Acid cyanides decarbonylation

Fragmentation of oxohydropurines such as hypoxanthine, xanthine and uric acid is similar to that of guanine, the main route involving elimination of hydrogen cyanide from N(l)—C(2), followed by ejection of CO and HCN. Xanthine and uric acid eject HCNO followed by decarbonylation (67JA2719, 62M632). Also see (B-72MI40902, p. 402) for a mass spectral study of N- and S-methylpurines. 

Increasing the temperature to 350 °C results in decarbonylation of the phenylpyruvic acid methyl ester derivatives and the phenyl acetic ester is formed with a ratio of 65 % a-ketoester to 35 % acetic acid ester. Until now the industrial process for the synthesis of phenylacetic acid ester has started from benzyl chloride, which is converted to benzyl cyanide by KCN, followed by hydrolysis. Every step of this reaction must be performed in a separate reactor and special measures must be taken for handling large amounts of toxic KCN. The new route is certainly an environmentally benign alternative [8,27]. 

Very closely related to decarbonylation of an -hydroxy acid is the Wohl degradation, in which an -hydroxy aldehyde is degraded to the aldehyde with one fewer carbon atoms. This starts from the oxime, which is converted by removal of water into the hydroxy nitrile, whence elimination of hydrogen cyanide — analogous to that of carbon monoxide and water from an -hydroxy acid — affords the lower aldehyde ... 

The reaction of carboxylic acid chlorides with low-valent metal complexes leads to the formation of acyl complexes, which can undergo decarbonylation to give a-bonded metal alkyls, alkenyls, or aryl complexes. This decarbonylation has been used to synthesize aiylsilanes from aryl acid chlorides in the presence of nickel(0) or palladium(0) complexes as catalysts. Similarly, acyl cyanides undergo decarbonylation with palladium(O) complexes to afford nitriles or alkenes, depending on the substrate. ... 

Analogous decarbonylation reactions were observed with acyl halides [18], esters [19], acyl cyanides [20], thioesters [21], selenoesters [21b], acylphospho-nates [22], and even ketones (preceding chapters). Acid anhydrides underwent a fragmentation reaction upon treatment with a nickel catalyst to afford alkenes,... 

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