Primary amides phosgene

Scheme 160 Reactions of oxalyl chloride and phosgene with primary amides.

In the reactions with N-substituded amides, phosgene generaiiy acts as a chiorinating agent yo give Viismeier salts (see volume 2). As in the case of primary amides, the use of N-silyi amides is often required to observe N-acyia-tion in reasonable yields. 

When primary amides are combined with phosgene, an efficient dehydration occurs to... 

Under pressure, and with an excess of phosgene in the presence of HCl, primary amides give pyrimidine derivatives [2226a] ... 

Because phosgene reacts with primary amide groups to yield nitriles, especially in the presence of bases, the NCAs of glutamine (1183a) and asparagine (1183b) cannot be prepared by the phosgenation of these amino acids. 

Isatoic anhydride itself (91-1), when allowed to react with the primary amine (91-2), gives the corresponding amide (91-3), again with the expulsion of carbon dioxide. Treatment of the intermediate with phosgene results in the formation of a quinazolodione ring. There is thus obtained the serotonin blocking compound doperidone (91-4) [101], which is described as a sedative. 

Phosgene and tertiary carboxylic acid amides form very labile adducts (17 equation 6 not yet isolated or used for preparative purposes as such), which decompose with loss of CO2 very rapidly to give amide chlorides (see Section 2.7.2.2.1.i). Decomposition with evolution of CO2 is a common fate of primary adducts of carbonic acid chloride derivatives. Primary adducts from DMF and chloroformic acid esters (18), for example, decompose immediately to give alkoxymethyleneiminium chlorides, which react to give alkyl chlorides and DMF (equation 7). Adducts (19) from secondary and tertiary carboxamides... 

Phosgene, as well as the easier to handle diphosgene (chloroformic acid trichloromethyl ester) or triphosgene (carbonic acid bis(trichloromethyl) ester) transform primary, secondary and tertiary amides and thioamides to chloromethyleneiminium chlorides (25 equation 15), whereby the reaction with thioamides is of broader scope and proceeds with fewer side reactions. The amide chlorides derived from primary and secondary amides can lose HCl, giving nitriles or imidoyl halides, respectively. /V-Sub-stituted formamides can be converted to isonitriles via amide halides. ... 

Although there are many alternative routes for the synthesis of isocyanates [24] (see also Chapter 4), none are as simple or as attractive as the carbonylation of primary amines with phosgene. This is reflected by the widespread employment of phosgene in the industrial manufacture of isocyanates the use of phosgene continues despite numerous attempts to And suitable alternatives (see Chapter 4). However, acyl isocyanates such as 10 cannot normally be prepared by the reaction of phosgene with the corresponding carboxylic acid amide, since the phosgene... 

The preparation of amides by the treatment of amines with acyl haUdes is a very general reaction. When phosgene is the acyl hahde, both aliphatic and aromatic primary amines or their salts give carbamoyl chlorides, which can be regarded as substituted chloroformamides, CICONHR. 

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