Issue 44, 2023

Trialkylphosphonium oxoborates as C(sp3)–H oxyanion holes and their application in catalytic chemoselective acetalization

Abstract

The use of trialkylphosphonium oxoborates (TOB) as catalysts is reported. The site-isolated borate counter anion in a TOB catalyst increases the availability of C(sp3)–H to interact with electron donor substrates. The catalytic protocol is applicable to a wide range of substrates in the acetalization reaction and provides excellent chemoselectivity in the acetalization over thioacetalization in the presence of alcohols and thiols, which is otherwise hard to achieve using typical acid catalysts. Experimental and computational studies revealed that the TOB catalysts have multiple preorganized C(sp3)–Hs that serve as a mimic of oxyanion holes, which can stabilize the oxyanion intermediates via multiple C(sp3)–H non-classical hydrogen bond interactions.

Graphical abstract: Trialkylphosphonium oxoborates as C(sp3)–H oxyanion holes and their application in catalytic chemoselective acetalization

Supplementary files

Article information

Article type
Edge Article
Submitted
16 Jun 2023
Accepted
15 Oct 2023
First published
20 Oct 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 12684-12692

Trialkylphosphonium oxoborates as C(sp3)–H oxyanion holes and their application in catalytic chemoselective acetalization

V. M. Leung, H. F. Wong, C. Pook, Y. S. Tse and Y. Yeung, Chem. Sci., 2023, 14, 12684 DOI: 10.1039/D3SC03081D

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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