Rate constants and Arrhenius parameters for H-atom abstraction from Bu3SnH by the 2,2-dimethylvinyl radical in PhMe. Kinetic evidence for an entirely free radical mechanism for the O-directed hydrostannation of alkynols with stannanes and Et3B/O2

Watson, HA, Hale, KLE, Marron, JM, Manaviazar, S, Fielding, AJ ORCID: 0000-0002-4437-9791 and Hale, KJ ORCID: 0000-0002-6756-8763 (2025) Rate constants and Arrhenius parameters for H-atom abstraction from Bu3SnH by the 2,2-dimethylvinyl radical in PhMe. Kinetic evidence for an entirely free radical mechanism for the O-directed hydrostannation of alkynols with stannanes and Et3B/O2. Organic & Biomolecular Chemistry, 23 (17). pp. 4106-4115. ISSN 1477-0520

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Abstract

Using the 2,2-dimethylvinyl radical 6 as a horological calibrant for the α-cyclopropyl-β-tributylstannylvinyl radicals 2a and 13 in PhMe, the k values and Arrhenius parameters for their cyclopropane ring-openings have been estimated by competition kinetics over a 293–353 K temperature range. The high log A values (14.95 and 14.55) for these reactions only satisfactorily align with a unimolecular, β-scissive, EH1 radical ring-opening being rate-determining, and the radicals 3a (R = Bu) and 14 undergoing H-atom abstraction from the stannane to give 4a and 15. The log A data for these two reactions only endorse a totally free radical mechanism for the O-directed free radical hydrostannation of dialkyl acetylenes with stannanes and Et3B/O2. An estimated kH-atom abstraction Bu3SnH PhMe 293 K of 1.96 × 108 mol−1 s−1 is proposed for 6 in PhMe, along with an estimated kH-atom abstraction Ph3SnH PhMe 293 K of 1.36 × 109 mol−1 s−1.

Item Type:	Article
Uncontrolled Keywords:	3405 Organic Chemistry; 34 Chemical Sciences; 0304 Medicinal and Biomolecular Chemistry; 0305 Organic Chemistry; Organic Chemistry; 3404 Medicinal and biomolecular chemistry; 3405 Organic chemistry
Subjects:	Q Science > QD Chemistry R Medicine > RS Pharmacy and materia medica
Divisions:	Pharmacy and Biomolecular Sciences
Publisher:	Royal Society of Chemistry (RSC)
Date of acceptance:	7 March 2025
Date of first compliant Open Access:	1 September 2025
Date Deposited:	01 Sep 2025 10:40
Last Modified:	01 Sep 2025 10:45
DOI or ID number:	10.1039/d4ob01846j
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27065

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