- Solvent-mediated switching between oxidative addition and addition-oxidation: Access to β-hydroxysulfides and β-arylsulfones by the addition of thiols to olefins in the presence of Oxone
-
The reaction between aryl olefins and thiols in the presence of Oxone in toluene-water (9:1, v/v) affords β-hydroxy-2-arylethyl aryl sulfides smoothly by the interception of intermediary thiyl radicals with aryl olefins; the former are generated by the ox
- Moorthy, Jarugu Narasimha,Payra, Soumen,Yadav, Navin
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p. 582 - 591
(2022/01/22)
-
- Synthesis and application of Cu(II) immobilized MCM-41 based solid Lewis acid catalyst for aminolysis reaction under solvent-free condition
-
In this paper, a Cu(II) immobilized periodic mesoporous organosilica (PMOs) was synthesized and used as a reusable solid Lewis acid catalyst for the aminolysis of epoxides under solvent-free conditions. An amide-based ligand, L-propylsilyl (1) having a specific binding pocket was prepared and fabricated on mesoporous MCM-41 to produce mesoporous organosilica L-propylsilyl@MCM-41 (2). Further, it has been utilized for anchoring Cu(II) ions under controlled reaction conditions to yield solid Lewis acid catalyst Cu(II)-L-propylsilyl@MCM-41 (3). The synthesized catalyst 3 exhibits significantly higher catalytic activity for aminolysis compared to hitherto known solid Lewis acid catalysts. An extensive range of β-amino alcohols with high regio and stereoselectivity were prepared by using catalyst 3. The catalyst was recovered easily and reused eight times without any loss in its catalytic activity. Furthermore, the synthesis of clinically significant propranolol (β-blocker) from α- naphthyl glycidyl ether was attained successfully using catalyst 3 in a very decent yield.
- Chaudhary, Garima,Gupta, Neha,Singh, Amit Pratap
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supporting information
(2021/07/22)
-
- Competition Between Cα-S and Cα-Cβ Bond Cleavage in β-Hydroxysulfoxides Cation Radicals Generated by Photoinduced Electron Transfer?
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A kinetic and product study of the 3-cyano-N-methyl-quinolinium photoinduced monoelectronic oxidation of a series of β-hydroxysulfoxides has been carried out to investigate the competition between Cα-S and Cα-Cβ bond cleavage within the corresponding cation radicals. Laser flash photolysis experiments unequivocally established the formation of sulfoxide cation radicals showing their absorption band (λmax ≈ 520?nm) and that of 3-CN-NMQ? (λmax ≈ 390?nm). Steady-state photolysis experiments suggest that, in contrast to what previously observed for alkyl phenyl sulfoxide cation radicals that exclusively undergo Cα-S bond cleavage, the presence of a β-hydroxy group makes, in some cases, the Cα-Cβ scission competitive. The factors governing this competition seem to depend on the relative stability of the fragments formed from the two bond scissions. Substitution of the β-OH group with -OMe did not dramatically change the reactivity pattern of the cation radicals thus suggesting that the observed favorable effect of the hydroxy group on the Cα-Cβ bond cleavage mainly resides on its capability to stabilize the carbocation formed upon this scission.
- Lapi, Andrea,D'Alfonso, Claudio,Del Giacco, Tiziana,Lanzalunga, Osvaldo
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p. 1310 - 1321
(2021/06/07)
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- PhB(OH)2-Promoted Electrochemical Sulfuration-Formyloxylation of Styrenes and Selectfluor-Mediated Oxidation-Olefination
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We report a PhB(OH)2-promoted electrochemical sulfuration-formyloxylation reaction of styrenes employing commercially available thiophenols/thiols as thiolating agents. Specifically, metal catalysts and external chemical oxidants are not needed in the reaction for the formation of β-formyloxy sulfides, and these sulfides can be further converted to (E)-vinyl sulfones via the Selectfluor-mediated oxidation-olefination. Notably, on the basis of this electrochemical oxidation strategy, β-hydroxy sulfide, β-formyloxy sulfoxide, β-formyloxy sulfone, and (E)-vinyl sulfoxide can also be easily prepared.
- Zhao, Yulei,Guo, Xuqiang,Li, Shuai,Fan, Yuhang,Sun, Xuejun,Tian, Laijin
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supporting information
p. 9140 - 9145
(2021/11/30)
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- Air-Induced Disulfenylation of Alkenes: Facile Synthesis of Vicinal Dithioethers
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A novel disulfenylation of alkenes with thiophenols and their corresponding disulfides by using air as the oxidant has been achieved. This transformation provides a facile and practical protocol for the synthesis of vicinal dithioethers under mild conditions.
- Chen, Danyao,Chen, Qian,Huang, Yuanting,Ou, Yingcong,Yan, Y.,Yu, Guodian
-
-
- Gem-Heterosubstituted (stannyl)methylsilanes as synthetic equivalents of functionalized α-stannyl(methyl) anions
-
α-Heterosubstituted silyl derivatives, such as phenylthio-, phenylseleno- and benzotriazolyl-stannyl silanes, react with aldehydes under tetra-n-butylammonium fluoride (TBAF) catalysis, leading to α-substituted-βhydroxy stannanes, able to behave as precursors of Z- and E-olefins, generated by deoxystannylation. This reactivity shows the capability of such heterosubstituted silanes to act as masked carbanions through a mild functionalization of the carbon-silicon bond.
- Tanini, Damiano,Nocentini, Tiziano,Capperucci, Antonella
-
-
- Enantioselective, Lewis Base-Catalyzed Carbosulfenylation of Alkenylboronates by 1,2-Boronate Migration
-
A catalytic, enantioselective method for the preparation of chiral, non-racemic, alkylboronic esters bearing two vicinal stereogenic centers is described. The reaction proceeds via a 1,2-migration of a zwitterionic thiiranium-boronate complex to give excl
- Tao, Zhonglin,Robb, Kevin A.,Panger, Jesse L.,Denmark, Scott E.
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supporting information
p. 15621 - 15625
(2018/11/23)
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- Aerial dioxygen activation: Vs. thiol-ene click reaction within a system
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Markovnikov or anti-Markovnikov selective thiol-ene click (TEC) reactions and the synthesis of β-hydroxysulfides via aerial dioxygen activation are prevalent C-S bond forming reactions of styrenes and thiophenols. Herein, by choosing appropriate environme
- Choudhuri, Khokan,Mandal, Arkalekha,Mal, Prasenjit
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supporting information
p. 3759 - 3762
(2018/04/16)
-
- Iodine-catalysed regioselective synthesis of β-hydroxysulfides
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A metal-free, and environment benign iodine-catalysed protocol has been developed for the regioselective synthesis of β-hydroxysulfides in good to excellent yields from easily accessible styrenes and thiophenols. The reaction involves single step C[sbnd]S and C[sbnd]O bonds construction.
- Tehri, Piyush,Aegurula, Balakrishna,Peddinti, Rama Krishna
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supporting information
p. 2062 - 2065
(2017/05/04)
-
- Biodegradable choline hydroxide promoted environmentally benign thiolysis of epoxides
-
An environmentally benign and rapid thiolysis of epoxides using a biodegradable, choline-based task-specific ionic liquid has been developed. The ring opening reaction of aryl and alkyl epoxides proceeded rapidly and afforded the corresponding β-hydroxysulfides in high yields with excellent regioselectivity. The protocol has the advantages of easy work-up, short reaction times, high yields, and a biodegradable catalyst.
- Azizi, Najmedin,Edrisi, Mahtab
-
supporting information
p. 525 - 528
(2016/01/20)
-
- Catalyst-Free Difunctionalization of Activated Alkenes in Water: Efficient Synthesis of β-Keto Sulfides and Sulfones
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Difunctionalization of activated alkenes, a powerful strategy in chemical synthesis, has been accomplished for direct synthesis of a series of β-keto sulfides and β-keto sulfones. The transformation, mediated by O2, proceeds smoothly in water and without any catalyst. Prominent advantages of this method include mild reaction conditions, purification simplicity, and gram-scale synthesis, underlining the practical utility of this methodology.
- Wang, Huamin,Wang, Guangyu,Lu, Qingquan,Chiang, Chien-Wei,Peng, Pan,Zhou, Jiufu,Lei, Aiwen
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supporting information
p. 14489 - 14493
(2016/10/03)
-
- Synthesis of 1,1-diarylethylenes
-
A facile route toward 1,1-diarylethylenes 6 has been developed in good yields via mCPBA-promoted oxidation of β-hydroxysulfides 2, BF3·OEt2-mediated Friedel-Crafts reaction of the resulting β-hydroxysulfoxides 3 with oxygenated benze
- Chang, Meng-Yang,Huang, Yi-Hsuan,Wang, Heui-Sin
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p. 3022 - 3031
(2016/05/19)
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- Acid-Catalyzed Oxidative Addition of Thiols to Olefins and Alkynes for a One-Pot Entry to Sulfoxides
-
An oxidative variant of the thiol-ene reaction has been developed, achieving the direct addition of thiols to olefins to form sulfoxides. The reaction uses tert-butyl hydroperoxide as oxidant and methanesulfonic acid as catalyst. The latter is believed to catalyze the oxidation of the intermediate sulfide to the sulfoxide. No special precautions are necessary to exclude oxygen, yet the products are formed without oxidation at the β-position. Styrenes, acrylic acid derivatives, alkynes, and thiophenols gave the highest yields, while aliphatic olefins and thiols were less effective.
- Yue, Hui-Lan,Klussmann, Martin
-
supporting information
p. 2505 - 2509
(2016/10/24)
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- Air oxidative radical hydroxysulfurization of styrenes leading to β-hydroxysulfides
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Air oxidative radical hydroxysulfurization of styrenes initiated by 0.5 mol % of tert-butyl hydroperoxide with arylthiols is described, and a new type of difunctionalization of alkenes was achieved.
- Zhou, Shao-Fang,Pan, Xiangqiang,Zhou, Zhi-Hao,Shoberu, Adedamola,Zou, Jian-Ping
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p. 3682 - 3687
(2015/04/14)
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- NaI-Mediated Acetamidosulphenylation of Alkenes with Nitriles as the Nucleophiles: A Direct Access to Acetamidosulfides
-
An example of a transition-metal-free, direct, and efficient acetamidosulphenylation reaction of alkenes using nitriles as the nucleophiles via a radical process is presented. This reaction shows a broad substrate scope and high regioselectivity and provides straightforward access to acetamidosulfide derivatives in moderate to high yields.
- Zheng, Yang,He, Yue,Rong, Guangwei,Zhang, Xiaolu,Weng, Yuecheng,Dong, Kuiyong,Xu, Xinfang,Mao, Jincheng
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supporting information
p. 5444 - 5447
(2015/11/18)
-
- Rapid, benign, and additive-free thiolysis of epoxides under ultrasonic/aqueous conditions
-
An environmentally friendly and efficient procedure is developed for ring opening of various epoxides with thiols under non-thermal conditions. Reactions take place by ultrasonic irradiation of the two reactants suspended in an additive-free aqueous mediu
- Mojtahedi, Mohammad M.,Khalili, Sajad
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p. 431 - 437
(2014/06/10)
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- Aerobic oxysulfonylation of alkenes using thiophenols: An efficient one-pot route to β-ketosulfones
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We have developed a highly efficient synthetic route to β-ketosulfones via AgNO3 catalyzed oxysulfonylation of alkenes using thiophenols in the presence of air (O2) and K2S2O8 as eco-friendly oxidants. Thiophenols have been used as sulfonylation precursors for the first time in a dioxygen activation based radical process. Moreover, the protocol also offers a new and convenient method for the synthesis of β-hydroxysulfides at room temperature without the use of any initiator. This journal is
- Singh, Atul K.,Chawla, Ruchi,Keshari, Twinkle,Yadav, Vinod K.,Yadav, Lal Dhar S.
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supporting information
p. 8550 - 8554
(2014/12/10)
-
- In situ slow release of isocyanates: Synthesis and organocatalytic application of N-acylureas
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A novel, efficient, and operationally simple one-pot synthesis of both, symmetrical and unsymmetrical N-acylureas from carboxamides and in situ generated isocyanates (from N,N-dibromo-p-toluenesulfonamide) in the presence of a mild base at rt is reported. The protocol avoids the tedious isolation and purification steps of hazardous isocyanates. The first application of these acylureas to the catalysis through hydrogen bonding is also demonstrated.
- Singh, Atul K.,Chawla, Ruchi,Yadav, Lal Dhar S.
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p. 5099 - 5102
(2013/09/02)
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- Amberlyst-15: An efficient heterogeneous reusable catalyst for selective anti-Markovnikov addition of thiols to alkenes/alkynes and for thiolysis of epoxides
-
The anti-Markovnikov addition of thiols to alkenes/alkynes and thiolysis of epoxides is described using Amberlyst-15 as a selective, commercially available, inexpensive and reusable catalyst. The products like diorganyl sulphides, β-hydroxy sulphides and phenyl(styryl)sulfanes were obtained in good to excellent yields in short reaction time and with high regio-selectivity. The catalyst was reused up to five consecutive recycles without any loss in its catalytic activity. The developed methodology is a metal free protocol for C-S bond formation reaction with high atom economy.
- Lanke, Satish R.,Bhanage, Bhalchandra M.
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- " On-water " thiolysis of epoxides promoted by PhSZnBr
-
The synthesis of a new bench-stable and odorless zinc thiolate is here reported. The thiolysis of epoxides effected using this reagent showed a considerable rate acceleration of the reaction when effected in "on-water" conditions. In addition, the reactio
- Propersi, Simona,Tidei, Caterina,Bagnoli, Luana,Marini, Francesca,Testaferri, Lorenzo,Santi, Claudio
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p. 671 - 676
(2014/01/06)
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- Tandem base-free synthesis of β-hydroxy sulphides under ultrasound irradiation
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Rongalite promotes cleavage of diaryl disulphides generating the corresponding thiolate species in situ which then undergo facile ring-opening of epoxides in a regioselective manner under ultrasound irradiation, affording β-hydroxy sulphides in good to ex
- Lv, Guang-Shu,Duan, Fu-Jun,Ding, Jin-Chang,Cheng, Tian-Xing,Gao, Wen-Xia,Chen, Jiu-Xi,Wu, Hua-Yue
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p. 1057 - 1062
(2013/03/13)
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- Highly selective activation of vinyl C-S bonds over aryl C-S bonds in the Pd-catalyzed coupling of (E)-(β-trifluoromethyl)vinyldiphenylsulfonium salts: Preparation of trifluoromethylated alkenes and dienes
-
We describe the Suzuki coupling reaction of (E)-(β-trifluoromethyl) vinyldiphenylsulfonium salts with arylboronic acid. The highly efficient and selective reaction provides a useful and mild method for the synthesis of trifluoromethylated alkenes and dienes. Subsequent DFT studies showed that the oxidative addition transition state of the vinyl C-S bond is much more favorable (11.7 kcal mol-1) than that of the aryl C-S bond. Copyright
- Lin, Hao,Dong, Xicheng,Li, Yuxue,Shen, Qilong,Lu, Long
-
supporting information; experimental part
p. 4675 - 4679
(2012/10/08)
-
- Synthesis of optically active β-aryloxy alcohols and β-arylthiol alcohols via asymmetric transfer hydrogenation reaction
-
A series of optically active β-aryloxy alcohols and β-arylthiol alcohols were synthesized directly by asymmetric transfer hydrogenation of the corresponding β-carbonyl ethers or β-carbonyl sulfides in excellent yields (up to 99%) and excellent enantiosele
- Xu, Zhou,Yin, Wei,Wu, Nan,Shi, Jingjing,Liu, Ting,Wan, Yu,Wu, Hui
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experimental part
p. 737 - 742
(2012/06/01)
-
- JandaJel as a polymeric support to improve the catalytic efficiency of immobilized-1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) under solvent-free conditions
-
JandaJel, with its greater spacing between the linear polymeric chains compared to that of polystyrene matrices, is a very efficient support for improving the catalytic efficiency of TBD under SolFC. The Royal Society of Chemistry.
- Lanari, Daniela,Ballini, Roberto,Bonollo, Simona,Palmieri, Alessandro,Pizzo, Ferdinando,Vaccaro, Luigi
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supporting information; experimental part
p. 3181 - 3186
(2011/12/04)
-
- Efficient synthesis of-Hydroxy sulfides and-Hydroxy sulfoxides catalyzed by Cu/MgO under solvent-free conditions
-
Regio-, stereo-, and chemoselective ring opening of epoxides with thiols using Cu/MgO as a heterogeneous catalyst has efficiently been carried out to produce the corresponding β-hydroxy sulfides in excellent yields at room temperature under solvent-free c
- Das, Biswanath,Balasubramanyam, Penagaluri,Krishnaiah, Maddeboina,Veeranjaneyulu, Boyapati,Sudhakar, Dega
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experimental part
p. 2113 - 2121
(2010/08/13)
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- LiOH-catalyzed simple ring opening of epoxides under solvent-free conditions
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LiOH has been found to be a very simple and selective catalyst for the rapid and mild synthesis of β-hydroxy sulfides and β-hydroxyl nitriles by ring opening of epoxides with aromatic, aliphatic, and heterocyclic thiols and trimethylsilyl cyanide at room temperature under solvent free conditions. All the reactions proceeded satisfactorily in short times and afforded the corresponding products in good to excellent yields with high regioselectivity and chemoselectivity under mild reaction conditions. Copyright Taylor & Francis Group, LLC.
- Azizi, Najmedin,Khajeh-Amiri, Alireza,Ghafuri, Hossein,Bolourtchian, Mohammad
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scheme or table
p. 1550 - 1557
(2010/09/06)
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- Highly stereoselective preparation of chiral α-Substituted sulfides from α-Chloro sulfides via 1,2-asymmetric induction
-
A C-S stereogenic center is created with efficient stereocontrol by 1,2-asymmetric induction due to a vicinal C-O stereogenic center. Propargylic, allylic, and alkyl sulfides are readily prepared in good yield and stereoselectivity from α-chloro sulfides. The allylic sulfide have been converted to the corresponding sulfoxide/sulfilimine/sulfur ylide and subjected to [2,3]-sigmatropic rearrangement. The efficient 1,3-chirality transfer observed in this reaction eventually results in a net 1,4-chirality transfer. Georg Thieme Verlag Stuttgart.
- Raghavan, Sadagopan,Kumar, V. Vinoth,Chowhan, L. Raju
-
body text
p. 1807 - 1810
(2010/10/03)
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- Rongalite promoted highly regioselective synthesis of β-hydroxy sulfides by ring opening of epoxides with disulfides
-
Rongalite promotes cleavage of disulfides generating thiolate anions that then undergo facile ring opening of epoxides in the presence of K2CO3 to afford α-addition products 3 with good to excellent yields. The important f
- Guo, Wenxue,Chen, Jiuxi,Wu, Dengze,Ding, Jinchang,Chen, Fan,Wu, Huayue
-
experimental part
p. 5240 - 5243
(2009/11/30)
-
- One-pot synthesis of β-amino/β-hydroxy selenides and sulfides from aziridines and epoxides
-
Diaryl disulfides and diselenides undergo facile cleavage on treatment with rongalite (sodium hydroxymethanesulfinate) to generate the corresponding thiolate and selenolate species in situ, which effect the ring opening of aziridines and epoxides in a reg
- Ganesh, Venkataraman,Chandrasekaran, Srinivasan
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experimental part
p. 3267 - 3278
(2010/02/27)
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- Cyanuric chloride: An efficient catalyst for ring opening of epoxides with thiols under solvent-free conditions
-
2,4,6-Trichloro-1,3,5-triazine-catalyzed convenient and efficient ring opening of epoxides with thiols under solvent-free conditions is described. Short reaction time, mild reaction conditions, inexpensive and readily available catalyst, and excellent yie
- Bandgar, Babasaheb P.,Joshi, Neeta S.,Kamble, Vinod T.,Sawant, Sanjay S.
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p. 231 - 234
(2008/09/18)
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- Additive-free thiolysis of epoxides in water: A green and efficient regioselective pathway to β-hydroxy sulfides
-
Room-temperature ring opening of various epoxides with aromatic thiols was carried out in water in the absence of any Lewis acid or additive. High yields of β-hydroxy sulfides with excellent regioselectivity were obtained under very environmentally friend
- Abaee, Saeed M.,Mojtahedi, Mohammad M.,Abbasi, Hassan,Fatemi, Ensieh R.
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p. 282 - 289
(2008/03/17)
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- A general and efficient method for the selective synthesis of β-hydroxy sulfides and β-hydroxy sulfoxides catalyzed by gallium(III) triflate
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(Chemical Equation Presented) Gallium(III) triflate-catalyzed ring opening of epoxides affords β-hydroxy sulfides with high regioselectivity and chemoselectivity in high yields (84-97%) under solvent-free conditions. Additionally, a simple, efficient, and environmentally benign one-pot procedure for the synthesis of β-hydroxy sulfoxides in sole water has been developed for the first time. The process, promoted by a H2O 2-Ga(OTf)3 system, affords β-hydroxy sulfoxides in high yields (81-94%) and high chemoselectivity without any detectable overoxidation to β-hydroxy sulfones. The catalyst could be recovered easily after the reactions and reused without evident loss of activity.
- Su, Weike,Chen, Jiuxi,Wu, Huayue,Jin, Can
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p. 4524 - 4527
(2008/02/05)
-
- Ionic liquid promoted regio- and stereo-selective thiolysis of epoxides-A simple and green approach to β-hydroxy- and β-keto sulfides
-
A variety of epoxides underwent facile cleavage by thiols under the catalysis of 1-methyl-3-butylimidazolium bromide, [bmIm]Br, to produce the corresponding β-hydroxy sulfides with high regio- and stereo-selectivity. On the other hand, a specially designed basic ionic liquid, [bmIm]OH, efficiently catalyzes the thiolysis of ,β-epoxy ketones providing β-keto sulfides through simultaneous retro-aldol cleavages. The reactions are clean, high yielding, and do not require any organic solvent. The catalyst is also recycled. CSIRO 2007.
- Ranu, Brindaban C.,Mandal, Tanmay,Banerjee, Subhash,Dey, Suvendu S.
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p. 278 - 283
(2008/02/11)
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- Stereo- and regioselective thiolysis of 1,2-epoxides in water
-
A simple, efficient, stereoselective, and highly regioselective procedure for the synthesis of β-hydroxy sulfides by thiolysis of various 1,2-epoxides in water as a solvent, using no catalyst and under very mild conditions, is described. Copyright Taylor
- Movassagh, Barahman,Soleiman-Beigi, Mohammad
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p. 3239 - 3244
(2008/02/12)
-
- Polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene as an efficient and reusable catalyst for the thiolysis of 1,2-epoxides under solvent-free conditions
-
Polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene (PS-TBD) is an effective basic catalyst for the thiolysis of the 1,2-epoxides 1a-e by the aryl- and alkyl-substituted thiols 2A-E under solvent-free conditions while its activity is remarkably redu
- Fringuelli, Francesco,Pizzo, Ferdinando,Vittoriani, Carla,Vaccaro, Luigi
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p. 1231 - 1236
(2007/10/03)
-
- Hydrophobic amplification of noncovalent organocatalysis
-
The effects of hydrogen-bonding organocatalysts and water for the acceleration of epoxide openings with a variety of nucleophiles are additive and lead to excellent yields of the catalyzed reactions in water. The Royal Society of Chemistry 2006.
- Kleiner, Christian M.,Schreiner, Peter R.
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p. 4315 - 4317
(2007/10/03)
-
- Solvent-free thiolysis of epoxides under lithium perchlorate catalysis
-
Solvent-free ring opening of 1,2-epoxides with thiols using catalytic amounts of lithium perchlorate affords high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the sterically less hindered side of the epoxides.
- Mojtahedi, Mohammad M.,Abassi, Hassan,Saeed Abaee,Mohebali, Bahareh
-
p. 455 - 458
(2007/10/03)
-
- Synthesis of β-hydroxysulfides from alkenes under supramolecular catalysis in the presence of β-cyclodextrin in water
-
An environmentally benign and highly efficient procedure has been developed for the direct one-pot synthesis of β-hydroxysulfides in good yields under neutral conditions from alkenes and thiophenols in the presence of aerial oxygen using β-cyclodextrin in
- Surendra,Krishnaveni, N. Srilakshmi,Sridhar,Rao, K. Rama
-
p. 5819 - 5821
(2007/10/03)
-
- A general strategy for stereoselective glycosylations
-
The principal challenge that the synthesis of oligosaccharides of biological importance presents is the development of a general approach for the stereoselective introduction of a glycosidic linkage. It is shown here that a (1S)-phenyl-2-(phenylsulfanyl)e
- Kim, Jin-Hwan,Yang, Hai,Park, Jin,Boons, Geert-Jan
-
p. 12090 - 12097
(2007/10/03)
-
- Steady-state and laser flash photolysis study of the carbon-carbon bond fragmentation reactions of 2-arylsulfanyl alcohol radical cations
-
The N-methylquinolinium tetrafluoroborate (NMQ+)-sensitized photolysis of the erythro-1,2-diphenyl-2-arylsulfanylethanols 1-3 (1, aryl = phenyl; 2, aryl = 4-methylphenyl; 3, aryl = 3-chlorophenyl) has been investigated in MeCN, under laser flash and steady-state photolysis. Under laser irradiation, the formation of sulfide radical cations of 1-3, in the monomeric (λmax = 520-540 nm) and dimeric form (λmax = 720-800 nm), was observed within the laser pulse. The radical cations decayed by first-order kinetics, and under nitrogen, the formation of ArSCH .Ph (λmax = 350-360 nm) was clearly observed. This indicates that the decay of the radical cation is due to a fragmentation process involving the heterolytic C-C bond cleavage, a conclusion fully confirmed by steady-state photolysis experiments (formation of benzaldehyde and the dimer of the α-arylsulfanyl carbon radical). Whereas the fragmentation rate decreases as the C-C bond dissociation energy (BDE) increases, no rate change was observed by the replacement of OH by OD in the sulfide radical cation (kOH/kOD = 1). This suggests a transition state structure with partial C-C bond cleavage where the main effect of the OH group is the stabilization of the transition state by hydrogen bonding with the solvent. The fragmentation rate of 2-hydroxy sulfanyl radical cations turned out to be significantly slower than that of nitrogen analogues of comparable reduction potential, probably due to a more efficient overlap between the SOMO in the heteroatom and the C-C bond σ-orbital in the second case. The fragmentation rates of 1+.-3+. were found to increase by addition of a pyridine, and plots of kbase against base strength were linear, allowing calculation of the β Bronsted values, which were found to increase as the reduction potential of the radical cation decreases, β = 0.21 (3+.), 0.34 (1+.), and 0.48 (2 +.). The reactions of 1+. exhibit a deuterium kinetic isotope effect with values that increase as the base strength increases: k OH/kOD = 1.3 (pyridine), 1.9 (4-ethylpyridine), and 2.3 (4-methoxypyridine). This finding and the observation that with the above three bases the rate decreases in the order 3+. > 1+. > 2+., i.e., as the C-C BDE increases, suggest that C-C and O-H bond cleavages are concerted but not synchronous, with the role of OH bond breaking increasing as the base becomes stronger (variable transition state). It is probable that, with the much stronger base, 4-(dimethylamino)pyridine, a change to a stepwise mechanism may occur where the slow step is the formation of a radical zwitterion that then rapidly fragmentates to products.
- Baciocchi, Enrico,Del Giacco, Tiziana,Elisei, Fausto,Gerini, Maria Francesca,Lapi, Andrea,Liberali, Prisca,Uzzoli, Barbara
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p. 8323 - 8330
(2007/10/03)
-
- Regioselective reaction of epoxides with disulfides using Zn/AlCl 3 system: A simple synthesis of β-hydroxy sulfides
-
Epoxides are regioselectively cleaved by zinc thiolate intermediate, generated from disulfides in the presence of Zn/AlCl3 system, to afford high yields of the corresponding β-hydroxy sulfides.
- Movassagh,Sobhani,Kheirdoush,Fadaei
-
p. 3103 - 3108
(2007/10/03)
-
- Efficient ring-opening reaction of epoxides and aziridines promoted by tributylphosphine in water
-
Tributylphosphine was found to be an effective promoting reagent for the ring-opening reaction of various epoxides and aziridines with nucleophile to produce corresponding anti-bifunctional products in moderate to excellent yields in water.
- Fan, Ren-Hua,Hou, Xue-Long
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p. 726 - 730
(2007/10/03)
-
- ZnCl2 as an Efficient Catalyst in the Thiolysis of 1,2-Epoxides by Thiophenol in Aqueous Medium
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ZnCl2 (5 mol%) is an efficient catalyst for the thiolysis of 1,2-epoxides by thiophenol in water at pH 4.0. A variety of β-hydroxy phenylsulfides were obtained in short reaction times and excellent yields. Starting from cyclohexene oxide (1), two one-pot multi-step procedures in sole water (thiolysis/oxidation with H2O2) have been realized, for the chemoselective synthesis of the corresponding β-hydroxysulfoxides 19 or for the related β-hydroxysulfone 20.
- Amantini, David,Fringuelli, Francesco,Pizzo, Ferdinando,Tortoioli, Simone,Vaccaro, Luigi
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p. 2292 - 2296
(2007/10/03)
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- Zn(II)-catalyzed thiolysis of oxiranes in water under neutral conditions
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Thiolysis of a variety of 1,2-epoxides in water at 30 °C and pH 7.0 is strongly accelerated by ZnCl2 (10 mol %) except when amino- and carboxythiophenol are used. The aqueous medium and the catalyst were recovered and reused in various runs wit
- Fringuelli, Francesco,Pizzo, Ferdinando,Tortoioli, Simone,Vaccaro, Luigi
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p. 8248 - 8251
(2007/10/03)
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- Thiolysis of 1,2-epoxides by thiophenol catalyzed under solvent-free conditions
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Thiolysis of alkyl- and aryl-1,2-epoxides was investigated under solvent-free conditions in the presence of Lewis and Br?nsted acid and base catalysts (InCl3, p-TsOH, n-Bu3P, K2CO3). Five mol% of catalyst was su
- Fringuelli, Francesco,Pizzo, Ferdinando,Tortoioli, Simone,Vaccaro, Luigi
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p. 6785 - 6787
(2007/10/03)
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- Thiolysis of Alkyl- and Aryl-1,2-epoxides in Water Catalyzed by InCl3
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The pH dependence of thiolysis of 1,2-epoxides with thiophenol in water and the influence of a Lewis acid catalyst is investigated. InCl3 showed a very high efficiency in catalyzing this process at pH 4.0. The regioselectivity of the nucleophilic attack is markedly influenced going from pH 9.0 to pH 4.0. A one-pot procedure running solely in water to prepare trans-2-(phenylsulphinyl)cyclohexan-1-ol is reported starting from epoxycyclohexane, via thiolysis reaction and oxidation with t-butyl hydroperoxide.
- Fringuelli, Francesco,Pizzo, Ferdinando,Tortoioli, Simone,Vaccaro, Luigi
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p. 379 - 384
(2007/10/03)
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- Highly efficient synthesis of chiral β-hydroxy sulfides with high enantiomeric purity via CBS-oxazaborolidine-catalyzed borane reduction
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A simple and efficient synthesis of chiral β-hydroxy p-tolylsulfides with high enantiomeric purity by CBS-oxazaborolidine-catalyzed asymmetric borane reduction of β-keto p-tolylsulfides using N-ethyl-N-isopropylaniline-borane complex as the borane carrier is reported.
- Cho, Byung Tae,Choi, Ok Kyoung,Kim, Dong Jun
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p. 697 - 703
(2007/10/03)
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- Reactions of PhSCH2Li and NCCH2Li with benzaldehyde and benzophenone: When does the mechanism change from ET to polar?
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The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of phenylthiomethyllithium (PhSCH2Li, 1) with benzaldehyde and benzophenone, and cyanomethyllithium (NCCH2Li, 2) with benzaldehyde, and the results were compared with those for other lithium reagents such as MeLi, PhLi, CH2=CHCH2Li, and CH2=C(OLi)C(CH3)3. It was previously shown that the reactions of MeLi, PhLi, and CH2=CHCH2Li proceed via a rate-determining electron transfer (ET) process whereas the reaction of lithium pinacolone enolate goes through the polar (PL) mechanism. The reaction of 1 with benzaldehyde gave no carbonyl-carbon KIE (12k/13k = 0.999 ± 0.004), similar to that measured previously for the MeLi reaction with benzophenone (12k/14k = 1.000). The effect of substituents of the aromatic ring of benzaldehyde and benzophenone on the reactivity gave very small Hammett ρ values of 0.17 ± 0.03 and 0.26 ± 0.05, respectively. These small ρ values are again similar to that observed for the reaction of MeLi. Likewise the reactions of 2 with benzaldehydes gave small KIE and the ρ value (12k/13k = 0.996 ± 0.004, p = 0.14 ± 0.02). Dehalogenation and enone-isomerization probe experiments for 2 showed no evidence for the presence of radical-ion pair of sufficient lifetime during the course of the reaction. It is concluded that the reactions of 1 and 2 with the aromatic carbonyl compounds proceed via the electron transfer-radical coupling mechanism with rate-determining ET as in the reactions of MeLi, PhLi, and CH2=CHCH2Li.
- Yamataka,Sasaki,Kuwatani,Mishima,Shimizu,Tsuno
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p. 2131 - 2135
(2007/10/03)
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- Functionalized organolithium compounds of DTBB-catalyzed sulfur-lithium exchange
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The successive reaction of β- or γ-hydroxy or amino phenyl thioethers (1,4) with butyllithium and an excess of lithium powder in the presence of a catalytic amount of DTBB in THF at - 78°C leads to the formation of the corresponding β- or γ-functionalized organolithium compounds 2 or 5, respectively, which by treatment with different electrophiles [D2O, t- BuCHO, PhCHO, Me2CO, (CH2)4CO, (CH2)5CO] at temperatures ranging between - 78°C and room temperature yields, after hydrolysis with water, the expected functionalized alcohols or amines 3 or 6, respectively, in a completely regioselective manner.
- Foubelo, Francisco,Gutiérrez, Ana,Yus, Miguel
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p. 503 - 514
(2007/10/03)
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- Novel bi- and tridentate phosphane and thioether ligands derived from chiral α-hydroxy acids
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Novel bi- and tridentate ligands with phosphane and thioether moieties have been prepared in enantiomerically pure form in good to excellent yields by substitution reactions with phosphorus and sulfur nucleophiles of easily available tosylates derived from natural chiral α-hydroxy acids.
- Christoffers, Jens,Roessler, Ulrich
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p. 1207 - 1215
(2007/10/03)
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