49642-49-1Relevant articles and documents
Enantiopure Acetals of α-Alkynyl Carbonyl Compounds: Organoaluminum-Mediated 1,2-Shift of Cobalt-Complexed Alkynyl Group with Concomitant Capture by a Nucleophile
Taya, Kimiko,Nagasawa, Tetsuya,Suzuki, Keisuke
, p. 304 - 306 (1997)
Upon treatment with the organoaluminum-based combination of Lewis acid and nucleophile, chiral mesyloxy acetal having a Co-complexed alkynyl group undergoes stereospecific 1,2-shift of the complexed alkynyl and the concomitant attack of the ligand R of the organoaluminum reagent. Decomplexation of the products with CAN gives the chiral acetals of α-alkynyl carbonyl compounds in enantiomerically pure form in high yields.
Chemo- And regioselective hydroformylation of alkenes with CO2/H2over a bifunctional catalyst
Hua, Kaimin,Liu, Xiaofang,Wei, Baiyin,Shao, Zilong,Deng, Yuchao,Zhong, Liangshu,Wang, Hui,Sun, Yuhan
supporting information, p. 8040 - 8046 (2021/11/01)
As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway.
Insight into decomposition of formic acid to syngas required for Rh-catalyzed hydroformylation of olefins
Liu, Lei,Chen, Xiao-Chao,Yang, Shu-Qing,Yao, Yin-Qing,Lu, Yong,Liu, Ye
, p. 406 - 415 (2020/12/07)
Formic acid (FA) is one kind of important bulk chemicals, which is recognized as a sustainable and eco-friendly energy carrier to transport H2 via dehydrogenation or CO via decarbonylation. Expectantly, FA upon decomposition into H2 and CO could be used as the syngas alternative for hydroformylation. In this paper, the behaviors of FA to release H2 as well as CO following the distinct pathways were carefully investigated for the first time, and then established a new hydroformylation protocol free of syngas. It was found that the atmospheric hydroformylation of olefins with formic acid (FA) as syngas alternative was smoothly fulfilled over Xantphos (L1) modified Rh-catalyst under mild conditions (80 °C, Rh concentration 1 mol %, 14 h), resulting in >90% conversion of the olefins along with the high selectivity to the target aldehydes (>93%). By using FA as syngas source, the side-reaction of olefin-hydrogenation was greatly depressed. The in situ FT-IR and the high-pressure 1H NMR spectroscopic analyses were applied to reveal how FA behaves dually as CO surrogate and hydrogen source over L1-Rh(acac)(CO)2 catalytic system, based on which the deeply insight into the catalytic mechanism of hydroformylation of olefins with FA as syngas alternative was offered.
