Aldehyde synthesis Gattermann

Gattermann aldehyde synthesis, 9, 2 Gattermann-Koch reaction, 5, 6 Germanes, addition to alkenes and alkynes, 13, 4 Glycals,... 

Gattermann Aldehyde Synthesis (Gattermann-Adams Formylation)... 

Pyrroles and furans also undergo the Gattermann aldehyde synthesis with HC1 and HCN, furan gives furfuraldehyde and 2-methylindole gives 2-methylindole-3-carboxaldehyde. The Houben-Hoesch ketone synthesis is also applicable to the preparation of acyl derivatives of furans and pyrroles, e.g. ethyl 2,4-dimethylpyrrole-3-carboxylate with MeCN and HC1 yields (81). 

GATTERMANN ALDEHYDE SYNTHESIS. Preparation of aldehydes of phenols, phenol ethers, or heterocyclic compounds hy treatment of the aromatic substrate with hydrogen cyanide and hydrochloric acid in the presence of Lewis acid catalysts. 

Phenolic ketones may be prepared by the Hoesch acylation reaction, which may be regarded as an extension of the Gattermann aldehyde synthesis (Section 6.10.1, p. 990). The procedure involves reaction of a nitrile with a phenol (or phenolic ether) in the presence of zinc chloride and hydrogen chloride best results are usually obtained with polyhydric phenols or their ethers, as for example in the preparation of phloroacetophenone (Expt 6.125). The formation of phenolic ketones by means of the Fries rearrangement of phenolic esters with aluminium chloride is discussed on p. 976. 

In a related reaction, the Gattermann aldehyde synthesis, the carbon monoxide of the previous reaction is replaced by hydrogen cyanide (Scheme 6.6). This reaction gives poor yields with benzene itself, but is successful with activated species such as aryl ethers and phenols. The reaction proceeds via an aryl imine and the mechanism is not dissimilar to that of the Vilsmeier-Haack reaction. 

Gattermann aldehyde synthesis Hydrogen cyanide. Zinc chloride. 

When the Gattermann aldehyde synthesis (hydrogen cyanide-zinc chloride) is applied to some benzyl alkyl or aryl ketones, isoquinolines are formed [2268]. Application of the Schmidt reaction to tra/u-dibenzoylstilbene at a temperature slightly above that of the surroundings converts it into a 4-benzoylquinoline [2216]. Care should be exercised with the use of hydrazoic acid. The acetal... 

Triazine can also be used as a hydrogen cyanide source in the Gattermann aldehyde synthesis. The corresponding aldehydes are formed on treatment of electron-rich pyrrole or furan derivatives 16,29 or aryl Grignard reagents, e. g. 18,30 with 1,3,5-triazine (1). 

Aromatic hydrocarbons and aryl halides can be converted into sulfinic acids in yields averaging 80% if the reaction is carried out at low temperature, if, as in the Gattermann aldehyde synthesis, reaction is initiated by passing in dry hydrogen chloride, and if the tetrachloroaluminum sulfinate formed is decomposed, not by acid, but by alkali, and acid is used for the first time to decompose the alkali sulfinites thus formed.240 Aryl ethers give sulfinic acids even in the cold, but reaction readily proceeds further to give sulfoxides and sulfonium compounds 241... 

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