Imidoyl chlorides reduction

A new, mild method for acyl exchange in amides involves conversion to the imidoyl chloride, reduction to the imine [LiAl (OBu )3H], and acylation with an acid chloride. ... 

When sulfuryl chloride was used in this reaction instead of POCI3 or PCI3, imidoyl chlorides 17 were isolated as the products (89KGS120). By reduction of 17 with Na2S205 aryl methyl tellurides 18 are formed which readily eliminate a molecule of methyl chloride to give 2-arylbenzotellurazoles 12 (R = Ar) in 40-65% yields. 

Stannous chloride is used most frequently for the reduction of nitro compounds [177, 178, 179] and of quinones [180, 181], It is also suitable for conversion of imidoyl chlorides [182] and of nitriles [183] to aldehydes, for transformations of diazonium salts to hydrazines [184], for reduction of oximes [f[Pg.30]

Reduction of Amidines, Thioamides, Imidoyl Chlorides and Hydrazides 171... 

REDUCTION OF AMIDINES, THIOAMIDES, IMIDOYL CHLORIDES AND HYDRAZIDES... 

TaUe30 Reduction of amidiiies, thioaiiiiiles, imidoyl chlorides and hydrazides... 

Nucleophilic substitutions at the azepine nucleus are confined mainly to derivatives of hydroazepines such as lactim ethers, imidoyl chlorides and amidines, and to hydride ion reductions of carbonyl and imine groups (see Section 5.16.3.5.2). In addition some transan-nular nucleophilic displacements have been described, but such reactions are not as common with azepines as with larger ring heterocycles. 

Deamination ofRNHI.t> A new method for reductive deamination of primary amines (1) involves conversion to an aromatic imidoyl chloride (2), which is converted to the hydrocarbon by Bu,SnH and AIBN (10, 412-413). Yields are satisfactory in the deamination of benzylamine, but are only moderate in the reaction of simple alkylamines. 

Amides have been converted into imidoyl chlorides and then reduced to aldimines with LiAlH(OBu ).3, as in Scheme 15. Although not claimed as a synthesis of aldehydes, the aldimines can be hydrolyzed to aldehydes quite readily. Interestingly, the authors say that an excess of the reducing agent can be used because further reduction to the amine requires 24 h, whereas the first stage to the aldimine requires only 30 min at -78 C. 

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... 

Table 13 Aldehydes Synthesized by the Reduction of Imidoyl Chlorides using SnCh (Sonn-Miiller) or CrCb ...

Finally, treatment of amides with phosphorus oxychloride gives Vilsmeier complexes, which are often formulated as A-alkylated imidoyl chlorides (59). Irrespective of their precise nature, it has been found that they can be converted very efficiently to aldehydes by reduction with zinc followed by aqueous work-up (Scheme 17). Although the method has only been used for benzaldehyde and a number of chlorinated and brominated analogs, the yields reported are consistently high (87-97%). ... 

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. 

Reductive deamination can be performed in reasonable yields via phenylimidoyl chlorides prepared from benzoyl derivatives of primary amines. Imidoyl chloride derivatives decompose on heating with TBTH and AIBN in xylene to yield alkanes (equation 80) . Primary amines can also be reductively deaminated in high yields via isocyanide derivatives. Formylation-dehydration transforms an amino group into an isocyanide quite routinely. Reductive removal of isocyanide can be performed with sodium naphthalenide in hydrocarbon solvents " or with TBTH in the presence of AIBN ". The TBTH reduction works equally well for primary, secondary and tertiary isocyanides and yields are good (equation 81) ". ... 

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