Five-Membered Selenium-Nitrogen Heterocycles

Five-Membered Selenium Heterocycles WITH One Nitrogen Atom 

Very few syntheses of isoselenazoles are reported. The parent compound and its 3-methyl derivative (1) were prepared by Wille et al by ring closure of 3-selenocyanatoacrolein and the corresponding butenone in liquid ammonia [Eq. (1)]. 

Using the basic features of this reaction shown in Eq. (2), other derivatives of the ring system have been prepared  

Recently Weber and Renson reported that the reaction of -chloro-a,)8-disubstituted crotonaldehyde with methylselenomercaptan gave ji-methylseleno-a, -disubstituted crotonaldehydes, which were subsequently cyclized with bromine and ammonia to give the isoselenazoles (2). [Eq. (3)]. 

Several isoselenazolium perchlorates (3) were prepared by Liebscher and Hartmann by treating 4-RC6H4CCI = CHCH = NMe CIO4 with NaSeCN and 4-R CeH4NH2. 

Five-Membered Selenium Heterocycles with One Nitrogen Atom 

in Organic Selenium Compounds Their Chemistry and Biology (D. L. [dayman and W. H. H. Gunther, eds.), p. 459. Wiley (Interscience), New York, 1973. 

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Lalezari I (1984) Five membered selenium-nitrogen heterocycles. In Katritzky AR, Rees CW (eds) Comprehensive heterocyclic chemistry I. Pergamon, Oxford, chap 4.20, p 334... 

The heterocycles which are the subject of this chapter were treated in the first edition of Comprehensive Heterocyclic Chemistry (CHEC-I) <84CHEC-I(6)947> five-membered selenium-nitrogen heterocycles are found in <84CHEC-l(6)333>, whereas the tellurazoles were not included. 

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