Nitrile imines, alkenyl

Nitrile imines can have the alkenyl group attached at either end of the 1,3-dipole, through carbon or nitrogen. Predominantly 1,3-cyclizations have been observed although a few 1,1 -cyclizations have been reported. 

In the review period, most syntheses of phosphonic acids and their derivatives involved simple organophosphorus reagents, like diallq l and trialkyl phosphites that were widely used in reactions with aHqmes and alkenes including bromoalkenes to obtain alkenyl and allqmylphospo-nates as well as with imines, ketimines, ketones, aldehydes and nitriles to afford imino- and aminophosphonates, and hydroxyphosphonates. Two or more component reactions were also utilised in these syntheses. 

Furthermore, the asymmetric catalysis of 27 could accommodate vinylogous aza-enamines as a source of an alkenyl unit, and the use of 27d bearing the 2,6-dimethyl-4-(l-adamantyl)phenyl groups as catalyst led to the establishment of the general and highly enantioselective formal alkenylation of N-benzoyl imines [77]. Since the oxidative transformation of an aza-enamine moiety of the product into a nitrile functionality appeared feasible as described above, this method offered facile access to optically active y-amino a,P-unsaturated nitriles (Scheme 7.50). 

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