No abstract

2-Alkynylnitriles are a distinguished class of molecules known to play a pivotal role in the construction of a plethora of carbo-/heterocyclic compounds of biological and pharmaceutical importance. These molecules have been exploited as hydrolytically stable irreversible labels for cysteine tagging. In addition, they also form an important homologous series of complex interstellar molecules identi-fied by radioastronomy. Therefore, in this Minireview, we highlight the numerous transformations and diverse reactions carried out with these substrates. Different reactions including nucleophilic additions and various carbo-/heterocycles formation are the prime focal areas of this article. Mechanistic aspects for certain reactions have also been delineated. Scheme 1. Synthesis of 3-phenyl-2-propynylnitrile (3) using cyanogen bromide as cyanating agent.Scheme 2. Synthesis of various 2-alkynylnitrile derivatives employing phenyl cyanate (4) as cyanating agent.

We report an efficient and straight forward access to nitrile substituted enol esters via ionic liquid [BMIM]OH mediated hydrocarboxylation of alkynylnitriles under mild conditions. This atom economical transition metal-free protocol gives an easy access to a variety of such enol esters with excellent regio and Z-stereoselectivity. Reusability of [BMIM]OH without losing of significant amount of yield is another noticeable feature of this article.

A practical and straightforward strategy for the synthesis of 3-acylimino-3H-1,2-dithiol derivatives via a metal-free annulation reaction of alkynylnitriles with thiocarboxylic acids mediated by ionic liquids [BMIM]Br has been reported. This operationally simple protocol offers an easy and rapid access to a library of dithiol derivatives in moderate to good yields. The mechanistic studies show a benzoyldithio anion addition to alkynylnitriles followed by an annulation reaction through the involvement of a disulfide moiety as the key intermediate.

An atom‐economical approach for the synthesis of 3‐aminofurans/thiophenes via a conjugate addition of alcohols and thiols with electron withdrawing groups (EWGs) at α positions on alkynenitriles followed by a modified Thorpe‐Ziegler cyclization have been reported. This operationally simple protocol offers a rapid access to a library of 3‐aminofurans/thiophenes in moderate to good yields.