MICHAEL TYPE ADDITION OF ISOBUTYRALDEHYDE TO 1-BUTEN-3-ONE CATALYZED BY TRIBUTYLPHOSPHINE

The reaction of isobutyraldehyde (IBA) with l-buten-3-one (MVK) catalyzed by tributylphosphine (TBP) yielded 2,2-dimethyl-5-oxohexanal [1] in 70% yield. 4,4-Dimethyl-2-cyclo-hexen-1-one [3], 4,4-dimethyl-6-(2-methylpropylidene)-2-cyclohexen-l-one [3] and 3-hy-droxy-4,4-dimethyl-l-cycIohexanone [4] were also formed as by-products. The reaction of dialkylacetaldehydes with MVK yielded 2,2-diaikyl-5-oxohexanal [ 6 ]. The reaction of IBA with other vinyl compounds such as acrylonitrile, l-penten-3-one, methyl acrylate promoted by TBP has also been examined. Trioctylphosphine was also found to be effective as a catalyst for the Michael type addition of IBA to MVK. The results indicate that the Michael type addition involves formation of the phosphonium betaine intermediate. © 1979, The Chemical Society of Japan. All rights reserved.