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|Title:||Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis||Authors:||Liu, Cuibo
Yam, Kah Meng
Pennycook, Stephen J.
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.||URI:||https://hdl.handle.net/10356/144004||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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