Visible‐Light‐Induced Dearomatizations

European Journal of Organic Chemistry, Journal Year: 2019, Volume and Issue: 2020(10), P. 1259 - 1273

Published: Sept. 26, 2019

The dearomatization of aromatic compounds is an important synthetic strategy used in accessing complex three‐dimensional structures from simple precursors. This minireview aims to provide overview recent advancements this area, with a specific focus on visible‐light‐mediated dearomative transformations. Compared the conventional high‐energy ultraviolet (UV) light‐promoted processes, not only these new approaches offer milder reaction conditions accommodate wider variety substrates sensitive functionalities, but also enable use photocatalysts and other promoters, significantly expanding space. Application transformations synthesis bioactive are discussed.

Language: Английский

---

Manganese‐Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by π–π Interaction**

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 60(10), P. 5108 - 5113

Published: Nov. 26, 2020

Abstract The non‐noble metal‐catalyzed asymmetric hydrogenation of N‐heteroaromatics, quinolines, is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the affording high yields and enantioselectivities (up to 97 % ee). turnover number 3840 was reached at a low loading (S/C=4000), which competitive with most effective noble metal catalysts for this reaction. precise regulation enantioselectivity were ensured by π–π interaction.

Language: Английский

---

A General Catalyst Based on Cobalt Core–Shell Nanoparticles for the Hydrogenation of N‐Heteroarenes Including Pyridines

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(40), P. 17408 - 17412

Published: June 16, 2020

Abstract Herein, we report the synthesis of specific silica‐supported Co/Co 3 O 4 core–shell based nanoparticles prepared by template cobalt‐pyromellitic acid on silica and subsequent pyrolysis. The optimal catalyst material allows for general selective hydrogenation pyridines, quinolines, other heteroarenes including acridine, phenanthroline, naphthyridine, quinoxaline, imidazo[1,2‐a]pyridine, indole under comparably mild reaction conditions. In addition, recycling these Co their ability dehydrogenation catalysis are showcased.

Language: Английский

---

Dearomative Photocatalytic Construction of Bridged 1,3‐Diazepanes

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(10), P. 4121 - 4130

Published: Jan. 8, 2020

Abstract The construction of diverse sp 3 ‐rich skeletal ring systems is importance to drug discovery programmes and natural product synthesis. Herein, we report the photocatalytic 2,7‐diazabicyclo[3.2.1]octanes (bridged 1,3‐diazepanes) via a reductive diversion Minisci reaction. fused tricyclic proposed form radical addition C4 position 4‐substituted quinoline substrates, with subsequent Hantzsch ester‐promoted reduction dihydropyridine intermediate which undergoes in situ two‐electron closure bridged diazepane architecture. A wide scope N‐arylimine derivatives was demonstrated good efficiency observed sterically congested all‐carbon quaternary centers. Computational experimental mechanistic studies provided insights into reaction mechanism regioselectivity/diastereoselectivity.

Language: Английский

---

Brønsted Acid Catalyzed Dearomatization by Intramolecular Hydroalkoxylation/Claisen Rearrangement: Diastereo‐ and Enantioselective Synthesis of Spirolactams

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(52), P. 27164 - 27170

Published: Oct. 21, 2021

Described herein is a novel Brønsted acid catalyzed intramolecular hydroalkoxylation/Claisen rearrangement, allowing the practical and atom-economic synthesis of range valuable spirolactams from readily available ynamides in generally good to excellent yields with diastereoselectivities broad substrate scope. Importantly, an unexpected dearomatization nonactivated arenes heteroaromatic compounds involved this tandem sequence. Moreover, asymmetric version cyclization was also achieved by efficient kinetic resolution chiral phosphoric catalysis. In addition, [3,3]-rearrangement shown be kinetically preferred over related [1,3]-rearrangement theoretical calculations.

Language: Английский

---

Chemoselective 1,2‐Reduction and Regiodivergent Deuteration of Chromium‐Bound Arenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(18)

Published: Feb. 23, 2023

Herein, a general strategy for chemo- and regioselective 1,2-reduction of chromium-bound arenes was developed, thus providing rapid access to 1,3-cyclohexadienes. Selective arene activation via π-complexation along with the use mild hydride Ph3 SiH can overcome inherently low reactivity π-bonds while tolerating various reduction-sensitive functional groups. Its versatility further enables regiodivergent deuteration. Using different sequences (non)deuterated acid reagents, deuterated positions as well degrees deuterium incorporation be controlled precisely, which leads large previously inaccessible chemical space 1,3-cyclohexadiene isotopologues. A reasonable mechanism proposed based on intermediate capture control experiments. The synthetic value this selective demonstrated in formal total synthesis (±)-galanthamine (±)-lycoramine.

Language: Английский

---

Enantio‐ and Diastereoselective, Complete Hydrogenation of Benzofurans by Cascade Catalysis

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(24), P. 13677 - 13681

Published: April 12, 2021

We report an enantio- and diastereoselective, complete hydrogenation of multiply substituted benzofurans in a one-pot cascade catalysis. The developed protocol facilitates the controlled installation up to six new defined stereocenters produces architecturally complex octahydrobenzofurans, prevalent many bioactive molecules. A unique match chiral homogeneous ruthenium-N-heterocyclic carbene situ activated rhodium catalyst from precursor act sequence enable presented process.

Language: Английский

---

Interrupted Pyridine Hydrogenation: Asymmetric Synthesis of δ‐Lactams

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(12), P. 6425 - 6429

Published: Jan. 18, 2021

Abstract Metal‐catalyzed hydrogenation is an effective method to transform readily available arenes into saturated motifs, however, current strategies are limited the formation of C−H and N−H bonds. The stepwise addition hydrogen yields reactive unsaturated intermediates that rapidly reduced. In contrast, interruption complete by further functionalization offers great potential for increasing chemical complexity in a single reaction step. Overcoming tenet full reduction arene has been seldom demonstrated. this work we report synthesis sought‐after, enantioenriched δ‐lactams from oxazolidinone‐substituted pyridines water interrupted mechanism.

Language: Английский

---

Accessing Difluoromethylated and Trifluoromethylated cis‐Cycloalkanes and Saturated Heterocycles: Preferential Hydrogen Addition to the Substitution Sites for Dearomatization

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(47), P. 16785 - 16789

Published: Sept. 13, 2019

Reported here is a straightforward process in which cyclic (alkyl)(amino)carbene/Rh catalyst system facilitates the preferential addition of hydrogen to substitution sites difluoromethylated and trifluoromethylated arenes heteroarenes, leading dearomative reduction. This strategy enables diastereoselective synthesis cis-difluoromethylated cis-trifluoromethylated cycloalkanes saturated heterocycles, even allows formation all-cis multi-trifluoromethylated products with defined equatorial orientation di- trifluoromethyl groups. Deuterium-labeling studies indicate that preferentially attacks planar arenes, resulting dearomatization, possibly heterogeneous Rh as reactive species, followed by either reversible or irreversible nonsubstitution sites.

Language: Английский

---

Acceptorless Dehydrogenative Coupling Reactions by Manganese Pincer Complexes

Asian Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 10(8), P. 1958 - 1985

Published: May 26, 2021

Abstract Acceptorless dehydrogenative coupling reactions has emerged as one of the promising technique in synthetic organic chemistry to construct carbon‐carbon and carbon‐heteroatom bonds an environmentally benign sustainable way. The methodology is highly atom economical produces water hydrogen byproducts. This protocol, coupled with earth‐abundant less toxic manganese catalyst provides a unique opportunity various synthons biologically important motifs. In recent years, tremendous progress been made catalysis based on pincer ligands for homogeneous transformations. review covers field catalyzed acceptorless reactions, their scope brief mechanistic discussion.

Language: Английский

---