Nickel Metallaphotoredox Buchwald–Hartwig Amination Reactions: A Perspective on Irradiation Light Wavelength

European Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 27(2)

Published: Oct. 27, 2023

Abstract The construction of C−N bonds is considered one the most useful reactions in synthetic chemistry due to their widespread presence pharmaceuticals, natural products, etc. Pd‐catalyzed Buchwald–Hartwig amination (BHA) has provided efficient method form (hetero)aryl amines but it required strong base and sophisticated ligands. In comparison, combination photocatalysis nickel revolutionized catalytic strategies emerging as a quintessence realize BHA, termed Ni‐metallaphotoredox BHA. To pursue universal protocol, diverse photocatalysts were designed employed smoothly promoted bond formations under irradiation light from ultraviolet red light, respectively. Note that matching photocatalyst was critical for success. Therefore, this review mainly focuses on discussion BHA according light's wavelength, covering ultraviolet, purple, blue, red, white well solar light. We try find clue relationship structure‐photophysical behaviors same or different At last, current limitations potential trends advancing are highlighted. deem could encourage chemists continue designing suitable sunlight mimicking plants’ photosynthesis.

Language: Английский

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Photoinduced Reductive C–C and C–Heteroatom Couplings from Bis-cyclometalated Pt(IV) Alkynyl Complexes

Inorganic Chemistry, Journal Year: 2023, Volume and Issue: 62(35), P. 14411 - 14421

Published: Aug. 24, 2023

Unsymmetrical dicarboxylato complexes [Pt(tpy)2(O2CR)2] [tpy = cyclometalated 2-(p-tolyl)pyridine, R Me, CF3] react with the terminal alkynes 4-methoxyphenylacetylene, phenylacetylene, 4-(trifluoromethyl)phenylacetylene or 3,5-difluorophenylacetylene in presence of a base to produce mer-[Pt(tpy)2(O2CR)(CCAr)], which metalated carbon atoms are meridional arrangement. Irradiation trifluoroacetato derivatives 365 nm LED source leads isomerization facial complexes, can be converted chlorido upon reaction NH4Cl. In contrast, irradiation acetato four different processes, namely, reduction cis-[Pt(tpy)2], annulations involving one tpy ligands and Cα Cβ alkynyl give benzoquinolizinium derivatives, geometry, C-O couplings between ligand tpy. The first two processes favored by electron-donating groups on alkynyl, whereas electron-withdrawing favor last two. fac-[Pt(tpy)2(O2CCF3)(CCAr)] medium-pressure Hg UV lamp reductive C-C coupling atom pyridoisoindolium except for methoxyphenylacetylide derivative, is photostable. On basis TDDFT calculations, photoreactivity mer attributed 3LLCT [π(alkynyl) → π*(tpy)] excited states 3LMCT dσ*] rest accessible through thermal population from 3LC(tpy) states. fac photoreactive pentacoordinate intermediates.

Language: Английский

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Photogenerated Ni(I)–Bipyridine Halide Complexes: Structure-Function Relationships for Competitive C(sp2)–Cl Oxidative Addition and Dimerization Reactivity Pathways

Published: March 21, 2023

We report the facile photochemical generation of a library Ni(I)–bpy halide complexes (Ni(I)(Rbpy)X (R = t-Bu, H, MeOOC; X Cl, Br, I) and benchmark their relative reactivity toward competitive oxidative addition off-cycle dimerization pathways. Structure-function relationships between ligand set are developed, with particular emphasis on rationalizing previously uncharacterized ligand-controlled high energy challenging C(sp2)–Cl bonds. Through dual Hammett computational analysis, mechanism formal is found to proceed through an SNAr-type pathway, consisting nucleophilic two-electron transfer Ni(I) 3d(z2) orbital Caryl–Cl σ* orbital, which contrasts observed for activation weaker C(sp2)–Br/I The bpy substituent provides strong influence reactivity, ultimately determining whether or even occur. Here we elucidate origin this as arising from perturbations effective nuclear charge (Zeff) center. Electron donation metal decreases Zeff, leads significant destabilization entire 3d manifold. Decreasing electron binding energies powerful donor activate These changes also prove have analogous effect dimerization, in Zeff leading more rapid dimerization. Ligand-induced modulation thus tunable target by can be altered, providing direct route stimulate stronger C–X bonds potentially unveiling new ways accomplish Ni-mediated photocatalytic cycles.

Language: Английский

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2‐Hydroxypyridines as N‐ and O‐Nucleophiles in Organic Synthesis

European Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 27(2)

Published: Nov. 6, 2023

Abstract 2‐Hydroxypyridines have emerged as versatile nucleophiles in organic synthesis. The N ‐ and O ‐functionalization of 2‐hydroxypyridines affords straightforward practical methods for the construction ‐substituted 2‐pyridones 2‐hydroxypyridines, which are important structural motifs numerous natural products, pharmaceuticals biologically active compounds. Nonetheless, competition between presents an inevitable formidable challenge. In past few decades, chemoselective and/or has received extensive attention from synthetic community, resulting development elegant effective strategies to address this chemoselectivity. This review provides a summary recent advancements realm transition‐metal organo‐catalyzed, well visible‐light promoted functionalization including ‐alkylation, ‐allylation, ‐arylation, ‐alkenylation, ‐alkenylation.

Language: Английский

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Light-promoted, nickel-catalyzed C–N coupling of (hetero)aryl halides with benzophenone hydrazone for the synthesis of nitrogen-containing heterocycles

Organic Chemistry Frontiers, Journal Year: 2024, Volume and Issue: 11(21), P. 6089 - 6095

Published: Jan. 1, 2024

A highly effective method for synthesizing N -arylhydrazones by means of light-promoted C–N coupling (hetero)aryl halides with benzophenone hydrazone catalysis a Ni( ii )–aryl halide complex was reported.

Language: Английский

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