOAcr but the disemicarbazone with MeSAcr.The reactions of hydroxide ion produced the enolate of benzoylacetaldehyde, which, at the high base concentration used in the MeSAcr reaction, was further converted to acetophenone and formate ion.Methoxide and cyanide ion reactions given addition across the double bond.Rate constants for the reactions of MeOAcr are 20-1000 times greater than those for corresponding reactions of MeSAcr.There is a very good correlation of the rate constants for reactions of nucleophiles with MeOAcr and those with 2,4-dinitrophenyl acetate in both water and methanol solution.