Dihydrolevoglucosenone as a bio-based catalytic solvent for efficient reductive-transformation of CO2 with amines into formamides and benzothiazoles

Cyrene: a bio-based novel and sustainable solvent for organic synthesis

“…In 2022, Yu and coworkers proposed a protocol for the conversion of amines to formamides 63 , using CO 2 and PhSiH as the reductant. 37 They also successfully applied this protocol in the synthesis of benzothiazoles 65 from aminothiophenols 64 (Scheme 15). 37 Cyrene presented excellent results playing simultaneously the role of the solvent and the catalyst, perhaps due to its polarity.…”

“…The authors continued their study by examining the substrate scope realizing that electron-rich substituted anilines afforded higher yields, since the electron-rich benzene ring increases the nucleophilicity of the nitrogen atom, making the nucleophilic attack on silanes more favorable. 37…”

“…37 They also successfully applied this protocol in the synthesis of benzothiazoles 65 from aminothiophenols 64 (Scheme 15). 37 Cyrene presented excellent results playing simultaneously the role of the solvent and the catalyst, perhaps due to its polarity. Moreover, NMR mechanistic studies were carried out, indicating that Cyrene polarizes the N-C bond, making nitrogen a better nucleophile, thus enabling the reaction.…”

Cyrene: A Green Solvent for the Synthesis of Bioactive Molecules and Functional Biomaterials

“…A curious dual role of Cyrene as a solvent-catalyst can be found in the work of Yu and collaborators, who proposed the synthesis of formamides starting from amines and CO 2 in the presence of phenylsilane as a reductive agent (Scheme 14) [35]. Usually, organosilanes are used as reducing agents in combination with catalytic amounts of trifluoroacetic acid (TFA), Pd-, Rh-or boron-based catalysts, i.e., tris(pentafluorophenyl)borane).…”

Cyrene: a bio-based solvent for the Mizoroki–Heck reaction of aryl iodides

“…The dimerization reaction of sinapic ester 12 and the difluoromethylation reaction of heteroarenes or terminal alkynes 13 highlighted the beneficial use of Cyrene instead of other hazardous solvents. In many syntheses of different classes of molecules, such as isothiocyanates, 14 ureas, 15 bipyridines 16 and benzothiazoles, 17 Cyrene outperformed all other suitable solvents, offering a greener approach. Its industrial applicability was demonstrated when it was utilized in a large-scale Baylis–Hillman reaction.…”