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Title: Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis
Authors: Liu, Cuibo
Chen, Zhongxin
Yan, Huan
Xi, Shibo
Yam, Kah Meng
Gao, Jiajian
Du, Yonghua
Li, Jing
Zhao, Xiaoxu
Xie, Keyu
Xu, Haisen
Li, Xing
Leng, Kai
Pennycook, Stephen J.
Liu, Bin
Zhang, Chun
Koh, Ming Joo
Loh, Kian Ping
Keywords: Engineering::Chemical engineering
Issue Date: 2019
Source: Liu, C., Chen, Z., Yan, H., Xi, S., Yam, K. M., Gao, J., . . . Loh, K. P. (2019). Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis. Science Advances, 5(12), eaay1537-. doi:10.1126/sciadv.aay1537
Journal: Science Advances
Abstract: Unprotected E-hydrazone esters are prized building blocks for the preparation of 1H-indazoles and countless other N-containing biologically active molecules. Despite previous advances, efficient and stereoselective synthesis of these compounds remains nontrivial. Here, we show that Pt single atoms anchored on defect-rich CeO2 nanorods (Pt1/CeO2), in conjunction with the alcoholysis of ammonia borane, promotes exceptionally E-selective hydrogenation of α-diazoesters to afford a wide assortment of N-H hydrazone esters with an overall turnover frequency of up to 566 hours-1 upon reaction completion. The α-diazoester substrates could be generated in situ from readily available carboxylic esters in one-pot hydrogenation reaction. Utility is demonstrated through concise, scalable synthesis of 1H-indazole-derived pharmaceuticals and their 15N-labeled analogs. The present protocol highlights a key mechanistic nuance wherein simultaneous coordination of a Pt site with the diazo N═N and ester carbonyl motifs plays a central role in controlling stereoselectivity, which is supported by density functional theory calculations.
ISSN: 2375-2548
DOI: 10.1126/sciadv.aay1537
Rights: © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S.Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SCBE Journal Articles

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