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Journal ArticleDOI: 10.1021/ACSCATAL.1C00153

Dual Palladium/Photoredox-Catalyzed Enantioselective and Regioselective Decarboxylative Hydroaminoalkylation of Allenes

02 Mar 2021-ACS Catalysis (American Chemical Society (ACS))-Vol. 11, Iss: 6, pp 3343-3350
Abstract: A dual palladium/photoredox-catalyzed regio- and enantioselective decarboxylative hydroaminoalkylation of allenes with amino acids is reported. This mild, redox-neutral, and atom-economic process a...

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Topics: Allene (52%)
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7 results found


Open access
01 Jan 2016-
Abstract: The first highly enantioselective catalytic protocol for the reductive coupling of ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by a chiral phosphoric acid catalyst and the photoredox catalyst Ir(ppy)2(dtbpy)PF6. Remarkably, these neutral ketyl radicals appear to remain H-bonded to the chiral conjugate base of the Brønsted acid during the course of a subsequent C-C bond-forming step, furnishing syn 1,2-amino alcohol derivatives with excellent levels of diastereo- and enantioselectivity. This work provides the first demonstration of the feasibility and potential benefits of concerted PCET activation in asymmetric catalysis.

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242 Citations


Journal ArticleDOI: 10.1002/ANIE.202107990
Dong-Jin Jang1, Sukhyun Lee1, Juyeol Lee1, Dohyun Moon  +1 moreInstitutions (1)
04 Oct 2021-Angewandte Chemie
Abstract: The Pd-catalyzed asymmetric addition reaction of β-keto acids to heteroatom-substituted allene is reported. This reaction generates β-substituted ketones in an asymmetric manner through a branch-selective decarboxylative allylation pathway. The reaction accommodates various alkoxyallenes as well as amidoallenes.

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Topics: Addition reaction (59%), Decarboxylation (57%), Allene (57%) ... show more

1 Citations


Journal ArticleDOI: 10.1021/JACS.1C06271
Hong-Hao Zhang1, Menghan Tang1, Jia-Jia Zhao1, Changhua Song1  +1 moreInstitutions (1)
Abstract: Transition-metal-catalyzed reductive coupling reactions have emerged as powerful protocols to construct C-C bonds. However, the development of enantioselective C(sp3)-C(sp3) reductive coupling remains challenging. Herein, we report a highly regio-, diastereo-, and enantioselective reductive homocoupling of allylic acetates through cooperative palladium and photoredox catalysis using diisopropylethylamine or Hantzsch ester as a homogeneous organic reductant. This straightforward protocol enables the stereoselective construction of C(sp3)-C(sp3) bonds under mild reaction conditions. A series of C2-symmetrical chiral 1,5-dienes were easily prepared with excellent enantioselectivities (up to >99% ee), diastereoselectivities (up to >95:5 dr), and regioselectivities (up to >95:5 rr). The resultant chiral 1,5-dienes can be directly used as chiral ligands in asymmetric synthesis, and they can be also transformed into other valuable chiral ligands.

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Topics: Photoredox catalysis (57%), Enantioselective synthesis (57%), Coupling reaction (55%) ... show more

1 Citations


Journal ArticleDOI: 10.1002/CHEM.202101890
Abstract: The use of allenes and 1,3-dienes as chiral allylmetal pronucleophiles in intermolecular catalytic enantioselective reductive additions to aldehydes, ketones, imines, carbon dioxide and other C=X electrophiles is exhaustively catalogued together with redox-neutral hydrogen auto-transfer processes. Coverage is limited to processes that result in both C-H and C-C bond formation. The use of alkynes as latent allylmetal pronucleophiles and multicomponent C=X allylations involving allenes and dienes is not covered. As illustrated in this review, the ability of allenes and 1,3-dienes to serve as tractable non-metallic pronucleophiles has evoked many useful transformations that have no counterpart in traditional allylmetal chemistry.

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1 Citations


Journal ArticleDOI: 10.1039/D1QO00955A
Jitender Singh1, Anoop Sharma1, Anuj Sharma1Institutions (1)
Abstract: Allenes are attractive molecules which serve as versatile synthons for several bioactive compounds and naturally occurring products. In the past few decades, the functionalization of allenes has caught tremendous attention, and several strategies have been developed for the functionalization of allenes. The past decade has witnessed the emergence of visible light mediated photoredox catalysis as a powerful manifold, which has in turn, significantly contributed to the functionalization of allenes via SET- or EnT processes. In this review, the visible light mediated functionalization of allenes has been summarized by compiling the literature of the last 12 years and their reaction mechanisms have been intensively discussed.

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Topics: Photoredox catalysis (52%)

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46 results found


Open accessJournal ArticleDOI: 10.1021/CR300503R
10 Jul 2013-Chemical Reviews
Abstract: A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron-transfer (SET) processes with organic substrates upon photoexcitation with visible light. Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) ruthenium(II), or Ru(bpy)32+ (Figure 1). These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long-lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+) that it may engage in bimolecular electron-transfer reactions in competition with deactivation pathways.3 Although these species are poor single-electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single-electron-transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox-active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes. Open in a separate window Figure 1 Ruthenium polypyridyl complexes: versatile visible light photocatalysts.

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Topics: Photoredox catalysis (62%), Ruthenium (54%), Visible spectrum (51%) ... show more

4,920 Citations


Journal ArticleDOI: 10.1126/SCIENCE.1962206
Barry M. Trost1Institutions (1)
06 Dec 1991-Science
Abstract: Efficient synthetic methods required to assemble complex molecular arrays include reactions that are both selective (chemo-, regio-, diastereo-, and enantio-) and economical in atom count (maximum number of atoms of reactants appearing in the products). Methods that involve simply combining two or more building blocks with any other reactant needed only catalytically constitute the highest degree of atom economy. Transition metal-catalyzed methods that are both selective and economical for formation of cyclic structures, of great interest for biological purposes, represent an important starting point for this long-term goal. The limited availability of raw materials, combined with environmental concerns, require the highlighting of these goals.

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Topics: Atom economy (52%)

3,528 Citations


Journal ArticleDOI: 10.1039/B913880N
Abstract: The use of visible light sensitization as a means to initiate organic reactions is attractive due to the lack of visible light absorbance by organic compounds, reducing side reactions often associated with photochemical reactions conducted with high energy UV light. This tutorial review provides a historical overview of visible light photoredox catalysis in organic synthesis along with recent examples which underscore its vast potential to initiate organic transformations.

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2,645 Citations


Journal ArticleDOI: 10.1021/ACS.CHEMREV.6B00057
Nathan A. Romero1, David A. Nicewicz1Institutions (1)
10 Jun 2016-Chemical Reviews
Abstract: In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

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Topics: Photoredox catalysis (61%)

2,478 Citations


Open accessJournal ArticleDOI: 10.1021/ACS.CHEMREV.6B00018
25 Apr 2016-Chemical Reviews
Abstract: The interaction between an electronically excited photocatalyst and an organic molecule can result in the genertion of a diverse array of reactive intermediates that can be manipulated in a variety of ways to result in synthetically useful bond constructions. This Review summarizes dual-catalyst strategies that have been applied to synthetic photochemistry. Mechanistically distinct modes of photocatalysis are discussed, including photoinduced electron transfer, hydrogen atom transfer, and energy transfer. We focus upon the cooperative interactions of photocatalysts with redox mediators, Lewis and Bronsted acids, organocatalysts, enzymes, and transition metal complexes.

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1,299 Citations