Palladium-Catalyzed Cross Coupling Reaction Of Benzylic Chlorides, Carbon Monoxide And Allylstannane

a,P-Unsaturated carbonyl compounds were widely used in organic synthetic chemistry. Due to their special structures, which were used in many reactions, such as Michael addition reaction, Nazarov cyclization and Rauhut-Currier reaction (dimerization). Traditional methods for the synthesis of unsaturated carbonyl compounds include aldol condensation, Perkin reaction, Claisen-Schmidt reaction, malonic ester synthesis, Knoevenagel condensation reaction, Meyer-Schuster rearrangement. In addition,β-hydroxy aldehyde or ketone can be easily dehydrated toα,β-unsaturated aldehyde or ketone, which is a common method for the synthesis of such compounds.In this paper, palladium-catalyzed cross coupling reaction of benzylic chlorides, carbon monoxide and allylstannane is studied. The coupling reaction provides a simple and efficient method for the carbonylation of benzylic chlorides and the synthesis ofα,β-unsaturated ketone.1. The coupling reaction of 1-(chloromethyl)-2-methylnaphthalene, carbon monoxide and allylstannane was selected as the model reaction. And the catalyst, pressure, solvent, temperature were optimized.1 atm CO,5 mmol% Pd(PPh3)4,1,4-dioxane as solvent,24 h was found as the best condition. Under the condition, 1-(2-methylnaphthalen-1-yl)pent-3-en-2-one was obtained in 86% yield. Under the same condition described above, the coupling reaction of various benzylic chlorides, carbon monoxide and allylstannane were performed, and the products were obtained in 63%-88% yield.2. Other benzylic chlorides were also performed in the condition,63% to 88% yield was afford. Due to the strong electron withdrawing group, the double allylation product was obtained after the coupling reaction of 1-(chloromethyl)-4-nitrobenzene, carbon monoxide and allylstannane.