Selenocyanates reaction with carboxylic acids

Reaction of carboxylic acids with selenocyanates or N-PSP in the presence of trialkylphosphine... 

It has been reported that aryl selenocyanate (25 Scheme 7) reacts with carboxylic acids in the presence of tributylphosphine under mild conditions, giving rise to selenol esters in good yields. The process may involve the reaction of carboxylic acids with selenophosphonium salt (26), which is the key intermediate. 

Alkyl selenides are most conveniently prepared by the dialkylation of Na2Se or by the monoalkylation of selenolates. Common routes to aryl derivatives include the reaction of a selenolate with a diazonium salt, the SrnI reactions described earlier, and the reaction of aryUithiums with aryl selenocyanates (ArSeCN). A different approach employs the reaction of alcohols with aryl selenocyanates or N-(phenylseleno)phthalimide (see Section 6) in the presence of tri-n-butylphosphine. Similar conditions can also be used to convert carboxylic acids to selenoesters (8). These reactions are illustrated in Scheme 3. 

Conversion of O-alkyl esters to their corresponding mefhylselenoesters by treatment with dimethylaluminum methylselenolate has also been reported [29]. Preparation of selenoesters directly from carboxylic acids is accomplished by reaction with selenocyanates [30] or N-PSP (N-phenylselenophthalimide) [31] in the presence of trialkylphosphine. Yields of selenoesters prepared from N-PSP and BujP are usually higher than those obtained by use of ArSeCN and BU3P (Scheme 15.9). 

Displacement of OH by an ArSe group. Reaction of aryl selenocyanates with alcohols, aldehydes or carboxylic acids to give alkyl aryl selenides, homologation of aldehydes or esters of arylselenols. 

Similarly, reaction of hydrazidoyl halides with sodium cyanate ( ), potassium selenocyanate and sodium azide has been reported. For example, decarboxylation occurs when the carboxylic acid derivative XLIV is treated with sodium azide, and the tetrazole derivative XLVI is isolated... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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