A selective reductive amination of aldehydes by the use of Hantzsch dihydropyridines as reductant

Itoh, Takashi; Nagata, Kazuhiro; Miyazaki, Michiko; Ishikawa, Hiroyuki; Kurihara, Ayako; Ohsawa, Akio

doi:10.1016/j.tet.2004.05.096

Cited by 92 publications

(52 citation statements)

References 29 publications

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“…The crude product was purified by column chromatography. The obtained analytical data are in agreement with literature reports [26,54,[69][70][71][72][73][74][75][76][77][78][79][80]. …”

Section: Discussionsupporting

confidence: 91%

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Enthaler

2010

Catal Lett

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In the present study, the zinc-catalyzed reductive amination of various aldehydes has been examined in detail. Simple zinc(II) triflate was applied as hydrosilylation catalyst for the reduction of the in situ formed imine by condensation of an aldehyde with an amine. Using a practical Lewis acid catalyst and PMHS [poly(methylhydrosiloxane)] as cheap hydride source excellent yields and a broad functional group tolerance were achieved.

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“…The crude product was purified by column chromatography. The obtained analytical data are in agreement with literature reports [26,54,[69][70][71][72][73][74][75][76][77][78][79][80]. …”

Section: Discussionsupporting

confidence: 91%

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Enthaler

2010

Catal Lett

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“…[11] In pioneering studies, the research groups of Akiyama [10] and Terada [11] recently introduced relatively strong chiral phosphoric acid catalysts for asymmetric addition reactions to aldimines as a new strategy for organic catalysis. [12,13] Inspired by these studies, and the recent observation that imines are reduced with Hantzsch esters in the presence of achiral Lewis or Brønsted acid catalysts, [14] we envisioned a catalytic cycle which is initiated by protonation of ketimine 1 from a chiral Brønsted acid catalyst 2 [Eq. (2)].…”

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confidence: 99%

A Powerful Brønsted Acid Catalyst for the Organocatalytic Asymmetric Transfer Hydrogenation of Imines

2005

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The catalytic hydrogenation of alkenes, ketones, and imines is arguably one of the most important transformations in chemistry. Powerful asymmetric versions have been realized that require metal catalysts or the use of a stoichiometric amount of metal hydrides [Eq. (1)]. [1] Although effective and industrially relevant catalytic asymmetric hydrogenations and transfer hydrogenations of olefins and ketones have been developed, the corresponding imine reductions, although potentially highly useful for the synthesis of enantiomerically pure amines, are less advanced.[2] Living organisms employ organic dihydropyridine cofactors such as nicotinamide adenine dinucleotide (NADH) in combination with enzyme catalysts for the reduction of imines.[3] Chemical transition metal catalyzed asymmetric imine reductions have also been developed, [4] and are used, in at least one case, on an industrial scale. [5] However, with the exception of interesting Lewis base catalyzed asymmetric imine hydrosilylations, [6] organocatalytic and metal-free variants were not known. Recently, we and MacMillan and co-workers developed an asymmetric transfer hydrogenation of a,b-unsaturated aldehydes catalyzed by a chiral ammonium salt by using Hantzsch esters as a biomimetic hydrogen source. [7] Rueping et al. [8] very recently reported the development of a novel and elegant approach using Hantzsch esters as the reducing reagent for the catalytic asymmetric reduction of imines using a chiral Brønsted acid catalyst previously developed by Akiyama et al.

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“…Primary alkyl halides, such as methyl iodide, n-pentyl bromide, even long chain dodecyl bromide, gave rise to the alkoxyanilines in satisfactory yields ( We also prepare the N-alkylated derivatives of aminophenols selectively via the condensation of aminophenols and an aldehyde and subsequent reduction with sodium borohydride in a one-pot reaction (Scheme 2). [13][14][15] The excellent overall yields were achieved for all given examples. The results are listed in Table 2.…”

Section: Resultsmentioning

confidence: 69%

Selective alkylation of aminophenols

Xu¹,

Wang²

2010

Arkivoc

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A selective reductive amination of aldehydes by the use of Hantzsch dihydropyridines as reductant

Cited by 92 publications

References 29 publications

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

Practical One-Pot Synthesis of Secondary Amines by Zinc-Catalyzed Reductive Amination

A Powerful Brønsted Acid Catalyst for the Organocatalytic Asymmetric Transfer Hydrogenation of Imines

Selective alkylation of aminophenols

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