Synthesis of Chiral Bicyclic Guanidinium Salts using Di(imidazole-1-yl)methanimine

A detailed account of the synthesis of chiral bicyclic guanidinium salts is presented. This work represents the first systematic investigation of an approach toward the challenging target molecules via a key guanylation step employing di­(imidazole-1-yl)­methanimine (<b>6</b>) followed by a two-fold cyclization, which resulted in guanidinium salts <b>8</b> and <b>10</b>. Factors governing the regioselectivity of the final cyclization step are discussed based on further data obtained in the course of the attempted syntheses of two additional bicyclic guanidinium salts