830-09-1Relevant articles and documents
Lipase-catalyzed synthesis of 4-methoxy cinnamoyl glycerol
Patil, Dipak,Dev, Bappaditya,Nag, Ahindra
, p. 5 - 8 (2011)
Cinnamoyl esters are used as organic ultraviolet (UV) filters in sunscreens and cosmetic formulations. To avoid any possible harmful effects from chemically synthesized product, the enzymatic synthesis appears to be an excellent way to satisfy the present consumer demand for natural products. Enzymatic esterification of 4-methoxy cinnamic acid (4MCA) with glycerol was carried out in organic solvents using immobilized lipase B from Candida antarctica, in which the maximum conversion of 34% was found in isooctane at 70 °C after 24 h with 12% of enantiomeric excess. If the reaction continued for longer times (48 h) it leads to the formation of 16% of diester along with 56% of monoester. The results of enzymatic esterification were compared with reported chemical esterification and the present method was found to be superior in terms of conversion yields and priority to the formation of monoester. Synthesized monoester product was isolated and characterized by spectroscopic techniques.
Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions
El Ali, Bassam,Fettouhi, Mohammed,Iali, Wissam,Mansour, Waseem,Suleiman, Rami
, (2021/08/09)
A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.
Water-initiated hydrocarboxylation of terminal alkynes with CO2and hydrosilane
Wang, Meng-Meng,Lu, Sheng-Mei,Paridala, Kumaraswamy,Li, Can
supporting information, p. 1230 - 1233 (2021/02/09)
This work discloses a Cu(ii)-Ni(ii) catalyzed tandem hydrocarboxylation of alkynes with polysilylformate formed from CO2and polymethylhydrosiloxane that affords α,β-unsaturated carboxylic acids with up to 93% yield. Mechanistic studies indicate that polysilylformate functions as a source of CO and polysilanol. Besides, a catalytic amount of water is found to be critical to the reaction, which hydrolyzes polysilylformate to formic acid that induces the formation of Ni-H active species, thereby initiating the catalytic cycle.