Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• (Table 2), this reaction, most probably, proceeds through an SN2 pathway, where “pure” heteroaromatic cation B is not formed. At least the reaction may go through late transition state, in which the C–O bond in the CH2O+H2 group is rather elongated, resulting in a larger positive charge on this carbon

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• in the ionic liquid were involved in the reaction. It was therefore proposed that an interaction of the quaternary ammonium center with the carbonyl oxygen of glycerol carbonate (GlyC) could weaken the C=O bond (Scheme 15). It is worth mentioning that glycidol was previously obtained at much higher

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

• Sonia L. Repetto,
• James F. Costello,
• Craig P. Butts,
• Joseph K. W. Lam and
• Norman M. Ratcliffe

Beilstein J. Org. Chem. 2016, 12, 1467–1475, doi:10.3762/bjoc.12.143

• rates of hydrolysis for six-membered 15 and 8 could be explained with the kinetic anomeric effect. Consistent with this, the X-ray crystal structure of an analogous yet conformationally constrained bicyclic orthoester possesses an unusually elongated axial C─O bond (Figure 2a), which undergoes

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

• Haipan Zhu,
• Peile Du,
• Jianjun Li,
• Ziyang Liao,
• Guohua Liu,
• Hao Li and
• Wei Wang

Beilstein J. Org. Chem. 2016, 12, 1340–1347, doi:10.3762/bjoc.12.127

• vinylcyclopropanes with α,β-unsaturated aldehydes for the first time. The combination of a chiral iminium catalyst, which activates the C=C bond and blocks the C=O bond in enals, and a Lewis acid promoting to open the vinylcyclopropanes enables the annulation process to proceed with the challenging C=C bond. A high

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• new C–O bond (Scheme 20) [62]. A wide range of benzyl silyl ethers and diazo compounds were tested providing the desired 2,3-dihydrobenzofuran in good yields and excellent diastereo- and enantioselectivity. Later, this strategy was further used by Davies, Zakarian and coworkers to access the total

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• catalytic cysteine. Subsequently, lactonization can take place. It is assumed that an enolate exists as an intermediate in the formation of the C–O bond [88]. Even though for both enzymes no experimental evidences for the chronological order of the two condensation reactions exist, it can be expected that

Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes

• H. Surya Prakash Rao and
• A. Veera Bhadra Rao

Beilstein J. Org. Chem. 2016, 12, 496–504, doi:10.3762/bjoc.12.49

• with simultaneous C–O bond cleavage subsequently occurs in 16 to give the triarylmethane 11 and copper(OH)(OTf) (17). The reaction of 17 with arylboronic acid 10 regenerates 15 and results in the formation of stable boric acid. The driving force for the triarylmethane formation is the generation of a

Copper-catalyzed aminooxygenation of styrenes with N-fluorobenzenesulfonimide and N-hydroxyphthalimide derivatives

• Yan Li,
• Xue Zhou,
• Guangfan Zheng and
• Qian Zhang

Beilstein J. Org. Chem. 2015, 11, 2721–2726, doi:10.3762/bjoc.11.293

• aminooxygenation reaction of alkenes with phthalimide and (diacetoxyiodo)benzene through cis-aminopalladation and SN2 C–O bond formation [34]. In 2013, Zhu and co-workers described an n-Bu4NI-catalyzed aminooxygenation of inactive alkenes with benzotriazole and water which underwent a nitrogen-centred radical

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• ) are established catalysts of C–O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C–N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• pyramidal geometry with the copper ion lying slightly above the basal plane formed by 4 nitrogen atoms (average dCu···N 2.019 Å), while an oxygen atom of a carboxylate occupies the axial site (dCu···O 2.294 Å). The oxygen atom of the C=O bond is participating in one intramolecular (dCO···HN 2.140 Å) and one

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

• Ya Lin Tnay,
• Gim Yean Ang and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

• spirocyclization of the alkoxy radical D onto the benzene ring affords cyclohexadienyl radical F, oxygenation of which followed by C=O bond formation finally provides the oxaspirocyclohexadienone product 3a. Whereas, the oxidation of the benzylic radical B by the existing Cu(II) species to carbocation G and

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• , with special emphasis on the studies published after 2000. The starting compound, which donates a carbon atom for the formation of a new C–O bond, is called the CH-reagent or the C-reagent, and the compound, an oxygen atom of which is involved in the new bond, is called the OH-reagent or the O-reagent

• reactions of CH- and OH-reagents, closely related C–H activation processes involving intermolecular C–O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.). Keywords: acyloxylation; alkoxylation

• ; C–H functionalization; C–O bond formation; cross-dehydrogenative coupling; oxidative cross-coupling; Introduction The development of methods for the cross-dehydrogenative coupling (CDC; or oxidative cross coupling) is an important field of modern organic chemistry. These terms commonly refer to

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• carbon, and the carbonyl group of the MPA unit as well as the methine proton (CH) of the alcohol moiety [the substrate (+)-5 part] are all situated in the same plane, whereas the phenyl ring is ca. perpendicular to the C=O bond and coplanar with the CαH bond. Both the methoxy and the carbonyl group are

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• of vinyl-terminated SAMs has been demonstrated, e.g., through surface modification of radicals generated by C–O bond thermolysis [17] and in a more controlled sense via olefin cross metathesis/enyne metathesis [18] of mixed vinyl and acetylenyl-terminated SAMs followed by Diels–Alder modifications of

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• formation of a C,O-bond and generation of the five-membered heterocycle. Hydroxy, carboxy and oxime moieties were tested as nucleophiles for this reaction, leading to the corresponding tetrahydrofurans, γ-lactones and isoxazolines, respectively. The chemistry depicted in Scheme 13 was also used for the

Regio- and stereoselective synthesis of new diaminocyclopentanols

• Evgeni A. Larin,
• Valeri S. Kochubei and
• Yuri M. Atroshchenko

Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262

• of intermediate 16 formed from Zn(ClO4)2-catalyzed C–O bond cleavage followed by the attack of the N,N-disubstituted amino moiety towards C2. The approach of the N,N-disubstituted amino group to C2 would be more favorable than that of the nucleophile (morpholine) to either oxirane carbon atoms

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• developed is limited to benzylic, α-carbonyl, and α-cyanoalcohols; with other alcohols a slow partial C–F bond reduction in the 3,5-bis(trifluoromethyl)benzoate moiety occurs. Keywords: C–O bond activation; deoxygenation; photochemistry; photoredox catalysis; visible light; Introduction The dwindling

• moiety of the benzoate – and not in the desired anti-bonding σ*(C–O) (Scheme 5). Protonation of the radical anion would lead to a neutral radical species, which in the calculations reflects in a shift of electron density towards the C–O bond to be cleaved. Consequently, a mixture of acetonitrile/water

• example under typical conditions 3,5-bis(trifluoromethyl)benzoates such as 10 gave 12 where one trifluoromethyl group was completely reduced to a methyl group in 52% yield (Scheme 7). Apparently, electron transfer to the benzoate group is still possible however, the subsequent C–O bond cleavage does not

Efficient CO₂ capture by tertiary amine-functionalized ionic liquids through Li⁺-stabilized zwitterionic adduct formation

• Zhen-Zhen Yang and
• Liang-Nian He

Beilstein J. Org. Chem. 2014, 10, 1959–1966, doi:10.3762/bjoc.10.204

• cm−1 was assigned to the stretching vibration of the C=O bond in the zwitterionic product. In addition, a distinct broad band at around 2118 cm−1 corresponding to the ammonium cation was observed in the presence of water. To gain deeper insight into the reaction mechanism of CO2 absorption with

Proton transfers in the Strecker reaction revealed by DFT calculations

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 1765–1774, doi:10.3762/bjoc.10.184

• complex 1. The reaction begins with the addition of NH3 to the carbonyl carbon of acetaldehyde to form a Mulliken charge-transfer complex 2. This complex was firstly proposed here. In 2, the C–O bond is elongated to1.345 Å, which has an alkoxide character and the complex is not stable in the gas phase

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• other hand the oxidation of 1b with Oxone in methanol and water gave the β-methoxy alcohol through transformation of the C–Se bond into a C–O bond even in the presence of a weak nucleophile like the hydroxy ion [6]. The oxidation of γ-(phenylseleno)alkyl tosylamide 1d with MMPP (2.4 equiv) in ethanol

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• We report an efficient Pd-catalyzed C(sp2)–H activation/C–O bond formation for the synthesis of ethoxy dibenzooxaphosphorin oxides from 2-(aryl)arylphosphonic acid monoethyl esters under aerobic conditions. Keywords: C–H activation; catalysis; cyclization; palladium; phosphorus heterocyclic compound

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

• to the C=O bond of an oxocarbenium intermediate II, formed by a Au-catalyzed reaction between aldehydes and orthoformate 23. Other multicomponent processes Silver assisted multicomponent reactions Newly reported and notable synthetic strategies based on silver-mediated processes are discussed in this

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• -K reduction in the former step is the conversion of the C=O bond to the C=N–NH2 group. The latter step involves a shift of two hydrogen atoms from the terminal nitrogen atom to the carbon and the simultaneous extrusion of an N2 molecule. The Huang-Minglon modification is an alternative and

Gold-catalyzed reaction of oxabicyclic alkenes with electron-deficient terminal alkynes to produce acrylate derivatives

• Yin-wei Sun,
• Qin Xu and
• Min Shi

Beilstein J. Org. Chem. 2013, 9, 1969–1976, doi:10.3762/bjoc.9.233

• these previous findings, we envisaged that oxabicyclic alkenes could also react with electron-deficient alkynes in the presence of gold catalysts to generate a new C–C or C–O bond thereby releasing the oxabicyclic alkenes of their ring strain. In this paper, we report the formation of (Z)-acrylate

• derivatives in the gold catalyzed intermolecular reaction of oxabicyclic alkenes with electron-deficient terminal alkynes under mild conditions [69][70][71][72][73][74][75][76] (Scheme 1). Results and Discussion To generate a new C–O bond in the reaction of oxabicyclic alkene 1a with electron-deficient