Journal of the American Chemical Society, Vol.118, No.18, 4264-4270, 1996
Regioselective Palladium(II)-Catalyzed Synthesis of 5-Membered or 7-Membered Ring Lactones and 5-Membered, 6-Membered or 7-Membered Ring Lactams by Cyclocarbonylation Methodology
2-Allylphenols react with carbon monoxide and hydrogen in the presence of catalytic quantities of a cationic palladium(II) complex [(PCy(3))(2)Pd(H)(H2O)](BF4-)-B-+ or palladium acetate and 1,4-bis(diphenylphosphino)butane, affording five- or seven-membered ring lactones (bicyclic, tricyclic, and pentacyclic) as the principal products, often in excellent yields. Use of 2-aminostyrenes as reactants and catalytic quantities of palladium acetate and tricyclohexylphosphine, affords five-membered ring lactams in high yield and selectivity. Bicyclic and tricyclic heterocycles containing six-membered ring lactams can be synthesized from the reaction of 2-allylanilines with CO/ H-2 using the catalytic system Pd(OAc)(2)/PPh(3), while use of 1,4-bis(diphenylphosphino)butane instead of PPh(3) in the latter process results in the formation of the seven-membered lactams benzazepinones in good yield, The regiochemical control depends on the nature of the palladium catalyst, the relative pressures of the gases, and the solvent.
Keywords:EFFICIENT SYNTHESIS;CARBONYLATION;CYCLIZATION;COMPLEX;HETEROCYCLES;TEMPERATURE;DERIVATIVES;ACIDS