Carbonylation aryl/vinyl halides

In addition to intermolecular carbonylations, there are intramolecular reactions that allow for the synthesis of various heterocycles. As a prime example, the intramolecular alkoxy- or aminocarbonylation (cyclocarbonylation) of hydroxyl-or amino-substituted aryl/vinyl halides enables the synthesis of lactones, lactams, oxazoles, thiazoles, imidazoles, etc. [229]. 

Palladium complexes also catalyze the carbonylation of halides. Aryl (see 13-13), vinylic, benzylic, and allylic halides (especially iodides) can be converted to carboxylic esters with CO, an alcohol or alkoxide, and a palladium complex. Similar reactivity was reported with vinyl triflates. Use of an amine instead of the alcohol or alkoxide leads to an amide. Reaction with an amine, AJBN, CO, and a tetraalkyltin catalyst also leads to an amide. Similar reaction with an alcohol, under Xe irradiation, leads to the ester. Benzylic and allylic halides were converted to carboxylic acids electrocatalytically, with CO and a cobalt imine complex. Vinylic halides were similarly converted with CO and nickel cyanide, under phase-transfer conditions. ... 

CARBONYLATION OF ARYL AND VINYL HALIDES LEADING TO CARBOXYLIC ACIDS AND RELATED COMPOUNDS... 

Acetylenic ketones.3 PdCl2(dppf) is generally the most satisractory catalyst for synthesis of acetylenic ketones by carbonylation of aryl and vinyl halides in the presence of a terminal acetylene. 

This review attempts to provide an overview of microwave-promoted metal-catalyzed transformations of aryl and vinyl halides (or pseudo halides), providing a personal selection of both pioneering and very recently published work. Covered areas include carbonylative transformations, Heck and Sono-gashira reactions, nucleophilic substitutions and cross-couplings. Because of the diversity of the microwave systems used, the reader should consult the original references for detailed descriptions of settings and instrumentation. 

In the organometallic field the reaction of R3Sn ions (R = CH3, Ph) with aromatic and aliphatic substrates has been reported. Another example is the substitution of aryl or vinyl halides by iron(I) porphyrins under electrochemical induction43, and the electrochemical arylation of metal carbonyl anions to form C5H5(CO)3M—cr—Ar (M = W, Mo Ar = Ph, C6H4N02)4b. 

The photostimulated carbonylation of aryl and vinyl halides by Co(CO)4" ions under phase-transfer catalysis conditions [Co2(CO)8, C6H6/NaOHaq, CO, Bu4N+Br", 65 °C] has been reported211,212. Thus PhBr, o- and /7-bromo toluenes, /7-bromoanisole, p-bromofluorobenzene, 4-bromoacetophenone and 1- and 2-bromonaphthalenes gave ArC02Na in 90-98% yields. Under the conditions used, carbonylation did not occur with unsubstituted PhCl, but when it was substituted, as in / -chlorobenzoic acid, or p-chlorophenylacetic acid, carbonylation was quantitative (98% yield). 

A Pd(ll) catalyst system with an oxazoline ligand 44 has been described that allows the desymmetrization of meso-Z-alkyl-2-propargylcyclohexane-l,3-diols in an asymmetric cyclization-carbonylation reaction. The products which contain a chiral quaternary carbon were obtained in excellent yields with high ee s (Scheme 56) <2006T9988>. 7-Hydroxy terminal <2005JOC3099> and internal <2006TL2793> alkenes can be converted to tetrahydrofurans by Pd(0)-catalyzed carboetherification reactions combined with a coupling of aryl or vinyl halides. 

The boroxines could then be subjected to Suzuki coupling with aryl, vinyl, or benzyl halides. Suzuki coupling with tri- -butylstannyl chloride also gave the tri- -butylstannyl-substituted thiophenes 221. These can form the starting materials for further transformations. The carbonylative coupling with halides resulted in the formation of ketones tin-lithium exchange followed by reaction with electrophiles led to a host of other useful products (Scheme 65). 

Acetylenic ketones. PdChfdppf) is the pn ferred catalyst for the carbonylation of vinylic and aryl halides in the presence of terminal alkynes to form acetylenic ketones (equation 1). 

---