Chemical Science, Год журнала: 2021, Номер 12(17), С. 6064 - 6072
Опубликована: Янв. 1, 2021
The activation of both aromatic and aliphatic ureas as N-centered nucleophiles in intramolecular Michael addition reactions to α,β-unsaturated esters was achieved under bifunctional iminophosphorane squaramide superbase catalysis.
Язык: Английский
Chemistry - A European Journal, Год журнала: 2021, Номер 27(42), С. 10807 - 10825
Опубликована: Май 25, 2021
The renaissance of Brønsted superbases is primarily based on their pronounced capacity for a large variety chemical transformations under mild reaction conditions. Four major set screws are available the selective tuning basicity: nature basic center (N, P, …), degree electron donation by substituents to central atom, possibility charge delocalization, and energy gain hydrogen bonding. Within past decades, plethora neutral electron-rich phosphine phosphazene bases have appeared in literature. Their outstanding properties advantages over inorganic or charged now made them indispensable as auxiliary deprotonation processes. Herein, an update chemistry phosphines phosphazenes given. In addition, due widespread interest, use catalysis ligands coordination highlighted.
Язык: Английский
Процитировано
44
Science, Год журнала: 2022, Номер 376(6598), С. 1224 - 1230
Опубликована: Июнь 9, 2022
Synthetic methods that enable simultaneous control over multiple stereogenic centers are desirable for the efficient preparation of pharmaceutical compounds. Herein, we report discovery and development a catalyst-mediated asymmetric Michael addition/crystallization–induced diastereomer transformation broad scope. The sequence controls three centers, two which stereochemically labile. configurational instability 1,3-dicarbonyls nitroalkanes, typically considered liability in stereoselective synthesis, is productively leveraged by merging enantioselective Brønsted base organocatalysis thermodynamic stereocontrol using single convergent crystallization. synthesis useful γ-nitro β-keto amides containing contiguous thus achieved from acceptors prochiral centers.
Язык: Английский
Процитировано
37
Journal of the American Chemical Society, Год журнала: 2022, Номер 144(2), С. 1006 - 1015
Опубликована: Янв. 6, 2022
The first metal-free catalytic intermolecular enantioselective Michael addition to unactivated α,β-unsaturated amides is described. Consistently high enantiomeric excesses and yields were obtained over a wide range of alkyl thiol pronucleophiles electrophiles under mild reaction conditions, enabled by novel squaramide-based bifunctional iminophosphorane catalyst. Low catalyst loadings (2.0 mol %) achieved on decagram scale, demonstrating the scalability reaction. Computational analysis revealed origin enantiofacial selectivity via relevant transition structures provided substantial support for specific noncovalent activation carbonyl group amide
Язык: Английский
Процитировано
36
Journal of the American Chemical Society, Год журнала: 2023, Номер 145(15), С. 8593 - 8599
Опубликована: Апрель 11, 2023
Challenges for the development of efficacious new superbases include their ease synthesis, chemical stability, and high basicity, while minimizing nucleophilicity is important reducing unwanted side reactions. Here, we introduce a family organic superbases, compact amine-crown ether rotaxanes, which show desirable characteristics in all these respects. Metal-free active template synthesis provides access to range rotaxanes with as little three atoms between stoppering groups, locking location small crown (21C7 24C8 derivatives) over amine group axle. The forced proximity interlocked protophilic components results pKaH+ values 32.2 acetonitrile, up 13 units greater than non-interlocked components, brings free base into basicity realm phosphazene superbases. rotaxane are generally chemically stable and, model reaction eliminate HBr from primary alkyl bromide complete selectivity deprotonation alkylation. Their modest size, low nucleophilicity, best cases, rapid substrate kinetics excellent hydrolytic stability make intriguing candidates potential applications supramolecular materials chemistry.
Язык: Английский
Процитировано
22
Asian Journal of Organic Chemistry, Год журнала: 2023, Номер 12(3)
Опубликована: Янв. 30, 2023
Abstract The [1,2]‐phospha‐Brook rearrangement involves the migration of dialkoxyphosphoryl moiety alkoxide an α‐hydroxyphosphonate from carbon to oxygen generate α‐oxygenated carbanion. that is precursor for easily accessible by deprotonation α‐hydroxyphosphonates or addition anion secondary phosphites carbonyl compounds under influence a Brønsted base. This review article summarized recent development base‐catalyzed reactions in which utilized generation carbon‐based anionic nucleophiles.
Язык: Английский
Процитировано
19
Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(21)
Опубликована: Март 16, 2023
Abstract Herein we describe the enantioselective intermolecular conjugate addition of nitroalkanes to unactivated α,β‐unsaturated esters, catalyzed by a bifunctional iminophosphorane (BIMP) superbase. The transformation provides most direct access pharmaceutically relevant enantioenriched γ‐nitroesters, utilizing feedstock chemicals, with unprecedented selectivity. methodology exhibits broad substrate scope, including β‐(fluoro)alkyl, aryl and heteroaryl substituted electrophiles, was successfully applied on gram scale reduced catalyst loading, and, additionally, recovery carried out. formal synthesis range drug molecules, an ( S )‐rolipram were achieved. Additionally, computational studies revealed key reaction intermediates transition state structures, provided rationale for high enantioselectivities, in good agreement experimental results.
Язык: Английский
Процитировано
19
Chemical Science, Год журнала: 2024, Номер 15(16), С. 5980 - 5992
Опубликована: Янв. 1, 2024
N -Cyano iminophosphoranes are synthesized using electrochemistry and evaluated as ligands in various nickel-catalysed reactions. The electronic structural properties of these were studied both computationally experimentally.
Язык: Английский
Процитировано
7
ACS Catalysis, Год журнала: 2021, Номер 11(10), С. 6316 - 6324
Опубликована: Май 11, 2021
Chiral N-heterocyclic carbenes (NHCs) have been recently established as powerful catalysts for enantioselective bond-forming processes via noncovalent interactions. The underlying HOMO-raising activation of nucleophiles takes advantage the strong Brønsted basicity NHCs. However, scope compatible electrophiles has quite limited. In this article, we report a bifunctional NHC with an embedded hydrogen-bonding motif that shows remarkable tolerance various Michael acceptors in asymmetric aza-conjugate addition reaction. catalytic efficiency far exceeds benchmark tertiary amine-thiourea scaffold.
Язык: Английский
Процитировано
39
Chemical Science, Год журнала: 2022, Номер 13(46), С. 13782 - 13794
Опубликована: Янв. 1, 2022
A database of thousands experimentally-derived or combinatorially enriched organocatalysts and fragments to navigate chemical space optimize reaction properties.
Язык: Английский
Процитировано
27
European Journal of Organic Chemistry, Год журнала: 2022, Номер 26(7)
Опубликована: Дек. 15, 2022
Abstract Thiourea‐ and squaramide‐based bifunctional base catalysts represent nowadays a powerful tool in the field of asymmetric catalysis have demonstrated very efficient for promoting wide variety transformations enantioselectively. New versions that incorporate one or various additional H‐bond donor site(s) catalyst structure been developed recently which led to more active (reduced loadings) selective catalysts. This review highlights pioneering ideas most recent contributions area with material organized according nature functionality. The advantages, current limitations perspectives these new multifunctional are discussed.
Язык: Английский
Процитировано
25