A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• derivatives of L-tartaric acid anhydrides in 1986. A promising asymmetric induction was achieved for the oxidation of sulfides 23 to sulfoxides 24. This marked the beginning of an era of asymmetric oxidation of sulfides. However, the presence of C2 symmetry in the chiral unit is essential to obtain decent

• enantioselectivity [24]. Later, Kita et al. used chiral tartaric acid derivatives to synthesize chiral I(V) reagents 2 from PhIO2. This represented the first example of the catalytic use of chiral hypervalent reagents in the oxidation of sulfides to sulfoxides with decent enantioselectivities (ees, Scheme 2a). The

• sulfides to sulfoxides with good yields but with poor enantioselectivity (Scheme 2b) [27]. Later, Zhdankin et al. synthesized different classes of chiral I(V) reagents 4 based on various amino acids as sources of chirality. The oxidation of the readily available 2-iodobenzamides (synthesized from amino

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• . General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways. Keywords: disulfides; photocatalysis; sulfones; sulfoxides; thiols; visible light

• disulfide, thioamide derivatives and sulfides Disulfides and thiosulfates Sulfoxides Sulfinic acids, sulfinate salts and sulfinamides Sulfonyl halides, sulfonyl hydrazines, thionyl chloride and sulfur dioxide C–S bond formations initiated by irradiation with light of wavelengths shorter than 380 nm or by

• radical initiators as well as photocatalytic reactions, where sulfur-containing substrates act as a sacrificial agent are not discussed in this review [23][24][25][26][27][28]. Review Thiols Formation of sulfides and sulfoxides A large number of photocatalytic C–S bond-forming methods report the

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• the type of glycosyl donors that can undergo a preactivation-based chemoselective glycosylation with an emphasis on thioglycosides due to their wide applicability. Preactivation of glycosyl sulfoxides: early success of preactivation One of the earliest preactivation-based glycosylation reactions

• [18]. This protocol is found to be applicable to a wide range of glycosyl-donor types including thioglycosides, glycosyl sulfoxides, glycosyl hemiacetals, selenoglycosides, and 2-pyridyl glycosides. The newly formed oligosaccharide intermediate could be directly subjected to another round of

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• investigation of different cyclic and acyclic sulfoxides 29, they could show that the diastereoselectivity of this reaction can be clearly improved by using the chiral cinchona alkaloid-based ammonium salt A8 compared to the use of achiral tetraalkylammonium salt-based PTCs [127][128][129]. In 2013, Maruoka’s

Phenylsilane as an effective desulfinylation reagent

• Wanda H. Midura,
• Aneta Rzewnicka and
• Jerzy A. Krysiak

Beilstein J. Org. Chem. 2017, 13, 1513–1517, doi:10.3762/bjoc.13.150

• -sulfinylcarboxylates 9 and 10 with phenylsilane evidenced that the desulfinylation process occurred also in the case of acyclic sulfoxides (Scheme 3). α-Sulfinylphenylacetate 9 was formed as a mixture of diastereomers difficult to separate. This mixture, without separation, was subjected to the reaction with

• the reaction strongly depends on the character of the ketone. Different behaviour of cyclopropylphosphonates in the reaction with phenylsilane. Synthesis and desulfinylation of 4. Reaction of acyclic sulfoxides with phenylsilane. Reagents and conditions: (a) BuLi, THF, −70 °C, p-TolS(O)Men; (b) PhSiH3

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

• Adesh Kumar Singh,
• Varsha Tiwari,
• Kunj Bihari Mishra,
• Surabhi Gupta and
• Jeyakumar Kandasamy

Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113

• thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably

• , oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide. Keywords: monosaccharides; oxidation; sulfones; sulfoxides; thioglycosides; urea–hydrogen peroxide; Introduction Organosulfur compounds such as sulfides, sulfoxides and sulfones are useful intermediates

• role in carbohydrate synthesis. Thioglycosides, glycosyl sulfoxides and sulfones have been widely used as glycosyl donors in oligosaccharide synthesis which can be activated under mild reaction conditions [5][6][7][8][9][10]. Glycosyl sulfoxide donors usually provide excellent anomeric selectivity

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• more usual strategy is the so-called “selective poisoning”, i.e., the improvement of the catalyst’s selectivity by the addition of variable, often large, amount of contaminants, either organic ligands (quinolone [65][66], phosphine [67]), carbon monoxide [68], sulfides [69], sulfoxides [70][71] defined

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• (CpRu) complexes containing tethered chiral sulfoxides were synthesized via an oxidative [3 + 2] cycloaddition reaction between an alkyne and an allylruthenium complex. Sulfoxide complex 1 containing a p-anisole moiety on its sulfoxide proved to be the most efficient and selective catalyst for the

• these chiral sulfoxides needed to be explored, preferably one that did not rely on crystallization. In 2005, the Senanayake group described a process in which (+)-norephedrine-derived oxathiazolidine 2-oxides are used as sulfinyl transfer agents in the synthesis of optically pure sulfoxides and

• addition to 8 completes the synthesis of tether precursors 9 and 10. The use of an organocuprate is essential in order to obtain good yields of the desired sulfoxides; the enantiospecificity of this organocuprate addition was checked by comparison of the optical rotation of 3 synthesized by this method

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• possibilities hardly addressed so far in TTF chemistry is the oxidation of the sulfur atoms into sulfoxides or sulfones. Indeed, only two reports deal with the oxidation of BEDT-TTF into BEDT-TTF monosulfoxides (Scheme 1), along with enantioselectivity issues [27][28]. We describe herein the synthesis

• sulfoxides [27][28], yet the same feature was already observed in other sulfoxide/sulfone series [30][31]. The central C7=C8 bond measures 1.346(6) Å, which is a typical value for a neutral donor. In the packing the donors interact laterally along the a direction, with the shortest intermolecular S···S

• very important aspect related to the interest of these chiral TTF sulfones as precursors for molecular conductors is the stability of the radical cation species. As mentioned earlier, the major drawback of the inner BEDT-TTF sulfoxides is their irreversible oxidation, as the radical cations once

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• the present study were used for oxidation reactions aimed at the preparation of the corresponding sulfoxides and sulfones. As demonstrated in a recent publication [20], polycyclic sulfones are attractive substrates for the synthesis of polycyclic hydrocarbons via thermal SO2 extrusion. In our

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene

• Laurence Burroughs,
• John Ritchie,
• Mkhethwa Ngwenya,
• Dilfaraz Khan,
• William Lewis and
• Simon Woodward

Beilstein J. Org. Chem. 2015, 11, 273–279, doi:10.3762/bjoc.11.31

• cascade approach for rapid access to tetracene sulfoxides in 2007 (Scheme 1). In 2012 Liu used a Pd-based strategy to provide 12-substituted 5-aryltetracenes [after final trapping with RB(OH)2)] [16]. Both of these reactions rely on the formation of bis-allenes 2, attained by Lin through 2,3-sigmatropic

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

• oxidant and it has been employed for the selective oxidation of sulfides to the corresponding sulfoxides, for the preparation of α-methylenecyclohexane [16] and glycosyl sulfoxides [17]. Compared to the widely used peroxy acid MCPBA, MMPP has similar chemical properties, but it is a halogen-free reagent

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• methylated β-cyclodextrin (RAMEB-CD). Additionally, the influence of the oxidation of the incorporated thioether linkages on the cloud point is investigated. The resulting hydrophilic sulfoxides show higher cloud point values for the lower critical solution temperature (LCST). A high degree of

• sulfide) containing copolymers is based on the oxidation of thioethers to more hydrophilic sulfoxides or sulfones [11][12]. The specific sulfoxidation of a polymer bound end-group, which is in the focus of our present work, has not yet been investigated. Polymeric materials exhibiting sensitivity to

• the signals of the backbone between 2.0–3.9 ppm and 0.7–2.0 ppm, respectively (see Figure 2 for polymer 9b and Supporting Information File 1, Figure S6 for 8b). Oxidation of the end-group-functionalized polymers. The selective oxidation of the thioether groups to the corresponding sulfoxides was

Carbenoid-mediated nucleophilic “hydrolysis” of 2-(dichloromethylidene)-1,1,3,3-tetramethylindane with DMSO participation, affording access to one-sidedly overcrowded ketone and bromoalkene descendants^§

• Rudolf Knorr,
• Thomas Menke,
• Johannes Freudenreich and
• Claudio Pires

Beilstein J. Org. Chem. 2014, 10, 307–315, doi:10.3762/bjoc.10.28

• -products, as obtained in the above preparation of 10 and separated from the alkaline aqueous layer, were washed with distilled water until neutral, dried over Na2SO4, and evaporated. The remaining brown solid (<977 mg) contained mainly the sulfoxides 23 and 33 (3:1) together with a little of 1,1,3,3

New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions

• Helge Klare,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2014, 10, 224–236, doi:10.3762/bjoc.10.18

• , e.g. sulfonamides [12], urea-N-sulfoxides [13], guanines [14] as well as protonated catalysts such as ammonium [15], 2-aminopyridinium [16] and guanidinium [17] motifs. Most catalysts can form two hydrogen bonds to a reactant, which further enhances their ability to activate and constrain it to a

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• stability of molecules in acidic medium. One can place this substituent next to the ever-present CF3 and the emerging OCF3 substituent [55][56][130]. In contrast, aryl trifluoromethyl sulfides are key intermediates for the preparation of trifluoromethyl sulfoxides or sulfones. Aryl trifluoromethyl sulfides

AgOTf-catalyzed one-pot reactions of 2-alkynylbenzaldoximes with α,β-unsaturated carbonyl compounds

• Qiuping Ding,
• Dan Wang,
• Puying Luo,
• Meiling Liu,
• Shouzhi Pu and
• Liyun Zhou

Beilstein J. Org. Chem. 2013, 9, 1949–1956, doi:10.3762/bjoc.9.231

• regioselective alkylation of isoquinoline N-oxide and its derivatives with sulfoxides for the synthesis of 1-alkylated isoquinolines [40]. We also reported the synthesis of 1-arylated 1,3-disubstituted isoquinoline N-oxides in a one-pot reaction characterized by a Ag-catalyzed intramolecular addition cyclization

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• -substituted alkynes, such as alkynyl sulfones, sulfoxides, or sulfoximines as electron-deficient alkynes. Xie reported a copper-catalyzed carbomagnesiation of alkynyl sulfone to give the corresponding alkenylmagnesium intermediates (Scheme 2) [39][40]. Interestingly, the stereochemistry of the products was

• reagents can be used, irrespective of the identity of the organic groups, preparative protocols, and accompanying functional groups (Table 1). Similarly, Xie reported ethyl- or methylzincation of alkynyl sulfones [42] and Tanaka reported carbozincation of alkynyl sulfoxides [43][44]. Marek discovered

• efficient methods for the stereoselective synthesis of multisubstituted allylic zinc intermediates 1f from alkynyl sulfoxides with organomagnesium or -zinc reagents (Scheme 3) [45][46]. It is noteworthy that they applied their chemistry to the preparation of various allylic metals [24][25][47][48][49][50

Stereoselective synthesis of tetrasubstituted alkenes via a sequential carbocupration and a new sulfur–lithium exchange

• Andreas Unsinn,
• Cora Dunst and
• Paul Knochel

Beilstein J. Org. Chem. 2012, 8, 2202–2206, doi:10.3762/bjoc.8.248

• thioether 4. Extensive experimentation showed that thioethers 4 do not undergo Ni- or Pd-catalyzed cross couplings leading to products of type 5 (R = Me, Ph) [15][16]. Thus, we designed a new sulfur–lithium exchange (Scheme 1). Sulfur–lithium exchanges proceed only readily with sulfoxides [17][18][19] and

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• ]. Planar chiral 1,2-disubstituted ferrocene derivatives are usually synthesized by using diastereoselective ortho-lithiation of monosubstituted ferrocenes with an appropriate chiral ortho-directing substituent such as chiral amines, sulfoxides, and oxazolines [3]. However, this method suffers from low atom

Binding of group 15 and group 16 oxides by a concave host containing an isophthalamide unit

• Jens Eckelmann,
• Vittorio Saggiomo,
• Svenja Fischmann and
• Ulrich Lüning

Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2

• the magnitude of the CIS need not be correlated with the binding constants. However, when sulfoxides were added as neutral guests, the relative binding of these guests by 1 and 2 showed drastic differences. Dimethyl sulfoxide (DMSO), methylphenyl sulfoxide (MPSO) and diphenyl sulfoxides (DPSO) induced

• sulfoxides were chosen as guests, namely pyridine-N-oxide (PyNO) [18][19] and triphenylphosphine oxide (TPPO). PyNO showed the same behaviour as DMSO, i.e., large CIS for concave host 1, and small CIS for the linear compound (Figure 2, PyNO, endo-CH, 0.34 ppm for 1 and 0.14 ppm for 2). In contrast, with TPPO

Synthesis and oxidation of some azole-containing thioethers

• Andrei S. Potapov,
• Nina P. Chernova,
• Vladimir D. Ogorodnikov,
• Tatiana V. Petrenko and
• Andrei I. Khlebnikov

Beilstein J. Org. Chem. 2011, 7, 1526–1532, doi:10.3762/bjoc.7.179

• through its conversion to sulfoxide or sulfone derivatives. In this report we present the synthesis of pyrazole and benzotriazole thioether ligands and their oxidation to the corresponding sulfoxides and sulfones. Results and Discussion 1-(2-Hydroxyethyl)-3,5-dimethylpyrazole (1), the starting compound

• oxidation reactions. Oxidation of thioethers to sulfoxides and sulfones can be achieved by using different oxidants and catalysts [15], hydrogen peroxide being the most versatile and green among them [16]. Despite the simplicity of their preparation and potentially useful properties, azole-containing

• sulfoxides and sulfones are not described in the literature. The action of one mole of hydrogen peroxide on thioether 3 in acetic acid at room temperature for 2.5 h selectively gives sulfoxide 6 (85% yield, Scheme 3). Raising the temperature to the boiling point of acetic acid (118 °C) and using an excess of

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• classes of organic sulfur compounds, with chirality residing at sulfur, at carbon, or at both [2][3][4][5][6][7][8]. This field of asymmetric organosulfur chemistry is particularly well developed in connection with sulfur(IV) and sulfur(VI) species with chirality at sulfur – namely sulfoxides, sulfinates

• , sulfimines and sulfilimines [9]. Chiral sulfoxides and sulfonium ylids have themselves been extensively used as tools for asymmetric synthesis [3]. With regard to chiral sulfur(II) compounds – namely thiols and thioethers (sulfides) with chirality at carbon – methods available for their asymmetric

The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes

• Bryan Ringstrand,
• Martin Oltmanns,
• Jeffrey A. Batt,
• Aleksandra Jankowiak,
• Richard P. Denicola and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49

• been used as structural elements of liquid crystals [1][2][3][4][5][6] as well as antithrombotic and neuroprotectant agents [7][8]. Some thianes IV are found in petroleum distillates [9] and several have been used for the preparation of sulfones [7][10][11], sulfoxides [11][12], and sulfonium