Issue 41, 2021

Hydroboration of carbonyls and imines by an iminophosphonamido tin(ii) precatalyst

Abstract

A novel three-coordinated tin(II) chloride [Ph2P(NtBu)2]SnCl (1) supported by an N,N′-di-tert-butyliminophosphonamide having two phenyl groups on the phosphorus atom was synthesized by the reaction of the starting lithium iminophosphonamide [Ph2P(NtBu)2]Li with SnCl2·(dioxane) in toluene. The molecular structure of 1 was established by X-ray diffraction analysis. Tin(II) chloride 1 can act as an efficient precatalyst for the hydroboration of a wide variety of aldehydes, ketones, and imines at −10 °C. DFT calculations propose that hydroboration involves hydride transfer from the corresponding tin(II) hydride intermediate [Ph2P(NtBu)2]SnH (10) to the carbonyl substrates via four-membered transition states (TS-12), affording three-coordinated tin(II) alkoxide intermediates [Ph2P(NtBu)2]SnOR (13), followed by the stepwise reaction of 13 with HBpin (pin = pinacolate) to release the boronate esters and regenerate the tin(II) hydride 10. The stoichiometric reaction of the in site-generated 10 with benzophenone 2a at −10 °C led to the formation of 13. Moreover, 13 also stoichiometrically reacted with HBpin at −10 °C, forming the corresponding boronate ester 3a and 10 based on the 1H NMR spectrum of the reaction mixture.

Graphical abstract: Hydroboration of carbonyls and imines by an iminophosphonamido tin(ii) precatalyst

Supplementary files

Article information

Article type
Paper
Submitted
07 jun 2021
Accepted
10 set 2021
First published
13 set 2021

Dalton Trans., 2021,50, 14810-14819

Author version available

Hydroboration of carbonyls and imines by an iminophosphonamido tin(II) precatalyst

K. Nakaya, S. Takahashi, A. Ishii, K. Boonpalit, P. Surawatanawong and N. Nakata, Dalton Trans., 2021, 50, 14810 DOI: 10.1039/D1DT01856F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements