09 Apr 02:50
by Toni Hille, Torsten Irrgang, Rhett Kempe
Abstract
Benzimidazoles and quinoxalines are important N-heteroaromatics with many applications in pharmaceutical and chemical industry. Here, the synthesis of both classes of compounds starting from aromatic diamines and alcohols (benzimidazoles) or diols (quinoxalines) is reported. The reactions proceed through acceptorless dehydrogenative condensation steps. Water and two equivalents of hydrogen are liberated in the course of the reactions. An Ir complex stabilized by the tridentate P^N^P ligand N2,N6-bis(di-isopropylphosphino)pyridine-2,6-diamine revealed the highest catalytic activity for both reactions.
Aromatic diamines were reacted with alcohols and diols to form benzimidazoles or quinoxalines, respectively (see scheme). In the course of the reactions, water and two equivalents of hydrogen gas were eliminated/liberated. An Ir complex stabilized by a tridentate P N P ligand was found to be an efficient catalyst in these reactions.
25 Mar 02:12
by Shuanglin Qu, Yanfeng Dang, Chunyu Song, Mingwei Wen, Kuo-Wei Huang and Zhi-Xiang Wang
Journal of the American Chemical Society
DOI: 10.1021/ja411568a
25 Mar 02:12
by Ken-ichi Fujita, Yui Tanaka, Masato Kobayashi and Ryohei Yamaguchi
Journal of the American Chemical Society
DOI: 10.1021/ja5001888
19 Mar 13:31
by Denis Chusov, Benjamin List
Abstract
A method of reductive amination without an external hydrogen source is reported. Carbon monoxide is used as the reductant. The reaction proceeds efficiently for a variety of carbonyl compounds and amines at low catalyst loadings and is mechanistically interesting as it does not seem to involve molecular hydrogen.
Look, no H2! Reductive amination without an external hydrogen source has been developed using carbon monoxide as the reductant and rhodium acetate (0.2–1 mol %) as catalyst. The method tolerates a variety of functional groups and provides target amines in good to excellent yields.
27 Dec 08:57
by Andrew J. Neel, Jörg P. Hehn, Pascal F. Tripet and F. Dean Toste
Journal of the American Chemical Society
DOI: 10.1021/ja407410b
21 Nov 02:22
by Qin-Heng Zheng, Wei Meng, Guo-Jie Jiang and Zhi-Xiang Yu
Organic Letters
DOI: 10.1021/ol402517e