Palladium-catalyzed monocarbonylation

The 1,6-enyne 117 bearing a terminal isopropenyl underwent palladium-catalyzed monocarbonylation followed by the ene reaction via 118 to yield the six-membered ring 119 (Scheme 11 -33). The ensuing thermodynamically controlled olefin isomerization from 1,4-diene 119 to 1,3-diene affords the 1,3-cyclohexadiene 120 in 70% yield [31]. No further carbonylation of the intermediate allenyl germinal diester 118 to afford the triester corresponding to 65 in Scheme 11-18 occurs. Instead, the intramolecular ene reaction proceeds preferentially. The reaction took place smoothly at 50 °C under 1 atm of carbon monoxide. Pd(OAc)2 combined with dppp or dppf (1 1 ratio) is used as a suitable catalyst. 

Depending on the catalytic species, palladium-catalyzed mono- and dicarbonyl-ation of alkynes may be achieved. Monocarbonylation of acetylenic alcohols in the presence of thiourea is an elegant route to a-methylene-7-butyrolactone 202, the structure of which is widely distributed in certain natural products98,99). The synthesis of a vernolepine derivative (203) has been attempted by this method 100l Pro-... 

The carbonylation of butadiene, readily available from petroleum sources, yields a dicarbonylated adduct and dimer-carbonylated product, both desirable from a commercial standpoint. Palladium-catalyzed reactions yield monocarbonylated ... 

Carbonylation was applied in oligomerizations and polycondensations as well, even though most of the previous work focused on monocarbonylation reactions. Chaudhari and colleagues reported a palladium-catalyzed carbonylation-polycon-densation reaction of aromatic diiodides and aminohydroxy compounds [117]. With their methodology, alternating polyesteramides were prepared in chlorobenzene with l,8-diaza-bicyclo[5.4.0]undec-7-ene (DBU) as a base under 3 bar of carbon monoxide at 120 °C (Scheme 2.8). 

Cinnamic and acrylic amides become available in good yields by iron-catalyzed monocarbonylation of alkynes (Scheme 4-347). As catalyst, dodecacarbonyltriiron is employed in the presence of a bisimine ligand. The method is highly chemoselective and stereoselective. The a t/-Markovnikov product is formed, which is in contrast to most palladium-catalyzed carbonylations. ... 

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