16958-25-1Relevant articles and documents
Cu-catalyzed enantioselective conjugate additions of alkyl zinc reagents to unsaturated N-acyloxazolidinones promoted by a chiral triamide phosphane
Hird, Alexander W.,Hoveyda, Amir H.
, p. 1276 - 1279 (2003)
A chiral triamide phosphane promotes highly efficient and enantioselective Cu-catalyzed conjugate additions of alkyl zinc compounds to unsaturated oxazolidinones (see scheme). The resulting β-alkyl chiral oxazolidinones are readily converted into synthetically useful carbonyl compounds not accessible by alternative catalytic methods.
Meyers,Kamata
, p. 1603 (1974)
Characterization of chlorinated valepotriates from Valeriana jatamansi
Lin, Sheng,Zhang, Zhong-Xiao,Chen, Tao,Ye, Ji,Dai, Wei-Xing,Shan, Lei,Su, Juan,Shen, Yun-Heng,Li, Hui-Liang,Liu, Run-Hui,Xu, Xi-Ke,Wang, Hui,Zhang, Wei-Dong
, p. 185 - 193 (2013)
HPLC-PDA-MS and TLC analysis were used to look for minor cytotoxic chlorinated valepotriates from whole plants of Valeriana jatamansi (syn. Valeriana wallichii DC.). This resulted in isolation of 15 chlorinated valepotriates, designated as chlorovaltrates A-O, together with six known analogues, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1,5-dihydroxyvalechlorine, volvaltrate B, chlorovaltrate, rupesin B, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5- hydroxyvalechlorine, and (1R,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5- hydroxyvalechlorine. Their structures were elucidated by spectroscopic methods including homo- and heteronuclear two-dimensional NMR experiments. Chlorovaltrates K-N, chlorovaltrate and rupesin B showed moderate cytotoxicity against lung adenocarcinoma (A 549), metastatic prostate cancer (PC-3M), colon cancer (HCT-8) and hepatoma (Bel 7402) cell lines with IC50 values of 0.89-9.76 μM.
Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids
Yang, Shuang,Che, Wen,Wu, Hui-Ling,Zhu, Shou-Fei,Zhou, Qi-Lin
, p. 1977 - 1980 (2017/03/09)
We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF?) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
Highly enantioselective copper-phosphoramidite-catalyzed conjugate addition of dialkylzinc reagents to acyclic α,β-unsaturated imides
Pineschi, Mauro,Del Moro, Federica,Di Bussolo, Valeria,Macchia, Franco
, p. 301 - 304 (2007/10/03)
A new and practical way to introduce an alkyl fragment in the β-position of aliphatic carboxylic acid derivatives with high enantioselectivities by the use of a commercially available chiral ligand is reported. N-Acylpyrrolidinones, as simple derivatives