Diene monoxides, coupling reactions

Allyl carbonates (Scheme 5) and diene monoxides (Eq. 32) were also employed in the palladium-catalyzed coupling reaction of arylsilanes 136, 37]. The reaction does not require activation by a fluoride ion or an additional base like a hydroxide ion. 

Scheme 10-11 Mechanism of regiocontrol for coupling reactions of allylic carbonates and diene monoxide in the absence of fluoride ion.

In another metal-mediated coupling reaction, the highly functionalized dienes 136a and 136b were allowed to react with Ni(PPh3)4 in the presence of excess zinc/copper couple at 50 ""C and 1 atm of carbon monoxide to provide the octakis(methoxycarbonyl) 137a and the tetrabenzo derivatives 137b in excellent yields (77 and 84%, respectively), (see Scheme 17 compare also Scheme 12 for the formation of the related [4]radialene 10686-88) 373 s treated with excess LiBr H2O in HMPA at temperatures... 

The first palladium-catalyzed copolymerization of carbon monoxide (CO) with olefins was described in 1982 [11], and as a consequence, carbonylative coupling reactions with alkenes were reported soon after. Notably, it was Negishi and Miller who discovered the first two examples of intramolecular carbonylative Heck reactions of 1-iodopenta-1,4-dienes by applying stoichiometric amounts of palladium [12]. 5-Methylenecyclopent-2-enones as the products were produced in moderate yields (Scheme 7.1). 

CCV with carbon monoxide causes a ligand-ligand coupling reaction to produce the diketone (CCVI) (Takahashi et al., 1967). Nickel(II) salts are also effective for the coupling between 1,3-dienes and active methylene... 

Vinylic triflates such as 244 also allow the introduction of C-bonded substituents reaction with dilithium diallylcopper cyanide gives the 1,4-diene 245 in 76% yield,232 and Stille coupling with tributylvinyltin and carbon monoxide in the presence of palladium(O) produces the dienone 246 in 71% yield.233 234... 

A number of related reactions, which occur by different mechanisms, have been reported. The intramolecular reaction of halo-malonates under carbon monoxide gives cyclic ketones (Eq. 5) [31,32]. This proceeds by mechanism C. Halo-malonates also couple with unsaturated compounds such as 1,3-dienes... 

Tris(allyl)rhodium(in) was reported to react with the hydroxyl-terminated surfaces of silica, titania and alumina to form a surface bis(allyl)rhodium(III) fragment, which on reaction with carbon monoxide afforded hexa-1,5-diene in quantitative fashion by reductive coupling of two allyl ligands. 

---