Hoesch synthesis

Hoesch synthesis A variation of the Gattermann synthesis of hydroxy-aldehydes, this reaction has been widely applied to the synthesis of anthocyanidins. It consists of the condensation of polyhydric phenols with nitriles by the action of hydrochloric acid (with or without ZnCl2 as a catalyst). This gives an iminehydrochloride which on hydrolysis with water gives the hydroxy-ketone. 

The methoxy group of methoxythiophenes shows a reactivity which, in many respects, differs appreciably from the reactivity of the corresponding anisoles. Thus, in an attempted Hoesch synthesis with 5-methoxy-2-thenylcyanide (167) and phloroglucinol, the methoxy group reacted instead and 5-(2, 4, 6 -trihydroxyphenyl)-2-thenyl cyanide (168) was obtained. 2-Thenyl cyanide reacts normally in the Hoesch synthesis, Likewise, upon acid hydrolysis of the reaction product of 5-methoxy-2-thienyllithium with benzophenone, (169) was obtained instead of the expected substituted methoxythiophene. No defined products could be isolated from the attempted Claisen rear-... 

Houben-Hoesch synthesis orgchem Condensation of cyanides with polyhydric phenols in the presence of hydrogen chloride and zinc chloride to yield phenolic ketones. hit-ban harsh sin-tha-sas ... 

Many nitriles have been used. Even aryl nitriles give good yields if they are first treated with HC1 and ZnCl2 and then the substrate added at 0°C.357 In fact, this procedure increases yields with any nitrile. If thiocyanates RSCN are used, thiol esters ArCOSR can be obtained. The Gatterman reaction (1-16) is a special case of the Hoesch synthesis. 

RSCN are used, thiol esters ArCOSR can be obtained. The Gatterman reaction (11-18) is a special case of the Hoesch synthesis. 

Acylations with Nitriles. With particularly reactive aromatic nuclei such as phenols, a Friedel-Crafts type reaction may be effected with nitriles in the presence of an acid catalyst such as hydrogen chloride, aluminum chloride, or zinc chloride. The reaction is usually called the IIouben-Hoesch synthesis.700 When hydrogen cyanide is employed, the process leads to aromatic aldehydes even with a number of aromatic... 

REACTIONS USING NITRILES — THE HOUBEN-HOESCH SYNTHESIS... 

REACTIONS USING NITRILES —THE HOUBEN-HOESCH SYNTHESIS 747... 

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