gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• University, 3-4-1 Kowakae, Higashi-osaka, Osaka, 577-8502, Japan 10.3762/bjoc.20.194 Abstract gem-Difluorination of carbon–carbon triple bonds was conducted using Brønsted acids, such as Tf2NH and TfOH, combined with Bu4NBF4 as the fluorine source. The electrochemical oxidation of a Bu4NBF4/CH2Cl2 solution

• containing alkyne substrates could also give the corresponding gem-difluorinated compounds (in-cell method). The ex-cell electrolysis method was also applicable for gem-difluorination of alkynes. Keywords: carbon–carbon triple bonds; chemical method; electrochemistry; gem-difluorination; Introduction

• blocks for further transformations. We have focused on the investigation of gem-difluorination of carbon–carbon triple bonds, because this procedure is one of the most simple but powerful and straightforward methods. In addition, there have been a few reports in the literature that seem to mainly rely on

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• isolated from THF solution. Keywords: alkyne metathesis; ferrocene; homogeneous catalysis; molybdenum; terminal alkynes; Introduction Alkyne metathesis, the reversible making and breaking of carbon–carbon triple bonds, is clearly gaining more attention. Not only could a great number of active catalysts

Efficient catalytic alkyne metathesis with a fluoroalkoxy-supported ditungsten(III) complex

• Henrike Ehrhorn,
• Janin Schlösser,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2018, 14, 2425–2434, doi:10.3762/bjoc.14.220

• progress in the past decades [1][2][3][4][5], the synthetic potential of alkyne metathesis has been growing only recently [6][7][8][9][10][11]. Alkyne metathesis represents a transition-metal-catalyzed transformation in which carbon–carbon triple bonds are cleaved and formed under mild conditions via

Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• not the same as carbon–carbon triple bonds. But, when I took a calming breath and looked again, I embraced the curvature and just kept on drawing (Figure 5b). Before I really knew what was happening, the alternating benzenes and triazoles quickly and quietly generated a circle resembling a new

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• - pentamethylcyclopentadienyl), showing good communication still well past five carbon–carbon triple bonds between the metal centres. Reduction: As expected, compound 3b was found to be non-reducible within the potential window defined by the solvent-supporting electrolyte system (CH2Cl2, Bu4NPF6). The reduction of the

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• triple bonds [49]. Imine-based MCRs have received considerable attention in recent years [50]. The increasing interest in imine-based MCRs can be attributed to the easy preparation (even in situ) of many differently substituted derivatives from commercially available aldehydes and amines. This leads to

• mechanism. This part of the review is divided in sections related to the nature of the activated functionalities. Reaction involving activation of carbon–carbon multiple bonds. This section primarily discusses cycloisomerization reactions involving the addition of imines to silver-activated carbon–carbon

Cascade radical reaction of substrates with a carbon–carbon triple bond as a radical acceptor

• Hideto Miyabe,
• Ryuta Asada and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2013, 9, 1148–1155, doi:10.3762/bjoc.9.128

• and limitation of the cascade transformation of hydroxamate esters with carbon–carbon triple bonds, the substrates of choice were 5, 6A–C, 7 and 8 having hydroxamate ester functionality (Figure 3). At first, we studied the cascade reaction of 5 with an acryloyl moiety and 6A–C with a methacryloyl

Gold-catalyzed oxidation of arylallenes: Synthesis of quinoxalines and benzimidazoles

• Dong-Mei Cui,
• Dan-Wen Zhuang,
• Ying Chen and
• Chen Zhang

Beilstein J. Org. Chem. 2011, 7, 860–865, doi:10.3762/bjoc.7.98

• –carbon triple bonds by homogeneous gold catalysts was reported recently [28][29][33]. To the best of our knowledge, gold and other transition metal-catalyzed oxidations of allenes have not been reported [37][38]. In the context of ongoing studies on metal-catalyzed atom-economical reactions, we have been

• particular, water as a nucleophilic reagent has been used in the addition of alkynes and allenes [16][17][18]. In contrast, gold-catalyzed oxidation chemistry has been less well developed [25][26][27][28][29][30][31][32][33][34][35][36], although oxidative cleavage of carbon–carbon double bonds and carbon

Construction of cyclic enones via gold-catalyzed oxygen transfer reactions

• Leping Liu,
• Bo Xu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2011, 7, 606–614, doi:10.3762/bjoc.7.71

• increased substantially and gold catalysis has become one of the hottest research fields in synthetic organic chemistry [34][35][36][37][38][39][40][41][42]. Due to their unique alkynophilicity, gold catalysts are especially suited to the activation of carbon–carbon triple bonds. Gold-catalyzed formation of