Rapid and Mild Metal-Free Reduction of Epoxides to Primary Alcohols Mediated by HFIP

ACS Catalysis, Год журнала: 2022, Номер 12(6), С. 3309 - 3316

Опубликована: Фев. 25, 2022

The reduction of epoxides is a powerful tool to access anti-Markovnikov alcohols, but reported methods are poorly compatible with strongly electronically deactivated substrates. Here, we describe general method for the linear-selective styryl oxides incorporating strong electron-withdrawing groups. remains more traditional epoxide motifs, such as aliphatic and electron-rich styrene oxides. Other (hetero)cycles oxetanes, tetrahydrofurans, aziridines, cyclopropanes can also be reductively opened. This user-friendly reaction relies on combination Brønsted acid catalyst hexafluoroisopropanol solvent, thus, in contrast existing methods, it does not require anhydrous reagents or an inert atmosphere. generated primary alcohols conveniently functionalized situ by dehydrative Friedel–Crafts arylation without preactivation.

Язык: Английский

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Mechanochemical Cascade Cyclization of Cyclopropyl Ketones with 1,2-Diamino Arenes for the Direct Synthesis of 1,2-Disubstituted Benzimidazoles

The Journal of Organic Chemistry, Год журнала: 2024, Номер 89(13), С. 9427 - 9439

Опубликована: Июнь 21, 2024

A mechanochemical synthesis of 1,2-disubstituted benzimidazoles from donor-acceptor cyclopropyl ketones and 1,2-diaminoarenes under metal-free solventless conditions is reported. The reaction does not require inert promoted by a stoichiometric amount 1,1,1,3,3,3-hexafluoroisopropanol. This cascade involves ring-opening, cyclization, retro-Mannich with aryl 1,2-diamines. Compared to its solution-phase counterpart, this approach shows fast reactivity (24 vs 1.5 h). Mechanistic investigations electrospray ionization mass spectrometry helped us propose the mechanism.

Язык: Английский

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Hexafluoroisopropanol‐Promoted Haloamidation and Halolactonization of Unactivated Alkenes

Angewandte Chemie International Edition, Год журнала: 2020, Номер 60(2), С. 946 - 953

Опубликована: Сен. 21, 2020

Pyrrolidine and piperidine derivatives bearing halide functional groups are prevalent building blocks in drug discovery as halides can serve an anchor for post-modifications. In principle, one of the simplest ways to build these frameworks is haloamination alkenes. While progress has been made this field, notably with development enantioselective versions, reaction still fraught limitations terms reactivity. Besides, a major question remaining understand mechanism at work. The formation haliranium intermediate typically mentioned, but limited mechanistic evidence supports it. Reported here efficient metal- oxidant-free protocol achieve haloamidation olefins, promoted by hexafluoroisopropanol, along DFT investigation mechanism. These findings should guide future more complex transformations field halofunctionalization.

Язык: Английский

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Hexafluoroisopropanol-Enabled Copper-Catalyzed Asymmetric Halogenation of Cyclic Diaryliodoniums for the Synthesis of Axially Chiral 2,2′-Dihalobiaryls

Organic Letters, Год журнала: 2020, Номер 23(2), С. 329 - 333

Опубликована: Дек. 29, 2020

An efficient asymmetric halogenation of cyclic diaryliodonium salts is demonstrated, which gives access to a wide range axially chiral 2,2′-dihalobiaryls in good excellent yields and with enantioselectivities. The use CuX bisoxazoline ligand tetrabutylammonium halides the unique solvent hexafluoroisopropanol (HFIP) led best results process. can be transformed into number enantiopure ligands that could potentially useful catalysis.

Язык: Английский

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Asymmetric synthesis of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates

Chemical Science, Год журнала: 2021, Номер 12(33), С. 11181 - 11190

Опубликована: Янв. 1, 2021

This study describes general methods for the enantioselective syntheses of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates through dirhodium tetracarboxylate-catalysed asymmetric cyclopropanation vinyl heterocycles with aryl- or heteroaryldiazoacetates. The reactions are highly diastereoselective high induction could be achieved using either (R)-pantolactone as a chiral auxiliary tetracarboxylate catalysts. For meta- para-substituted heteroaryldiazoacetates optimum catalyst was Rh2(R-p-Ph-TPCP)4. In case ortho-substituted heteroaryldiazoacetates, Rh2(R-TPPTTL)4. reaction substrates, 2-chloropyridine required an additive in presence 4 Å molecular sieves 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). Under optimized conditions, conducted variety heterocycles, such pyridines, pyrazines, quinolines, indoles, oxadiazoles, thiophenes pyrazoles.

Язык: Английский

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