Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• the synthesis of trifluoromethyl aromatic acyloins. Maekawa’s group [24] developed a tandem reaction of the reductive coupling between arylaldehydes and ethyl trifluoroacetate in the presence of magnesium and chlorotrimethylsilane, followed by desilylation to produce the trifluoromethyl aromatic

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• equivalents of water interrupted the cyclization step and led entirely to reductively coupled alkenylated ring-opened products. Interestingly, when this methodology was applied to the ester-bearing oxabicyclic 1a, the anticipated reductive coupling product was not detected; instead, bicyclic γ-lactone 4 was

• solely observed (Scheme 1). This unprecedented lactone is presumed to be generated through the expected reductive coupling to generate the ring-opened intermediate 5 which undergoes subsequent intramolecular lactonization with the distal ester group. In the same year, Cheng and co-workers observed the

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• reported. During this study, they also looked into the asymmetric total synthesis of albolic acid (178) and ceroplastol II (179). Only one paper reported their total synthesis, using a reductive coupling of aldehydes for the synthesis of the eight-membered ring with an excellent yield of 96% [82]. However

Electrochemical formal homocoupling of sec-alcohols

• Kosuke Yamamoto,
• Kazuhisa Arita,
• Masashi Shiota,
• Masami Kuriyama and
• Osamu Onomura

Beilstein J. Org. Chem. 2022, 18, 1062–1069, doi:10.3762/bjoc.18.108

• electrolysis; Introduction Carbon–carbon bond formation is one of the most fundamental and important reactions in synthetic organic chemistry. Reductive coupling of carbonyl compounds known as pinacol coupling would be a powerful method to construct vic-1,2-diol scaffolds through C–C bond formation [1][2

• ][16][17][18]. In addition to the reductive coupling of carbonyl compounds, oxidative homocoupling reactions of benzyl alcohols under transition metal- or semiconductor-based photoredox catalysis have been demonstrated as attractive approaches to access vic-1,2-diols [19][20][21][22][23

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• by cyclic voltammetry (Table 3) and acceptors 2 revealed no reduction peaks from 0 to −2.00 V vs SCE [5][6]. Therefore, this electroreductive coupling is initiated by the reduction of compounds 1. There are two possible reaction mechanisms for the reductive coupling of 1 with 2a as illustrated in

Cs₂CO₃-Promoted reaction of tertiary bromopropargylic alcohols and phenols in DMF: a novel approach to α-phenoxyketones

• Ol'ga G. Volostnykh,
• Olesya A. Shemyakina,
• Anton V. Stepanov and
• Igor' A. Ushakov

Beilstein J. Org. Chem. 2022, 18, 420–428, doi:10.3762/bjoc.18.44

• reductive coupling of acid halides with ketones [36][37] and acetolyses of α-phenoxy-α-diazoketones [38] were also employed. Recently, F. P. Cossío et al. [39] have described a method for the preparation of benzo[b]furans by thermal heating of a dispersion of α-phenoxyketones in Al2O3. We involved the

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• authors (Scheme 29). The latter steps of reductive coupling cascades of unactivated olefins with electron-deficient olefins under MHAT conditions involve the reduction of the radical generated at the α-position of an EWG to an enolate that could be engaged in further reactions (i.e., Scheme 23 to Scheme

Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• unprecedented reductive coupling of N-benzylidene-[1,1'-biphenyl]-2-amines with an aliphatic amine. The presence of a phenyl substituent in the aniline moiety of the substrate was critical for the reactivity. The reaction proceeded via radical–radical cross-coupling of α-amino radicals generated by proton

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• derivatives [18][19]. Towards the synthesis of S-diazocines (Figure 1), two general approaches could be derived from the well investigated azobenzene preparation methods: a) Reductive coupling of two nitro groups or b) oxidative coupling of two amino groups [20]. To cleanly form N=N bonds by reduction of

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• generated by the reductive coupling of in situ-formed RCF2CF2MgCl·LiCl with various electrophiles [22][23]. Our group revealed that commercially available 4-bromo-3,3,4,4-tetrafluorobut-1-ene (1) underwent a Cu(0)-mediated cross-coupling reaction with aromatic iodides in DMSO at 160 °C in a sealed-tube

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• developed (e.g., reductive coupling [22][23][24][25][26][27][28], formal hydromethylation [29], cycloisomerization [8][30][31], hydrooximation [32], hydroheteroarylation [28][33][34][35], hydroarylation [36][37][38], and cross-coupling [37]). Many of these transformations have found applications in

• hexafluorophosphate (6d) to provide the reductive coupling product 4m in 50% yield (Table 1, entry 14). Conclusion In summary, we have demonstrated that under a consistent set of conditions, the Co(acac)2–TBHP–Et3SiH system effects a diverse array of Markovnikov-selective hydrofunctionalization reactions of

• unactivated alkenes (H–X addition, X = H, F, Cl, Br, I, O, S, Se, N, and C). We have also reported the first reductive coupling reactions of alkenes and aryldiazonium salts under HAT conditions. These transformations proceed in high regioselectivity and efficiency. Further efforts will focus on expanding the

Transition-metal-free synthesis of 3-sulfenylated chromones via KIO₃-catalyzed radical C(sp²)–H sulfenylation

• Yanhui Guo,
• Shanshan Zhong,
• Li Wei and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2017, 13, 2017–2022, doi:10.3762/bjoc.13.199

• ), further confirming that a radical intermediate was generated during the reaction process. According to the results obtained in the control experiments, the mechanism for this domino reaction is proposed (Scheme 4). As one of the key steps, the reductive coupling of two sulfonyl hydrazine molecules may

Cathodic reductive coupling of methyl cinnamate on boron-doped diamond electrodes and synthesis of new neolignan-type products

• Taiki Kojima,
• Rika Obata,
• Tsuyoshi Saito,
• Yasuaki Einaga and
• Shigeru Nishiyama

Beilstein J. Org. Chem. 2015, 11, 200–203, doi:10.3762/bjoc.11.21

• -type derivatives. These results provide an example for an electroorganic synthesis using cathodic reductive coupling on a boron-doped diamond electrode. Expected coupling products from one-electron oxidation (left) and one-electron reduction (right) of C6–C3 compounds. Chemical conversion of (±)-2 into

An improved procedure for the preparation of Ru(bpz)₃(PF₆)₂ via a high-yielding synthesis of 2,2’-bipyrazine

• Danielle M. Schultz,
• James W. Sawicki and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2015, 11, 61–65, doi:10.3762/bjoc.11.9

• ; palladium; photocatalysis; reductive coupling; Findings Visible light-photoredox catalysis using transition metal chromophores is rapidly becoming recognized as an important strategy in organic synthesis [1][2][3][4][5]. This approach towards reaction design enables the facile generation and exploitation

• of bpz. An improved synthesis of this ligand would be useful both in the context of the growing interest in photoredox catalysis as well as other organometallic and inorganic applications of bpz-supported transition metal complexes. Our optimization studies for the reductive coupling of 2

• complex 2, we were pleased to find that the optimal conditions for the synthesis of 2,2’-bipyrazine translated smoothly to the reductive coupling of a variety of pyridyl electrophiles. Table 2 demonstrates the application of these reaction conditions to the syntheses of a number of electron-deficient

A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1’-binaphthalene-2,2’-diamines (BINAMs)

• Youhei Takeda,
• Masato Okazaki,
• Yoshiaki Maruoka and
• Satoshi Minakata

Beilstein J. Org. Chem. 2015, 11, 9–15, doi:10.3762/bjoc.11.2

• metal complexes through the coordination at the diazene unit [15][16][17]. Taking 7,8-diaza[5]helicene as an example, conventional methodologies of preparing such compounds (Scheme 2) involve i) reductive coupling of 2-nitronaphthalenes using strong reductants like Zn dust [1][18] and PH3 [19], ii

Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer

• Florian Hamon,
• Claire Blaszkiewicz,
• Marie Buchotte,
• Estelle Banaszak-Léonard,
• Hervé Bricout,
• Sébastien Tilloy,
• Eric Monflier,
• Christine Cézard,
• Laurent Bouteiller,
• Christophe Len and
• Florence Djedaini-Pilard

Beilstein J. Org. Chem. 2014, 10, 2874–2885, doi:10.3762/bjoc.10.304

• azobenzene dicarboxylate and the influence of photoisomerization of the linker on the conformation and binding behavior of the CD dimer. Results and Discussion The AZO-CDim 1 synthesis was performed as follows: 4,4’-azobenzenedicarboxylic acid was first obtained by reductive coupling of 4-nitrobenzoic acid

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• reactions using zirconocene species have been reported, in particular for the reductive coupling of alkenes or alkynes with other unsaturated compounds [40][41][42][43]. On the other hand, carbozirconation of alkynes via reaction of zirconacyclopentenes with alcohols, allyl ethers, homoallyl bromides, vinyl

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• which can be cyclized to compounds 7 in yields of up to 50% (over 4 steps) [42]. Other methods involve the use of stoichiometric zirconocene dichloride [43], the reductive coupling of alkynes to enones followed by ozonolysis and Paal–Knorr cyclization [21] or the reaction of vinylazides with aldehydes

A new manganese-mediated, cobalt-catalyzed three-component synthesis of (diarylmethyl)sulfonamides

• Antoine Pignon,
• Erwan Le Gall and
• Thierry Martens

Beilstein J. Org. Chem. 2014, 10, 425–431, doi:10.3762/bjoc.10.39

• imine results from the reaction of the tosylamide with the aldehyde, and the biaryl was formed by reductive coupling of the starting halide. A preformed imine can be used in the process (Table 2, entry 3, result in brackets), indicating that this species might be the reactive electrophilic intermediate

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• decarboxylation enables construction of the C15−C16 bond by an aldol reaction. The product of this transformation is of the correct oxidation state and potentially three steps removed from the targeted epoxide fragment. Keywords: catalysis; natural product; nickel; reductive coupling; ripostatin A; synthesis

• potentially sensitive 1,4,7-triene by masking it as a cyclopropyldiene, then unveiling the skipped triene portion via a 1,5-hydrogen rearrangement (Figure 3). This strategy would allow us to take advantage of the high regioselectivity in enyne–epoxide reductive coupling reactions. Furthermore, the proposed

• cyclopropane unit had not been previously tested under nickel-catalyzed reductive coupling conditions. Nickel(0) is known to catalyze the rearrangement of vinylcyclopropanes to cyclopentenes; however, activating substituents are commonly required [19][20][21]. Furthermore, application of a proposed 1,5

Amino-substituted diazocines as pincer-type photochromic switches

• Hanno Sell,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1–7, doi:10.3762/bjoc.9.1

• quantitatively in ortho position to the ethylene bridge, forming 1,2-bis(2-nitro-4-aminophenyl)ethane (3) [11]. Intramolecular reductive coupling of the nitro groups to form the azo unit proceeds with notoriously low yields. The most frequently used procedure using Zn as the reducing agent in Ba(OH)2 [12] or

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• heterocumulenes [71]. Reductive coupling of two CS2 units at (PNP)Ir═C(H)Ot-Bu [73]. Possible routes to C–H functionalization by 1,2-addition across a polarized metal–element multiple bond. Alkoxycarbene formation by double C–H activation at (PNP)Ir [88]. Catalytic oxidation of MTBE by multiple C–H activations

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• which two, or all three, units are identical [22]. The method was based on the reductive coupling of silylated derivatives of 2,6-hydroxymethylphenols, in which R is t-Bu, Me, benzyl (Bz), phenyl (Ph), or a halide, as shown in Scheme 3. The reaction takes place under conditions of high dilution at −78

Directed ortho,ortho'-dimetalation of hydrobenzoin: Rapid access to hydrobenzoin derivatives useful for asymmetric synthesis

• Inhee Cho,
• Labros Meimetis,
• Lee Belding,
• Michael J. Katz,
• Travis Dudding and
• Robert Britton

Beilstein J. Org. Chem. 2011, 7, 1315–1322, doi:10.3762/bjoc.7.154

• which arises through the deprotonation of benzyl chloride by 8 and reaction of the resulting benzyl anion with a second equivalent of benzyl chloride. Likewise, attempts to effect a reductive coupling of the tetralithio intermediate to afford the dihydrophenanthrenediol 23 [22] with the aid of various