ß-Borylalkenyl Z- e Isomerization in Rhodium-Mediated Diboration of Nonfunctionalized Internal Alkynes

Galván Curto, S. (Universidad de Zaragoza) ; Esteruelas, M.A. ; Oliván, M. ; Oñate, E. ; Vélez, A.

Resumen: The elemental steps for the preparation of (E)-pinBC(Me)=C(Me)Bpin (Bpin = pinacolboryl) by means of the anti addition of B2pin2 to 2-butyne, promoted by the boryl complex Rh(Bpin){xant(PiPr2)2} (1; xant(PiPr2)2 = 9, 9-dimethyl-4, 5-bis(diisopropylphosphino)xanthene), have been analyzed from a kinetic point of view, and the intermediates of the process, the ß-borylakenyl complexes Rh{(Z)-C(Me)=C(Me)Bpin}{xant(PiPr2)2} (2) and Rh{(E)-C(Me)=C(Me)Bpin}{xant(PiPr2)2} (3), have been isolated and fully characterized. The key step for the formation of the diborylalkene is the transformation of 2 into 3 as a result of the Z-E isomerization of the ß-borylalkenyl group, which takes place via metallacyclopropene intermediates. The isomerization is sterically controlled, and the pincer diphosphine adapts its coordination mode to the requirements of the process happening to act as ¿2-P, P. The Z-E isomerization of the ß-borylalkenyl ligand of 2 is slower than the oxidative addition of the diborane to 1. As a consequence, under catalytic conditions, the formation of the syn-addition product (Z)-pinBC(Me)=C(Me)Bpin is favored, although the intermediate Rh(Bpin)3{xant(PiPr2)2} is much less stable than 2.

Idioma: Inglés

DOI: 10.1021/acs.organomet.8b00259

Año: 2018

Publicado en: Organometallics 37, 12 (2018), 1970-1978
ISSN: 0276-7333

Factor impacto JCR: 4.1 (2018)

Categ. JCR: CHEMISTRY, ORGANIC rank: 11 / 57 = 0.193 (2018) - Q1 - T1
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 5 / 45 = 0.111 (2018) - Q1 - T1

Factor impacto SCIMAGO: 1.473 - Inorganic Chemistry (Q1) - Physical and Theoretical Chemistry (Q1) - Organic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E06-17R
Financiación: info:eu-repo/grantAgreement/ES/DGA/FSE
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2016-81797-REDC
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2017-82935-P

Tipo y forma: Artículo (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)