Different Reaction Patterns in the Baylis-Hillman Reaction of Aryl Aldehydes with Phenyl Vinyl Ketone, Phenyl Acrylate and Phenyl Thioacrylate
In the Baylis-Hillman reaction of aryl aldehydes with phenyl vinyl ketone we have observed exclusive formation of diadducts 4, and that the yields of diadduct can reach 80% with increasing amounts of phenyl vinyl ketone. On the other hand, for phenyl acrylate and phenyl thioacrylate, only the normal Baylis-Hillman adduct was obtained. The effects of substituents were also examined and a plausible reaction mechanism is proposed for the formation of compounds 4.
A unique cascade reaction between 3-arylprop-2-inylcarboxylates and benzaldehydes leading to the formation of Morita-Baylis-Hillman adducts.
During an alkyne-carbonyl metathesis reaction between electron-rich 3-arylprop-2-inylcarboxylates and electron-poor benzaldehydes, a smooth migration of carboxylate groups takes place. This unique cascade reaction allows the formation of Morita-Baylis-Hillman (MBH) adducts unavailable via a traditional MBH reaction.
On the Baylis–Hillman reaction of acrylate, acrylonitrile, and acrolein with some non-enolizable α-dicarbonyl compounds: synthesis of phytotoxic bipolaroxin models
The Baylis–Hillman reaction of acrylonitrile, methyl acrylate, and acrolein with several cyclic α-dicarbonyl compounds was investigated. Whereas acrylonitrile reacted with most of these ketones, giving good yields of the expected 1′-cyanovinyl carbinols, the more sterically demanding methyl acrylate failed to undergo the reaction. Attempted Baylis–Hillman reaction of acrolein with the 1,2-dicarbonyl substrates usually resulted in polymers but, in two cases, the desired α-substituted acroleins were obtained. An alternative route to such compounds was developed, employing a Grignard – allylic oxidation sequence. In bioassays, some of the products, embodying the functionality believed responsible for the phytotoxicity of the sesquiterpene bipolaroxin, inhibited germination of lettuce seeds. This activity diminished with time. Keywords: Baylis–Hillman, acrylonitrile, acrylate, acrolein, α-dicarbonyl, bipolaroxin, phytotoxicity.