Regioselective Palladium(II)-Catalyzed Synthesis of Five- or Seven-Membered Ring Lactones and Five-, Six- or Seven-Membered Ring Lactams by Cyclocarbonylation Methodology

Abstract

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)(H 2 O)] + BF 4 -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.

Palladium‐catalysed cyclocarbonylation reactions in dimethyl carbonate, an eco‐friendly solvent and ring‐opening reagent

“…9,10 A few years ago we reported that the combination of palladium acetate (Pd(OAc) 2 ) and 1,4-bis-(diphenylphosphino) butane (dppb) formed an efficient homogeneous catalytic system for the selective cyclocarbonylation of allyl phenols and other bis-allyl phenols. 11,12 The reaction afforded new important five-, six-and sevenmembered ring lactones (Scheme 1) and it has been noted that the solvent can play an important role in terms of yield and regioselectivity: in toluene, for example, the seven-membered ring lactone was the major product; in dichloromethane, the six-and five-membered lactones were favoured.…”

Synthesis of Heterocycles by Transition Metals-Catalyzed Cyclocarbonylation Reactions

“…Proton attack from X and metal elimination affords cyclic carbonyl compounds D [see refs. 24,28,33,39,72,89].…”

“…According to a recent study cyclocarbonylation of 2-allylphenol derivatives, using Pd(OAc)2 and dppb as catalytic system, gave mixture of five, six and seven membered ring lactones (Scheme 31) [39].…”

Cyclocarbonylation reactions of allylphenols and allylnaphthols catalyzed by Pd/C– 1,4‐bis(diphenylphosphine)butane

“…1,2 In 1996, one of us described the regioselective cyclocarbonylation of 2-allylphenol derivatives, using palladium acetate [Pd(OAc) 2 ] and 1,4-bis(diphenylphosphino)butane (dppb) as a homogeneous catalytic system, for the synthesis of five-, six-or seven-membered ring lactones, and it was found that the selectivity of the process was dependent on the solvent and CO/H 2 ratio. 3 More recently, the previously mentioned catalytic system has been validated for the synthesis of a large variety of molecules, such as bis-lactones and estrone derivatives. 4,5 To our knowledge, very few examples of heterogeneous catalysis are reported in the literature for this class of reaction.…”