DESign of Sustainable One-Pot Chemoenzymatic Organic Transformations in Deep Eutectic Solvents for the Synthesis of 1,2-Disubstituted Aromatic Olefins

Abstract

The self-assembly of styrene-type olefins into the corresponding stilbenes was conveniently performed in the Deep Eutectic Solvent (DES) mixture 1ChCl/2Gly under air and in the absence of hazardous organic co-solvents using a one-pot chemo-biocatalytic route. Here, an enzymatic decarboxylation of p-hydroxycinnamic acids sequentially followed by a ruthenium-catalyzed metathesis of olefins has been investigated in DES. Moreover, and to extend the design of chemoenzymatic processes in DESs, we also coupled the aforementioned enzymatic decarboxylation reaction to now concomitant Pdcatalyzed Heck-type CC coupling to produce biaryl derivatives under environmentally friendly reaction conditions.

Combination of Enzymes and Deep Eutectic Solvents as Powerful Toolbox for Organic Synthesis

“…In this framework, the application of ChCl/U 1:2 DES as cosolvent, in combination with water, enabled the efficient synthesis of the desired styrenes, under mild conditions and with high substrate loadings [ 119 ]. The synthetic relevance of the methodology was later underlined by the successful implementation of tandem transformations, in which the biocatalytic step was followed by a Pd-catalyzed Heck cross-coupling or a Ru-catalyzed olefin metathesis, in the same water–DES reaction environment [ 120 , 121 ].…”

Deep Eutectic Solvents as à-la-Carte Medium for Transition-Metal-Catalyzed Organic Processes

“…A total of 17 examples of coupling products were reported with good-to-excellent yields, with the catalysts and DESs being recyclable up to five times without any loss in the catalytic activity [ 61 ]. Regarding the Heck coupling, González-Sabín and García-Álvarez described the one-pot chemoenzymatic decarboxylation of p -hydroxicynnamic acid, followed by a Pd(PPh 3 ) 4 -catalyzed Heck reaction with PhI in a mixture of ChCl:glycerol:water (1:2:1, Figure 25 ) [ 62 ].…”

Advances and Applications in Deep Eutectic Solvents Technology

“…Lately, special attention has been devoted to the pursuit of sustainable catalytic reactions [159][160][161][162], and especially to transition-metal-mediated processes in DESs, with applications in Pd-catalyzed cross-coupling [163], Cu-catalyzed Ullmann type [164], Rucatalyzed redox isomerization [165,166] and metathesis reactions [167]. Notwithstanding the increased sustainability in several cases, a distinct impact of the DES with respect to conventional systems (e.g., enhanced catalytic activity), is difficult to be addressed in the aforementioned examples.…”