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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)

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
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/om400080gDOIArticle
http://pubs.acs.org/doi/abs/10.1021/om400080gPublisherArticle
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).
Funders:
Funding AgencyGrant Number
NSF CRIF:MU AwardCHE-0639094
Department of Energy (DOE) Office of Basic Energy SciencesDE-FG03-85ER13431
King Fahd University of Petroleum and Minerals (KFUPM) KAUST Center-In-DevelopmentUNSPECIFIED
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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