Reductive dimerization of imines in a Pb/Al bimetal redox system

Tanaka, Hideo; Dhimane, Hamid; Fujita, Hiroyuki; Ikemoto, Youichi; Torii, Sigeru

doi:10.1016/s0040-4039(00)82121-8

Cited by 64 publications

(12 citation statements)

References 13 publications

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“…The coupling reaction using indium proceeds only under drastic conditions. In addition, bimetal redox systems such as Pb/Al are reported to mediate such reactions 7. Lanthanides, such as Sm and Yb, are widely used for the reductive coupling of both carbonyl compounds and imines 8…”

Section: Introductionmentioning

confidence: 99%

Diastereospecific Coupling of Imines by Low‐Valent Titanium: An Experimental and Computational Study

Kumar¹,

Samuelson²

2010

Eur J Org Chem

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The reaction of phenylsilane (PhSiH3) and titanium(IV) isopropoxide [Ti(OiPr)4] generates low‐valent titanium alkoxides that reduce and reductively couple imines. The C–C coupling reaction is diastereospecific, with exclusive formation of the (±)‐isomer. The yield is dependent on the concentration of titanium(IV) isopropoxide used. Using imines with varying electronic demand revealed that the coupling is most efficient for unsubstituted imines. The involvement of a trimeric titanium biradical species is invoked to explain the observed concentration dependence and diastereospecificity in the reaction. Multilayer ONIOM (“our own n‐layered integrated molecular orbital and molecular mechanics”) calculations were carried out on the plausible intermediates involved by using the Guassian 09 suite of programs. Formation of the trimeric biradical species leading to the formation of the (±)‐isomer is more favored than formation of the trimeric biradical species, which leads to the meso‐isomer. Similar calculations with dimeric intermediates do not predict the (±)‐selectivity. Mass spectral analysis of the reaction mixture indicates the presence of a trimeric titanium alkoxide species.

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Section: Introductionmentioning

confidence: 99%

Diastereospecific Coupling of Imines by Low‐Valent Titanium: An Experimental and Computational Study

Kumar¹,

Samuelson²

2010

Eur J Org Chem

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“…It should be underlined that attempted resolution of d , l ‐ 3b , obtained by reductive dimerization of N ‐ ortho ‐(methoxybenzylidene)benzylamine11 with zinc/methanesulfonic acid and chromatographic separation of the meso diastereomer, failed using both 1 and 2 equivalents of tartaric acid. Analogously, we did not find suitable conditions for the separation of the enantiomers of 4b,c by HPLC analysis on a chiral column.…”

Section: Resultsmentioning

confidence: 99%

New Chiral 1,2‐Diamines and Their Use in Zinc‐Catalyzed Asymmetric Hydrosilylation of Acetophenone

et al. 2004

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“…PbBr 2 /Al system is effective for the coupling of aromatic imines in the presence of trifluoroacetic acid or AlBr 3 . 22 No reductive coupling of aliphatic imines and ketimines occurs with this catalytic system. PbCl 2 or Sn(II) salt is also used as a catalyst.…”

Section: Scheme 10mentioning

confidence: 94%

A Catalytic System for Reductive Transformations via One-Electron Transfer

Hirao

1999

Synlett

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Recent advances in the catalytic one-electron reduction are the subject of this account. A titanium-, vanadium-or chromium-catalyzed reduction reaction including dehalogenation, pinacol coupling, the McMurry coupling, the related radical cyclization, and the Nozaki-Hiyama-Kishi reaction has been developed by constructing a multi-component system in combination with a co-reductant and additives, which serve for the liberation of the catalyst and the facilitation of the recycling steps. The high stereoselectivity is allowed to be attained in some catalytic reductive bond formations.

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Reductive dimerization of imines in a Pb/Al bimetal redox system

Cited by 64 publications

References 13 publications

Diastereospecific Coupling of Imines by Low‐Valent Titanium: An Experimental and Computational Study

Diastereospecific Coupling of Imines by Low‐Valent Titanium: An Experimental and Computational Study

New Chiral 1,2‐Diamines and Their Use in Zinc‐Catalyzed Asymmetric Hydrosilylation of Acetophenone

A Catalytic System for Reductive Transformations via One-Electron Transfer

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