Subtopic Deep Dive
C-H Oxidative Cross-Coupling
Research Guide
What is C-H Oxidative Cross-Coupling?
C-H oxidative cross-coupling forms C-C bonds by direct dehydrogenative coupling of two C-H bonds using oxidants and catalysts, avoiding organometallic reagents.
This method enables selective arylation, alkylation, and cyclization reactions between arenes, alkenes, alkynes, and amines. Key examples include silver-mediated pyrrole synthesis (Ke et al., 2013, 103 citations) and enantioselective arylglycine formation (Wei et al., 2014, 85 citations). Over 10 papers from 2012-2023 document catalysts like Cu, Pd, Ag, and Sc with air or photoredox oxidants.
Why It Matters
C-H oxidative cross-coupling streamlines pharmaceutical synthesis by coupling abundant feedstocks like arylglycine esters and boronic acids, reducing steps and waste (Wei et al., 2014). It builds complex heterocycles like pyrroles from terminal alkynes and enamino esters for agrochemicals (Ke et al., 2013). Scalable Cu/air-mediated couplings of imidazoheterocycles with glycine esters support industrial amino acid derivative production (Jiao et al., 2017).
Key Research Challenges
Selectivity in C-H activation
Distinguishing multiple C-H sites in complex molecules leads to over-oxidation or side products. Wei et al. (2014) achieved enantioselectivity with chiral ligands, but broad substrate scope remains limited. Ke et al. (2013) used silver mediation for pyrrole selectivity, yet arene-alkene couplings often require harsh conditions.
Oxidant and catalyst efficiency
Balancing mild oxidants like air with turnover numbers challenges scalability. Xie et al. (2012) summarized solvent effects on Cu/Pd catalysts, highlighting inhibition issues. Zhou et al. (2022) advanced photoredox for C(sp3)-C(sp3) bonds, but recycling remains problematic.
Mechanistic understanding
Radical vs. two-electron pathways complicate optimization. Xie et al. (2012) proposed mechanisms for C-H cleavage influenced by catalysts and oxidants. Lv et al. (2023) used uranyl photocatalysis, but isotope labeling studies are scarce for confirming dehydrogenative paths.
Essential Papers
Oxidative cross-coupling/cyclization to build polysubstituted pyrroles from terminal alkynes and β-enamino esters
Jie Ke, Chuan He, Huiying Liu et al. · 2013 · Chemical Communications · 103 citations
A novel silver-mediated highly selective synthesis of polysubstituted pyrroles by the C-H/C-H oxidative cross-coupling/cyclization of terminal alkynes with β-enamino esters has been developed. This...
Enantioselective synthesis of arylglycine derivatives by direct C–H oxidative cross-coupling
Xiaohong Wei, Jun‐Jiao Wang, Shang‐Dong Yang · 2014 · Chemical Communications · 85 citations
A new method for the synthesis of chiral α-amino acid derivatives by enantioselective C–H arylation of <italic>N</italic>-aryl glycine esters with aryl boric acids by direct C–H oxidative cross-cou...
Transition Metal-Catalyzed C—H Oxidation Reactions
Ye‐Xiang Xie, Ren‐Jie Song, Jiannan Xiang et al. · 2012 · Chinese Journal of Organic Chemistry · 29 citations
Our recent progress in transition metal-catalyzed C-H oxidation reactions is summarized.The effect of catalysts, oxidants and solvents on the C-H bond oxidative cleavage reactions is described, and...
CuCl/air-mediated oxidative coupling reaction of imidazoheterocycles with <i>N</i>-aryl glycine esters
Jing Jiao, Junrong Zhang, Yanyan Liao et al. · 2017 · RSC Advances · 22 citations
A novel CuCl/air-mediated oxidative cross-coupling of imidazoheterocycles with glycine esters has been developed.
Synthesis, Structure, and Complexation of an S‐Shaped Double Azahelicene with Inner‐Edge Nitrogen Atoms
Takahiro Kawashima, Yuki Matsumoto, Takuma Sato et al. · 2020 · Chemistry - A European Journal · 20 citations
Abstract An S‐shaped double azahelicene ( 1 ) was synthesized in excellent yield by a palladium‐catalyzed double dehydrogenative C−H coupling reaction. The stereochemistry of 1 was confirmed to be ...
Visible-light-driven photoredox-catalyzed C(sp<sup>3</sup>)–C(sp<sup>3</sup>) cross-coupling of<i>N</i>-arylamines with cycloketone oxime esters
Sheng-Yun Zhou, Ding Zhang, Xiaojie Liu et al. · 2022 · Organic Chemistry Frontiers · 20 citations
A novel photoredox-catalyzed C(sp 3 )–C(sp 3 ) cross-coupling between N -arylamines and cycloketone oxime esters under mild conditions has been accomplished.
Metal catalyzed C–H functionalization on triazole rings
Anushka Koranne, Khushboo Kurrey, Prashant Kumar et al. · 2022 · RSC Advances · 18 citations
The present review covers advancement in the area of C–H functionalization on triazole rings, by utilizing various substrates with palladium or copper as catalysts, and resulting in the development...
Reading Guide
Foundational Papers
Start with Ke et al. (2013) for silver-mediated C-H/C-H pyrrole synthesis as the selective benchmark (103 citations), then Wei et al. (2014) for enantioselective arylglycine coupling, followed by Xie et al. (2012) for broad transition metal mechanisms.
Recent Advances
Study Zhou et al. (2022) for visible-light C(sp3)-C(sp3) photoredox couplings and Lv et al. (2023) for recyclable uranyl photocatalysis of amines-indoles.
Core Methods
Core techniques include Ag/Cu-mediated dehydrogenation (Ke 2013, Jiao 2017), chiral ligand-enabled enantioselectivity (Wei 2014), and photoredox with oxime esters (Zhou 2022).
How PapersFlow Helps You Research C-H Oxidative Cross-Coupling
Discover & Search
PapersFlow's Research Agent uses searchPapers and citationGraph to map high-citation works like Ke et al. (2013, 103 citations) and its forward citations for pyrrole synthesis variants. exaSearch uncovers niche couplings like scandium-catalyzed alkylations (Wei et al., 2017), while findSimilarPapers links enantioselective methods (Wei et al., 2014) to photoredox advances (Zhou et al., 2022).
Analyze & Verify
Analysis Agent employs readPaperContent to extract oxidant effects from Xie et al. (2012), then verifyResponse with CoVe checks mechanistic claims against Ke et al. (2013). runPythonAnalysis processes yield data from Jiao et al. (2017) via pandas for statistical trends, with GRADE scoring evidence strength for catalyst comparisons.
Synthesize & Write
Synthesis Agent detects gaps like limited C(sp3)-C(sp3) scope beyond Zhou et al. (2022), flagging contradictions in radical pathways. Writing Agent uses latexEditText and latexSyncCitations to draft reaction schemes citing Wei et al. (2014), with latexCompile generating publication-ready overviews and exportMermaid for mechanistic diagrams.
Use Cases
"Plot yields vs. oxidant type from recent C-H oxidative couplings of glycine esters"
Research Agent → searchPapers('glycine ester oxidative coupling') → Analysis Agent → runPythonAnalysis(pandas/matplotlib on extracted data from Jiao et al. 2017, Wei et al. 2014) → yield trend plot and stats summary.
"Draft LaTeX review section on silver-mediated pyrrole synthesis mechanisms"
Research Agent → citationGraph(Ke et al. 2013) → Synthesis Agent → gap detection → Writing Agent → latexEditText + latexSyncCitations(Ke 2013, Xie 2012) + latexCompile → formatted LaTeX section with scheme.
"Find GitHub repos with code for photoredox C-H coupling simulations"
Research Agent → searchPapers('photoredox C-H cross-coupling') → Code Discovery → paperExtractUrls(Zhou 2022) → paperFindGithubRepo → githubRepoInspect → list of DFT simulation scripts for radical pathways.
Automated Workflows
Deep Research workflow scans 50+ papers via searchPapers on 'C-H oxidative cross-coupling pyrrole', delivering structured reports with citation clusters around Ke et al. (2013). DeepScan's 7-step chain analyzes Jiao et al. (2017) with readPaperContent → CoVe verification → GRADE scoring for Cu/air scalability. Theorizer generates hypotheses on uranyl photocatalysis (Lv et al., 2023) by synthesizing mechanisms from Xie et al. (2012).
Frequently Asked Questions
What defines C-H oxidative cross-coupling?
It couples two C-H bonds to form C-C bonds via dehydrogenation with oxidants and catalysts, bypassing prefunctionalized reagents (Ke et al., 2013).
What are common methods and catalysts?
Silver for pyrrole cyclization (Ke et al., 2013), Cu/air for imidazoheterocycle-glycine couplings (Jiao et al., 2017), and photoredox for C(sp3) bonds (Zhou et al., 2022).
What are key papers?
Ke et al. (2013, 103 citations) on Ag-mediated pyrroles; Wei et al. (2014, 85 citations) on enantioselective arylglycines; Xie et al. (2012, 29 citations) on transition metal C-H oxidation.
What open problems exist?
Scalable mild oxidants without metals, broad enantioselectivity beyond arylglycines (Wei et al., 2014), and full mechanistic clarity for photoredox paths (Zhou et al., 2022).
Research Catalytic C–H Functionalization Methods with AI
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