Vinyl halides with carbonyls

Vinyl halides (example 17, Table VII) were first observed by Kroper to form acrylic esters by reaction with carbon monoxide under pressure and tetracarbonylnickel in methanol at 100°C. These reactions were later shown to occur under much milder conditions. Highly stereospecific reactions were observed c/s-vinyl halides gave cis-carbonylation products and trans-vinyl halides trans-carbonylation products (example 18, Table VII). Retention of configuration of alkyl substrates in carbonylation seems to be a general feature in carbon monoxide chemistry (193a). 

Further examples using polycyclic, skeletal systems with various trapping agents including alkyl halides, vinyl halides and carbonyl compounds and others can be found in refs 8, 269, 377-382, 846, 929 yields were moderate. 

F.i. Reactions of Aryl and Vinyl Halides with Metal Carbonylates... 

Later, in 1991, Suzuki and colleagues developed another methodology for the carbonylative coupling of vinyl halides with organoboranes using Pd(PPh3)4 and K3PO4 as a base [10] to synthesize vinyl ketones in moderate to excellent yields (Scheme 4.3). However, the chemoselectivity dropped and a mixture of... 

The palladium-catalysed reaction of vinylic halides with alkenes to form carbonyl compounds can be useful synthetically. Acrolein acetals can act as substrates in the presence of amines to form dienals in protected form [equation (34)].Addition of terminal vinylic iodides to enones is also possible,... 

The positive results achieved in developing aminocarbonylation protocols prompted the evaluation of other nucleophiles in similar microwave-promoted carbonylations. Surprisingly, few reports concerning the direct carbonylation of aryl or vinyl halides with hydrazides to the corresponding N,N -diacylhydrazines are found in the literature and an effort was made to modify the previously reported aminocarbonylation protocol [17] for the carbonylative synthesis of N, /-diacylhydrazines [19]. 

A. number of rutro compounds used m ndturdl product synthesis have been prepared by the n of alkyl halides Some recent examples are summarized m Table 2 4 fi-Nitro carbonyl compounds are important for synthesis of natural products The reaction of alkyl vinyl ketones with sodium nitrite and acetic acid in THF gives thecorrespondmgfi-nitro carbonyl compounds in42-82% ""rhis method is better for the preparation of fi-nitro carbonyl compounds than the nitration of the corresponclmg halides... 

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. ... 

Alkenyl trifluoromethanesulphonates (enol triflates) undergo Heck coupling with alkenes efficiently (equation 123)209a 215. This reaction is a useful variation of the use of vinyl halides not only because they are easy to prepare from the corresponding carbonyl compounds, but also because yields are good, and the stereochemistry of the triflate is largely maintained. 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

Alkyl halides possessing / -hydrogens are usually poor substrates for carbonylative cross-coupling due to competitive / -hydride elimination/ Allyl chlorides can be used in carbonylative cross-coupling with allylstannanes/ phenyl-, 3-furyl, or vinylstannanes " to afford allylketones in modest to good yields. Divinylketones can be accessed through the reaction of vinylstannanes with vinyl iodides or vinyl triflates, with the latter requiring the addition of LiCl. Synthetic potential of this method has been proved in the formation of macrocyclic ketone jatrophone. In the reaction of vinyl triflates with tetramethyltin or aryltrimethylstannanes the additional activation by ZnCle is required. 

Enol Ethers and Esters 0-15 O-Alkylation of carbonyl compounds with diazo alkanes 0-17 Transetherification 0-20 Reaction between acyl halides and active hydrogen compounds 0-23 Transesterification 0-24 Acylation of vinylic halides 0-94 Alkylation with ortho esters 0-107 O-Acylation of 1,3-dicarbonyl compounds... 

The palladium-catalyzed carbonylation of isomeric vinylic halides shows the reaction to be reasonably stereospecific and proceed with retention of the original halide structure. The degree of specificity, however, depends somewhat on the reaction conditions. Low reaction temperatures and/or excess triarylphosphine favor the stereospecific reaction (11). 

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