Synthesis of ortho-Phenylenebis(guanidine) Derivatives with Potential Chirality

We report the synthesis and potential chirality of ortho-phenylenebisguanidines (BGs) with substituents at C(3) and C(6). Guanidinylation of 3,6-disubstituted benzene-1,2-diamines with 2-chloro-4,5- dihydro-1,3-dimethyl-1H-imidazolium chloride gave the corresponding BGs. X-Ray crystallography showed that the two guanidine moieties occupy different faces of the benzene ring, creating potential chirality, although optical resolution of tBu-substituted BG by chiral HPLC failed. However, a methylated acyclic bisguanidinium salt (BGms) was obtained as a chiral crystal with a space group of P2(1)2(1)2(1).