Synthesis of Highly Basic Hexasubstituted Biguanides by Environmentally Friendly Methods

Abstract

A series of hexasubstituted biguanides was synthetized employing nonconventional and environmentally friendly methods. Their properties were studied computationally (basicity) and experimentally (basicity and catalytic properties in transesterification reaction).

Cycloaddition of Thiourea- and Guanidine-Substituted Furans to Dienophiles: A Comparison of the Environmentally-Friendly Methods

“…5 unable to determine due to similar solubilities of the diene and cycloadduct. 6 Approximately 40 % of the Achmatowicz-like product was also obtained as a product of oxidation. 7 Isolated after the washing with diethylether.…”

“…In continuation of our interest in guanidine-type of superbases [5,6], we were attracted by the paper of Calmes and coworkers who proved that cycloaddition could be a good approach toward chiral diamines [7]. They also suggested that such diamines could be excellent building blocks for synthesis of novel bifunctional catalysts or used as ligands.…”

Mechanochemical N-alkylation of imides

“…In recent time, important progress was made in the development of various solvent-free organic reactions [5], especially by the use of the ball milling technique [6–8]. In continuation of our interest in eco-friendly organic syntheses [9–14], we studied mechanochemical N -alkylation reactions of imides with alkyl halogenides, and the results are presented in this paper. Until now, ball milling N -alkylations of ureas [15], hydrazones [16], imines [17–18], pyridines [19], pyrimidines [20], imidazoles [21], secondary amines [22], as well as allylic alkylation reactions [23] were reported in the literature.…”

The Synthesis and Structural Characterization of Peralkylated Triguanide Superbases

“…tri-, tetra-, and heptaguanide), [4] has not been followed by an equally successful development of synthetic methods in the field. While preparative chemistry of biguanides is well documented and spans from conventional procedures [6] to more environmentallyfriendly methods, [7] reports on the synthesis of higher analogues such as triguanides [8a] and tetraguanides still remain scarce with only a few examples found in the patent literature. [8b-f] Our group has recently made a contribution towards the synthesis, structure, and reactivity of pentasubstituted triguanide derivatives.…”

“…[20] For this purpose, we followed a standard procedure and tested the benzyl triguanide derivative 4a in a transesterification reaction with methanol (see the Supplementary Material for details). Although the synthesized triguanides are predicted to be very strong bases, the catalytic activity of 4a in the transesterification reaction is lower than, for example N 1 ,N 2 -dicyclohexyl-N 4 ,N 4 ,N 5 ,N 5 -tetramethylbiguanide (DCTMB) or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), [7] which are weaker bases (Fig. 3).…”