Publication: Hydroboration of carbonyls and imines by an iminophosphonamido tin(ii) precatalyst
Issued Date
2021-11-07
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ISSN
14779234
14779226
14779226
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2-s2.0-85118226328
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Mahidol University
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SCOPUS
Bibliographic Citation
Dalton Transactions. Vol.50, No.41 (2021), 14810-14819
Suggested Citation
Kazuki Nakaya, Shintaro Takahashi, Akihiko Ishii, Kajjana Boonpalit, Panida Surawatanawong, Norio Nakata Hydroboration of carbonyls and imines by an iminophosphonamido tin(ii) precatalyst. Dalton Transactions. Vol.50, No.41 (2021), 14810-14819. doi:10.1039/d1dt01856f Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/76577
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Title
Hydroboration of carbonyls and imines by an iminophosphonamido tin(ii) precatalyst
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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. This journal is