A Facile One‐Pot Synthesis of 1,2,3‐Tri‐ and 1,1,2,3‐Tetrasubstituted Bis(guanidine)s from Bis(thiourea)s

Abstract

A facile and efficient one‐pot strategy for the preparation of 1,2,3‐tri‐ and 1,1,2,3‐tetrasubstituted bis(guanidine)s by starting from from readily available bis(thiourea)s has been successfully developed. The reaction provides products that contain a range of terminal and bridging groups. After a simple workup procedure, the products were obtained in analytically pure and in good to excellent yields.

Ethylene‐Bridged Tetradentate Bis(amidines): Supramolecular Assemblies through Hydrogen Bonding and Photoluminescence upon Deprotonation

“…This phenomenon was earlier observed for a tetradentate ( t ‐1,2‐DACH‐)bis(amidine)[7a] and the hexadentate congener 5 . Recently, a related bis(guanidine) featuring an n ‐propylene bridge has been reported that shows inter‐ and intramolecular hydrogen bonding as well …”

Ligands with Two Monoanionic N,N‐Binding Sites: Synthesis and Coordination Chemistry

“…These routes give rise to bis(guanidine)s with a different degree of substitution: although using the routes i ) to iii ), di‐, tri‐, and tetra‐substituted bis(guanidine)s are accessible, on route v ), di‐ and trisubstituted bis(guanidine)s have been prepared, and for the routes iv ) and vi ), all reports known to date are limited to trisubstituted compounds (R′=R′′=H). Overall, route i ), a one‐pot reaction with a simple workup procedure, is preferential because the related bis(thiourea)s are readily available and the desulfurization agent PbO can be recycled . However, in case of ethylene‐bridged bis(thiourea)s bearing terminal alkyl groups, N ‐(alkyl)‐4,5‐dihydro‐1 H ‐imidazol‐2‐amines are obtained instead of the desired bis(guanidine)s .…”

“…Overall, route i ), a one‐pot reaction with a simple workup procedure, is preferential because the related bis(thiourea)s are readily available and the desulfurization agent PbO can be recycled . However, in case of ethylene‐bridged bis(thiourea)s bearing terminal alkyl groups, N ‐(alkyl)‐4,5‐dihydro‐1 H ‐imidazol‐2‐amines are obtained instead of the desired bis(guanidine)s . If the terminal alkyl group is substituted by a sterically demanding aryl group, such as 2,6‐diisopropylphenyl, bis(guanidine)s are formed as a minor product, whereas 3,4‐ethylene‐bridged biguanides correspond to the main product .…”

Bis‐thiourea Derivatives and Their Utility in Synthesis of Mono‐heterocyclic, Bis‐heterocyclic, and Fused Heterocyclic Systems

“…Thus, reaction of bis‐thiourea derivative 14 with 20 equiv of pyrrolidine 183 and 2.1 equiv of PbO in toluene afforded the bis‐guanidine derivative 184 via desulfurization process. Various alkyl and aryl linker groups were tolerated under the applied reaction conditions (Scheme ) .…”