13492-07-4Relevant articles and documents
A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
supporting information, p. 1552 - 1566 (2019/06/14)
Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
Process for producing optically active compound
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Page/Page column 6, (2008/06/13)
A process for producing an optically active compound based on the hydrolysis of an alkenyl ester compound or the cleavage of an alkenyl ether compound. The process uses neither an acidic compound nor a basic compound, and rectants can be reacted in a high concentration. It does not necessitate a buffer, nutrient, etc. unlike enzymatic reactions or reactions using a microorganism. It is a simple process which attains a satisfactory production efficiency. The process, which is for producing an optically active carboxylic acid or optically active alcohol represented by the general formula (VI): (wherein R1, R2, and R3 are different groups; and A represents methylene, carbonyl, or a single bound), is characterized by causing water to act on an alkenyl ester or alkenyl ether represented by the general formula (I): (wherein R4, R5, and R6 each represents hydrogen, alkyl, etc.) in the presence of a specific transition metal complex having an optically active ligand.
Effective nonenzymatic kinetic resolution of (±)-trans-2-arylcyclohexanols using 3β-acetoxyetienic acid, DCC, and DMAP
Matsugi, Masato,Hagimoto, Yuri,Nojima, Masatomo,Kita, Yasuyuki
, p. 583 - 584 (2013/09/05)
(1R,2S)-trans-2-Arylcyclohexanols of high enantiomerically purity were obtained by the simple stirring of the corresponding (±)-arylcyclohexanols with 3β-acetoxyetienic acid, DCC, and DMAP at room temperature.
