Tonks, Ian A. and Meier, Josef C. and Bercaw, John E. (2013) Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II). Organometallics, 32 (12). pp. 3451-3457. ISSN 0276-7333. doi:10.1021/om400080g. https://resolver.caltech.edu/CaltechAUTHORS:20130814-085742329
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Abstract
A class of titanium precatalysts of the type (ONO)TiX_2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe_2) has been synthesized and crystallographically characterized. The (ONO)TiX_2 (X = Bn, NMe_2, X_2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe_2, py; R = Ph, ^tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn_2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active Ti^(II) species that is generated in situ from 1. Depending on reaction conditions, these Ti^(II) species are proposed to be generated through Ti benzylidene or imido intermediates. A formally Ti^(II) complex, (ONO)Ti^(II)(η^2-C_2H_4)(HNMe_2) (7), has been prepared and structurally characterized.
Item Type: | Article | |||||||||
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Additional Information: | © 2013 American Chemical Society. Received: January 29, 2013; Published: June 3, 2013. We thank Lawrence Henling and Dr. Michael Day for assistance with the X-ray studies. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology (CHE- 0639094). This work has been supported by USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431) and by the KAUST Center-In-Development at King Fahd University of Petroleum and Minerals (Dhahran, Saudi Arabia). | |||||||||
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Issue or Number: | 12 | |||||||||
DOI: | 10.1021/om400080g | |||||||||
Record Number: | CaltechAUTHORS:20130814-085742329 | |||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20130814-085742329 | |||||||||
Official Citation: | Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II) Ian A. Tonks, Josef C. Meier, and John E. Bercaw Organometallics 2013 32 (12), 3451-3457 | |||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
ID Code: | 39908 | |||||||||
Collection: | CaltechAUTHORS | |||||||||
Deposited By: | Tony Diaz | |||||||||
Deposited On: | 16 Aug 2013 23:05 | |||||||||
Last Modified: | 09 Nov 2021 23:47 |
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