Phosgene-pyridine salt

This phosgene-pyridine salt can react with other amines. For example, with aziridine, a stoicheiometric amount of pyridine is displaced to produce pyridinium chloride and equimolar amounts of pyridine and 2-chloroethyl isocyanate [2042b]. 

The originally proposed 1 2 structure (II) for the phosgene-pyridine adduct was deduced by analogy to the commonly observed 1 1 pyridinium salt (I) as shown in scheme 118. However, as a conclusion of a study of low temperature NMR and solid-state CP/MAS spectra, King Jr. and coworkers (Ref. 170) assigned a dihydropyridine-pyridinium (2-DHPP) structure (III) to the 1 2 salt. 

This procedure is a modification of preparations of 3-phen)d, sydnone described earlier. The dehydration of N-nitroso-N phenylglycine has also been effected by the use of thionyl chloride and pyridine in dioxane, thionyl chloride in ethertrifluoroacetic anhydride in etherand diisopropylcarbodiimide in water or by reaction of the alkali metal salts of N-nitroso-N-phenylglycine with phosgene or benzenesulfonyl chloride in water or with acetyl chloride in benzene. ... 

On the other hand, vV-aryl-//-nitrosoaminonitriles undergo interesting secondary reactions. Under acidic conditions, salts of the sydnonimes form (Eq. 13) under basic conditions, a rearrangement to an isomeric oxime takes place, which, on treatment with phosgene in pyridine leads to 4-substituted-3-cyano-l,2,4-oxadiazolinones (Eq. 14) [26b],... 

Perhydro-oxazolo[3,4- ]pyridines have long been prepared by condensation between the appropriate piperidyl-2-carbinol and an aldehyde or ketone. For example, the antidepressant spiropiperidine derivative (135) is obtained by the reaction between a-phenyl-2-piperidine methanol and N-benzyl-4-piperidone (81USP4260623). Perhydro-oxazolo[3,4-a]pyridin-3-one (136) is obtained by phosgenation of 2-(hydroxymethyl)piperidinium p-toluene sulfonate followed by cyclization of the resultant chloroformate salt by treatment with triethylamine in dichloromethane. This ring system... 

Diaryl carbonates are made from the reaction of phosgene with two molar equivalents of the particular sodium phenolate [3]. However, the direct conversion of phenols can be achieved by reaction of phosgene in the presence of quaternary ammonium salts, or acid acceptors (such as pyridine), at ambient temperatures [2016]. The three dihydroxybenzenes... 

In contrast, the reaction of pyridine Al-oxide, or its 3-methyl or 4-methyl derivative) with phosgene in dichloromethane, in the absence of added base, gives hydrolytically unstable carbonate salts [811aa] ... 

Pyridyl methacrylate has been prepared from the sodium salt of 2-pyridone and methacryl chloride and has been polymerized by radicals but not by anions. 2-Pyridone and phosgene (1 4) in dry tetrahydrofuran or benzene with or without pyridine form di-(a-pyridyl)carbonate, which is a useful reagent for the formation of the benzoate and the monophenyl phosphate of 2-pyridone. ... 

Chloroethyl isocyanate 174 is the major product obtained when aziridine is allowed to react with an equivalent amount of 1 1 triethylamine-phosgene complex 175 [108] or 2 1 pyridine-phosgene complex 177 [109]. Aziridine carbamoyl chloride 176 was postulated as a transient intermediate in this reaction. Attempts to trap this elusive species as the triethylammonium or pyridinium salt have been unsuccessfiil [109]. 

Ethyl a-(a-naphthylacetyl)acetoacetate added to a soln. of phosgene in toluene, ice-salt cooled, treated dropwise with pyridine, stirred 2 hrs. in the cold, and the product isolated the next morning cyclic carbonate of the starg. m. Y 51%. F.e. s. K.-H. Boltze and K. Heidenbluth, B. 92, 986 (1959). 

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