Cross‐Coupling Reactions to sp Carbon Atoms

Sonogashira, Kenkichi

doi:10.1002/9783527612222.ch5

Cited by 216 publications

(23 citation statements)

References 78 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The development of Cu-catalyzed or -mediated coupling reactions has been studied for more than a century, since the pioneering work of Ullmann, Goldberg, and Hurtley in modern Cu chemistry . Cu catalysis is well accepted as a practical and efficient method for the synthesis of various natural products, medicinal molecules, and organic functional materials; for example, the Glaser–Hay and Sonogashira coupling reactions, which use Cu salts to catalyze alkyne coupling, have been widely used for the construction of internal alkynes and diynes . However, most research on these reactions is devoted to synthetic methodology, and more attention needs to be paid to the mechanistic study of Cu/alkyne chemistry …”

Section: Introductionmentioning

confidence: 99%

Mechanism of Synergistic Cu(II)/Cu(I)-Mediated Alkyne Coupling: Dinuclear 1,2-Reductive Elimination after Minimum Energy Crossing Point

Bai

Zhu

et al. 2016

J. Org. Chem.

View full text Add to dashboard Cite

An in-depth theoretical study of synergistic Cu(II)/Cu(I)-mediated alkyne coupling was performed to reveal the detailed mechanism for C-C bond formation, which proceeded via an unusual dinuclear 1,2-reductive elimination. Because the reactant for dinuclear 1,2-reductive elimination was calculated to be triplet while the products were singlet, the minimum energy crossing point (MECP) was introduced to the Cu/TMEDA/alkyne system to clarify the spin crossing between triplet state and singlet state potential energy surfaces. Computational results suggest that C-H bond cleavage solely catalyzed by the Cu(I) cation is the rate-determining step of this reaction and Cu(II)-mediated dinuclear 1,2-reductive elimination after the MECP is a facile process. These conclusions are in good agreement with our previous experimental results.

show abstract

Section: Introductionmentioning

confidence: 99%

Mechanism of Synergistic Cu(II)/Cu(I)-Mediated Alkyne Coupling: Dinuclear 1,2-Reductive Elimination after Minimum Energy Crossing Point

Bai

Zhu

et al. 2016

J. Org. Chem.

View full text Add to dashboard Cite

show abstract

“…A lkyne is an important functional group in organic synthesis and is also found in natural products and pharmaceuticals 1 . Among many available synthetic methodologies, the Sonogashira reaction is one of the most reliable transformations for the synthesis of internal alkynes 2 . Initially developed for coupling of terminal alkynes with aryl/vinyl (pseudo)halides in the presence of Pd/Cu 3 or Cu catalyst alone 4,5 , the reaction has subsequently been extended to alkyl bromides/iodides ( Fig.…”

mentioning

confidence: 99%

Functionalization of remote C(sp3)-H bonds enabled by copper-catalyzed coupling of O-acyloximes with terminal alkynes

Torres‐Ochoa

Wang

et al. 2020

Nat Commun

View full text Add to dashboard Cite

Transition metal catalyzed Sonogashira cross-coupling of terminal alkynes with aryl(vinyl) (pseudo)halides has been successfully extended to alkyl halides for the synthesis of functionalized internal alkynes. The direct alkynylation of remote unfunctionalized sp 3 carbon by terminal alkynes remains difficult to realize. We report herein an approach to this synthetic challenge by developing two catalytic remote sp 3 carbon alkynylation protocols. In the presence of a catalytic amount of Cu(I) salt and a tridentate ligand (tBu 3-terpyridine), O-acyloximes derived from cycloalkanones and acyclic ketones are efficiently coupled with terminal alkynes to afford a variety of γand δ-alkynyl nitriles and γ-alkynyl ketones, respectively. These reactions proceed through a domino sequence involving copper-catalyzed reductive generation of iminyl radical followed by radical translocation via either β-scission or 1,5hydrogen atom transfer (1,5-HAT) and copper-catalyzed alkynylation of the resulting translocated carbon radicals. The protocols are applicable to complex natural products.

show abstract

“…The ethynediyl-linked 2'-deoxyuridines ( 3a ) were prepared first by Sonogashira coupling at 37 °C, [xxxvii] as we also observed that elevated temperature leads to a cyclization product. [36],[xxxviii] Although the ethynediyl-linked dimer 3a was obtained in 64% yield, due to its poor solubility synthesis of ribose-acetylated derivative 3b was explored.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and EPR Studies of 2′‐Deoxyuridines with Alkynyl, Rodlike Linkages

Sniady

Sevilla

Meneni

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

Sonogashira coupling of diacetyl 5-ethynyl-2'-deoxyuridine with diacetyl 5-iodo-2'-deoxyuridine gave the acylated ethynediyl-linked 2'-deoxyuridine dimer (3b) (63%) that was deprotected with ammonia/methanol to ethynediyl-linked 2'-deoxyuridines (3a) (79%). Reaction of 5-ethynyl-2'-deoxyuridine (1a) with 5-iodo-2'-deoxyuridine gave the furopyrimidine linked to 2'-deoxyuridine (78%). Catalytic oxidative coupling of 1a (O2, CuI, Pd/C, DMF) gave the butadiynediyl-linked 2'-deoxyuridines (4) (84%). Double Sonogashira coupling of 5-iodo-2'-deoxyuridine with 1,4-bis(ethynyl)benzene gave 1,4-phenylenediethyne-bridged 5-ethynyl-2'-deoxyuridines (5, 83%). Cu-catalyzed cycloisomerization of dimers 4 and 5 gave their furopyrimidine derivatives. One electron addition to 1a, 3a and 4 gave the anion radical whose ESR spectra showed the unpaired electron largely localized at C6 of one uracil ring (17 G doublet) at 77 K. For the ethynediyl- and butadiynyl-linked uridines 3a and 4 the ESR spectra of their one electron oxidized species at 77 K showed that the unpaired electron is delocalized over both rings. Thus structures 3a and 4 provide an efficient electronic link for hole conduction between the uracil rings. However, for the excess electron, an activation barrier prevents coupling to both rings. These dimeric structures could provide a gate that could separate hole transfer from electron transport between strands in DNA systems. In the crystal structure of acylated dimer 3b the bases were found in the anti position to each other across the ethynyl link. Similar anti conformation was preserved in the derived furopyrimidine–deoxyuridine dinucleoside.

show abstract

Cross‐Coupling Reactions to sp Carbon Atoms

Cited by 216 publications

References 78 publications

Mechanism of Synergistic Cu(II)/Cu(I)-Mediated Alkyne Coupling: Dinuclear 1,2-Reductive Elimination after Minimum Energy Crossing Point

Mechanism of Synergistic Cu(II)/Cu(I)-Mediated Alkyne Coupling: Dinuclear 1,2-Reductive Elimination after Minimum Energy Crossing Point

Functionalization of remote C(sp3)-H bonds enabled by copper-catalyzed coupling of O-acyloximes with terminal alkynes

Synthesis and EPR Studies of 2′‐Deoxyuridines with Alkynyl, Rodlike Linkages

Contact Info

Product

Resources

About