Novel application of phosphonium salts as co-catalysts for the Baylis–Hillman reaction

Effect of Anchimeric Assistance in the Reaction of Triphenylphosphine with α,β‐Unsaturated Carboxylic Acids

“…Substrates having α‐ and, especially, β‐substituents require more forcing reaction conditions, and attempts to involve them in phosphine‐catalyzed transformations under normal temperature or pressure are usually unsuccessful . A number of methods have also been developed to improve the rate of the Morita–Baylis–Hillman reaction using microwave and ultrasound irradiation, Lewis acids , protic additives , ionic liquids , etc. Another promising strategy is based on the concept of hydrogen bonding, when substrates or catalysts are functionalized in a specific manner by proton‐donor groups .…”

Phosphine-catalyzed synthesis of β-lactones from ketenes and chiral β-oxyaldehydes

“…We speculate that the preference for anti-stereochemistry across the -lactone ring may be due to an anti-periplanar arrangement in the transition state involving enolate A/B and the aldehyde or, alternatively, a 7-membered cyclic transition state in which the phosphonium ion of B activates the aldehyde carbonyl to nucleophilic attack by the enolate of B. 14,18 Figure 1. Rationale of diastereoselectivity in reaction of chiral βoxyaldehydes.…”

Recent Advances in the Morita-Baylis-Hillman Reaction Under Microwave Irradiation

“…1) [16][17][18][19][20][21][22][23][24][25][26], several protocols have been proposed to accelerate this reaction, such as the use of ultrasound [27], addition of salts [28], high pressure [29], ionic liquids [30][31][32] and microwave irradiation. MBHR are usually slow and the reaction may take from days to weeks for completion depending on the reactivity of the activated alkene, electrophile and catalyst.…”