Azomethine ylides, alkenyl cyclizations

Intramolecular cycloaddition can be carried out on a variety of alkynyl azomethine ylides analogous to reactions of the alkenyl azomethine ylides. There is also one report of cyclization with an allene. 

A chiral selenophosphoramide catalyst was employed for the intramolecular cyclization of an alkenyl sulfonamide to achieve the enantioselective formation of N-heterocycles including an azepane derivative via a mechanism proposed to include formation of a three-membered sulfur-containing ring (14JA8915). A [4 + 3]-cycloaddition reaction of methyl coumalate 12 with an azomethine ylide, formed from imine esters 13 yielded functionalized azepine derivatives 14 (14OL4508). 

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