Sonn-MUller reduction

One of the classical reductive aldehyde syntheses is the Sonn-MUller reduction of imidoyl chlorides. The method is closely related to the Stephen reduction described in the previous section. As shown in Scheme 16, substrates (53) may be prepared either by the treatment of anilides with phosphorus pentachloride or sulfinyl chloride, or less usually via the Beckmann rearrangement. They are... 

The amides and hydrazides of pyridine-carboxylic acids arc of some importance, though their chemistry is not marked by unusual properties. Nicotinamide is, of course, an important compound, and isonicotinic acid hydrazide (isoniazid) is an antitubercular drug. Substituted derivatives are used as antidepressants. In general, however, these compounds show normal chemical behaviour. The amides undergo hydrolysis, dehydration and Hofmann bromination without difficulty. Their reduction has been much studied as a route to pyridine aldehydes. The Sonn-Muller reduction is not very satisfactory in this series, but the McFadyen-Stevens reaction is useful . Nicotinic acid diethylamide gives only poor yields of the aldehyde upon reduction with lithium aluminium hydride, but yields from the methyl-phenylamide are high. Most satisfactory is the reduction of nicotinic acid dimethylamide with lithium diethoxyaluminium hydride . 

SONN MULLER Aldehyde synthesis Aldehyde synthesis from amides or ketoximes, by reduction of irmno chiondes. 

This is redueed with anhydrous SnCl2 to RCH=NH, which precipitates as a complex with SnC and is then hydrolyzed (16-2) to the aldehyde. The Stephen reduction is most successful when R is aromatic, but it can be done for aliphatic R up to about six carbons. It is also possible to prepare 21 in a different way, by treating ArCONHPh with PCI5, which can then be converted to the aldehyde. This is known as the Sonn-Muller method. 

Sonn-Muller method. Preparation of aromatic aldehydes from anilides by conversion of an acid anilide with phosphorus pentachloride to an imido chloride, reduction of the imido chloride with stannous chloride, and hydrolysis of the obtained anil. 

Phenanthrene-9-aldehyde has been obtained by the Sonn and Muller synthesis from 9-phenanthroyl chloride, by the Rosen-mund reduction of 9-phenanthroyl chloride, by the Gatterman... 

The synthesis of aldehydes from imidoyl chlorides via reduction and hydrolysis of the azomethine has been demonstrated by Sonn and Muller who used stannous chloride as the reducing agent. 

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