Hydroacylation of Alkenes and Alkynes

Acylmetal hydride is formed by the oxidative addition of aldehyde, and hydroacylation occurs by insertion of alkene or alkyne. The Ni-catalysed hydroacylation of internal alkyne 600 with aldehyde gave rise to the v./l-unsaturated ketone 601 [230]. The Ru-catalysed hydroacylation of cyclohexene with aldehyde 602 under CO pressure at high temperature gives the ketone 603 [231]. 

Facile decarbonylation of aldehydes with the Rh complex (Wilkinson complex) is known [43,44], The reaction is explained by the oxidative addition of aldehyde to Rh, followed by decarbonylation and reductive elimination. However, the Rh-catalysed intramolecular reaction of some unsaturated aldehydes proceeds without the decarbonylation, and cyclic ketones are obtained. Treatment of unsaturated aldehyde 

604 under ethylene atmosphere with a catalytic amount of the Rh complex afforded the cyclohexanone 605 by insertion of the double bond to the acyl Rh—H bond (hydroacylation) [232,233], The allyl vinyl ether 606 undergoes Claisen rearrangement to give 4-enal 607, and cyclopentanone 608 is formed by its intramolecular hydroacylation in the presence of the Ru or Rh catalyst [234], 4-Substituted 4-enals 609, bearing primary and secondary substituents, are converted to the corresponding cyclopentanones 610 with 93 96% ee using [Rh(5,5-Me-Duphos)(acetone)2]PF6 [235], 

The Rh-catalyzed hydroacylation of alkynes is also possible. Reaction of salicyl-aldehyde (611) with 4-octyne using an Rh-DPPF complex gave the unsaturated ketone 612 in high yield [236], 

Thompson, Comprehensive Organic Synthesis, vol 3, p. 1015, Pergamon Press 1991. 

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