Carboxylative cyclization of propargylic alcohols with carbon dioxide: A facile and Green route to α-methylene cyclic carbonates

Liquid‐liquid‐phase Synthesis of exo‐Vinylene Carbonates from Primary Propargylic Alcohols: Catalyst Design and Recycling

“…The side-products cannot be assigned with certainty due to significant signal overlap in the proton NMR in the region δ H = 4.7-4.9 where the characteristic ring-opened product signals are expected to appear. The 13 C NMR suggests minor formation of products of type B, evidenced by the presence of the ketone signal at δ C = 204. We have previously shown that the carbamate group in a closely related EVC is unstable upon nucleophilic attack at cycliccarbonate moiety.…”

“…Ligands and precursors were worked-up in air, then dried, flushed with argon and stored in the glove box. NMR spectra were recorded on a Bruker AVANCE III 300 ( 1 H NMR: 300 MHz, 13 C NMR: 75 MHz, 31 P NMR: 122 MHz), a Bruker AVANCE III 400 ( 1 H NMR: 400 MHz, 13 C NMR: 101 MHz) or a Bruker AVANCE III 500 ( 1 H NMR: 500 MHz, 13 C NMR: 126 MHz) spectrometer at the Institute of Organic Chemistry/Heidelberg University. Chemical shifts (δ) are given in ppm relative to the residual solvent peak or to TMS.…”

“…1 H NMR (500 MHz, CDCl 3 ): δ 7.38 (d, J = 7.3 Hz, 1H), 7.24 (t, J = 7.5 Hz, 1H), 7.11-7.04 (m, 1H), 7.01 (t, J = 7.2 Hz, 1H), 3.10-3.02 (m, 4H), 1.94-1.85 (m, 2H), 1.84-1.71 (m, 4H), 1.65 (br s, 4H), 1.58-1.52 (m, 2H), 1.40 (br s, 2H), 1.33-1.00 (m, 30H), 0.86 (t, J = 6.7 Hz, 6H). 13 6, 29.3, 27.5, 27.5-27.3 (m), 26.6, 26.4, 22.7, 14 General method for the carboxylative cyclisation of propargyl alcohol. Propargyl alcohol (291 μl; 280 mg; 5 mmol), mesitylene (232 μl; 201 mg; 1.67 mmol), the relevant silver carboxylate salt (0.05 mmol) and phosphine ligand (0.05 mmol) were added to a Premex autoclave in air.…”

“…We have shown that the conversion of primary propargylic alcohols to unsubstituted EVCs – unattainable using previously reported catalytic systems – can be achieved by using Buchwald‐type phosphine ligands or the N‐heterocyclic carbene ligand IPr paired with AgOAc [4,13] . We attempted to deliver a immobilised system on solid supports, incorporating these catalyst requirements (see SI section 2).…”

“…We have shown that the conversion of primary propargylic alcohols to unsubstituted EVCs -unattainable using previously reported catalytic systems -can be achieved by using Buchwald-type phosphine ligands or the N-heterocyclic carbene ligand IPr paired with AgOAc. [4,13] We attempted to deliver a immobilised system on solid supports, incorporating these catalyst requirements (see SI section 2). Heterogeneous strategies included: immobilisation of the silver catalyst onto anionic supports (clays, poly(acrylate)s), metal oxides (silica, alumina), sulfonation of XPhos to immobilise onto anion-exchange resins, and covalent-linkage of the catalyst via the NHC ligand to polystyrene supports.…”