Journal of the American Chemical Society
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Cp2Ti(III)Cl and Analogues as Sustainable Templates in Organic
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(16) Diéguez, H. R.; López, A.; Domingo, V.; Arteaga, J. F.;
Dobado, J. A.; Herrador, M. M.; Quílez del Moral, J. F.; Barrero, A.
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(17) Zheng, X.; Dai, X.-J.; Yuan, H.-Q.; Ye, C.-X.; Ma, J.; Huang,
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(18) Cp*TiCl3 has seldom been investigated in Ti catalysis. For
recent elegant work, see: Hao, W.; Wu, X.; Sun, J. Z.; Siu, J. C.;
MacMillan, S. N.; Lin, S. Radical Redox-Relay Catalysis: Formal
[3+2] Cycloaddition of N-Acylaziridines and Alkenes. J. Am. Chem.
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Deoxygenative Functionalization of Hydroxy Groups via
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(9) Lackner, G. L.; Quasdorf, K. W.; Overman, L. E. Direct
Construction of Quaternary Carbons from Tertiary Alcohols via
Photoredox-Catalyzed
Fragmentation
of tert-Alkyl N-
Phthalimidoyl Oxalates. J. Am. Chem. Soc. 2013, 135, 15342.
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D. W. C.; Overman, L. E. Oxalates as Activating Groups for
Alcohols in Visible Light Photoredox Catalysis: Formation of
Quaternary Centers by Redox-Neutral Fragment Coupling. J. Am.
Chem. Soc. 2015, 137, 11270. (b) Zhang, X.; MacMillan, D. W. C.
Alcohols as Latent Coupling Fragments for Metallaphotoredox
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(19) Trost, B. M.; Crawley, M. L. Asymmetric Transition-Metal-
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(11) (a) Ye, Y.; Chen, H.; Sessler, J. L.; Gong, H. Zn-Mediated
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(13) Ukaji and co-workers have recently reported an example of
stoichiometric radical alkylation of a benzylic tertiary alcohol
using TiCl4(collidine) (2.0 equiv). see: Suga, T.; Shimazu, S.; Ukaji,
Y. Low-Valent Titanium-Mediated Radical Conjugate Addition
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(14) (a) Yan, X. B.; Li, C. L.; Jin, W. J.; Guo, P.; Shu, X.-Z.
Reductive coupling of benzyl oxalates with highly functionalized
alkyl bromides by nickel catalysis. Chem. Sci. 2018, 9, 4529. (b)
Duan, J.; Du, Y.-F.; Pang, X.; Shu, X.-Z. Ni-catalyzed cross-
electrophile coupling between vinyl/aryl and alkyl sulfonates:
synthesis of cycloalkenes and modification of peptides. Chem.
Sci. 2019, 10, 8706. (c) Jia, X. G.; Guo, P.; Duan, J.; Shu, X.-Z. Dual
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(20)Rozen, S.; Hagooly, A.; Harduf, R. Synthesis of r-
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(21) (a) Metal-Catalyzed Cross-coupling Reactions; Diederich,
F., Stang, P. G., Eds.; Wiley-VCH: New York, 1998. (b) Ref 3.
(22) Modern Alkyne Chemistry. Catalytic and Atom-Economic
Transformations, Trost, B.M. and Li, C.-J., Eds., Weinheim: Wiley,
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(23) The structures of the bis-alkylated products (3bk-1 from
1al, 3bl-1 from 1am, 3bt-1 from 1au) can be found in the
Supporting Information (pages S56, S57, and S61).
(24) (a) Liwosz, T. W.; Chemler, S. R. Copper-Catalyzed
Oxidative Heck Reactions between Alkyltrifluoroborates and
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(15) For selected recent reviews, see: (a) Morcillo, S. P.; Miguel,
D.; Campaña, A. G.; Á lvarez de Cienfuegos, L.; Justicia, J.; Cuerva,
J. M. Recent applications of Cp2TiCl in natural product synthesis.
Org. Chem. Front. 2014, 1, 15. (b) Streuff, J.; Gansäuer, A. Metal-
Catalyzed b-Functionalization of Michael Acceptors through
Reductive Radical Addition Reactions. Angew. Chem. Int. Ed. 2015,
54, 14232. (c) Castro Rodríguez, M.; Rodríguez García, I.;
Rodríguez Maecker, R. N.; Pozo Morales, L.; Oltra, J. E.; Rosales
Martínez, A. Cp2TiCl: An Ideal Reagent for Green Chemistry? Org.
Process Res. Dev. 2017, 21, 911. (d) Botubol-Ares, J. M.; Durán-Peña,
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