Co-reporter:Shan Jiang, Tai-Shan Yan, Yong-Chao Han, Li-Qian Cui, Xiao-Song Xue, and Chi Zhang
The Journal of Organic Chemistry November 17, 2017 Volume 82(Issue 22) pp:11691-11691
Publication Date(Web):June 3, 2017
DOI:10.1021/acs.joc.7b00883
We have developed an efficient method for direct formation of epoxide groups from carbon(sp2)–carbon(sp3) single bonds of β-keto esters; the reaction is mediated by the water-soluble hypervalent iodine(V) reagent AIBX (5-trimethylammonio-1,3-dioxo-1,3-dihydro-1λ5-benzo[d][1,2]iodoxol-1-ol anion). On the basis of the results of density functional theory calculations and experimental studies, we propose that the reaction proceeds by a two-stage mechanism involving dehydrogenation of the β-keto ester substrates and epoxidation of the resulting enone intermediates. The rate-limiting step is abstraction of the β′-C–H (calculated free energy of activation, 24.5 kcal/mol).
Co-reporter:Ya-Nan Duan, Zhao Zhang, and Chi Zhang
Organic Letters 2016 Volume 18(Issue 23) pp:6176-6179
Publication Date(Web):November 18, 2016
DOI:10.1021/acs.orglett.6b03209
A method is developed for the synthesis of cyclopropanes from the C(sp2)–C(sp3) single bonds of β-keto esters with activated methylene compounds under metal-free conditions in the presence of 5-trimethylammonio-1,3-dioxo-1,3-dihydro-1λ5-benzo[d][1,2]iodoxol-1-ol anion (AIBX), a recyclable water-soluble hypervalent iodine(V) reagent developed by our group. This mild, efficient method has a wide substrate scope and good functional group tolerance and is complementary to existing cyclopropanation strategies. The method can be used to construct polysubstituted ring-fused cyclopropanes and is amenable to further synthetic transformations for construction of complex biologically active molecules as well as asymmetric cyclopropanes (90% de) when a chiral ester auxiliary is used.
Co-reporter:Chi Zhang, Shan-Shan Liu, Bo Sun, and Jun Tian
Organic Letters 2015 Volume 17(Issue 16) pp:4106-4109
Publication Date(Web):August 7, 2015
DOI:10.1021/acs.orglett.5b02045
6-(3,5-Bis(trifluoromethyl)phenyl)-1H,4H-2aλ3-ioda-2,3-dioxacyclopenta[hi]indene-1,4-dione (p-BTFP-iodosodilactone, 1a) was synthesized and demonstrated to be an efficient hypervalent iodine(III) reagent for the synthesis of dipeptides from various standard amino acids, including sterically hindered amino acids, in good to high yields within 30 min in the presence of tris(4-methoxyphenyl)phosphine. In addition, the combined system of 1a/(4-MeOC6H4)3P was used to synthesize the pentapeptide leu-enkephalin in protected form. It is worth noting that 1a can be regenerated readily after reaction.
Co-reporter:Ya-Nan Duan;Li-Qian Cui;Lin-Hong Zuo
Chemistry - A European Journal 2015 Volume 21( Issue 37) pp:13052-13057
Publication Date(Web):
DOI:10.1002/chem.201502450
Abstract
We have developed a method for recyclable hypervalent-iodine-mediated direct dehydrogenative α,β′- bifunctionalization of β-ketoesters and β-diketones under metal-free conditions, which affords a straightforward way to synthesize benzo-fused 2,3-dihydrofurans. This efficient, mild method, which has a wide substrate scope and good functional-group tolerance, was used for the multistep synthesis of the protected aglycone of a naturally occurring phenolic glycoside. A mechanism involving Michael addition to an enone intermediate and subsequent oxidative cyclization is proposed.
Co-reporter:Jian Cui, Qun Jia, Ruo-Zhu Feng, Shan-Shan Liu, Tian He, and Chi Zhang
Organic Letters 2014 Volume 16(Issue 5) pp:1442-1445
Publication Date(Web):February 26, 2014
DOI:10.1021/ol500238k
A widely used Lewis acid BF3·Et2O was shown to be capable of acting as an efficient fluorinating agent in an intramolecular aminofluorination reaction of homoallylic amines to provide 3-fluoropyrrolidines mediated by a commercially available hypervalent iodine(III) reagent PhIO at room temperature. A mechanism involving a carbocation intermediate was proposed on the basis of several experimental evidence.
Co-reporter:Tian He;Wen-Chao Gao;Wei-Kun Wang
Advanced Synthesis & Catalysis 2014 Volume 356( Issue 5) pp:1113-1118
Publication Date(Web):
DOI:10.1002/adsc.201300982
Co-reporter:Wen-Chao Gao, Shan Jiang, Ruo-Lin Wang and Chi Zhang
Chemical Communications 2013 vol. 49(Issue 43) pp:4890-4892
Publication Date(Web):27 Feb 2013
DOI:10.1039/C3CC40797G
A general method for constructing both 2-acylindoles and 2-acylindolines via I2-mediated intramolecular C–N bond formation is presented, and the selective formation of either 2-acylindoles or 2-acylindolines just depends on the nitrogen protecting groups used in the same substrate skeletons.
Co-reporter:Wen-Chao Gao, Ruo-Lin Wang and Chi Zhang
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 41) pp:7123-7128
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3OB41566J
The reagent system of I2/K2CO3 could efficiently promote the oxazole synthesis from α-bromoketones and benzylamine derivatives in DMF. This method was not only suitable for 2,5-diaryl oxazole synthesis but also for 2,4,5-trisubstituted oxazole and 5-alkyl/alkenyl oxazole synthesis. Furthermore, this method was successfully applied to a one-step synthesis of a natural product halfordinol in 62% yield.
Co-reporter:Jun Yu, Shan-Shan Liu, Jian Cui, Xue-Sen Hou, and Chi Zhang
Organic Letters 2012 Volume 14(Issue 3) pp:832-835
Publication Date(Web):January 19, 2012
DOI:10.1021/ol203358f
A direct α-amination of β-dicarbonyl compounds has been achieved by using iodosobenzene (PhIO) as an oxidant and p-toluenesulfonamide (TsNH2) as an aminating reagent in the presence of a catalytic amount of perchlorate zinc hexahydrate. The present amination reaction proceeds quickly at rt (<30 min needed for most tested substrates) to provide the corresponding α-N-tosylamido β-dicarbonyl compounds in high to excellent yields.
Co-reporter:Jun Tian, Wen-Chao Gao, Dong-Mei Zhou, and Chi Zhang
Organic Letters 2012 Volume 14(Issue 12) pp:3020-3023
Publication Date(Web):June 6, 2012
DOI:10.1021/ol301085v
A hypervalent iodine(III) reagent plays a novel role as an efficient coupling reagent to promote the direct condensation between carboxylic acids and alcohols or amines to provide esters, macrocyclic lactones, amides, as well as peptides without racemization. The regeneration of iodosodilactone (1) can also be readily achieved. The intermediate acyloxyphosphonium ion C from the activation of a carboxylic acid is thought to be involved in the present esterification reaction.
Co-reporter:Li-Qian Cui, Kai Liu and Chi Zhang
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 7) pp:2258-2265
Publication Date(Web):08 Feb 2011
DOI:10.1039/C0OB00722F
Catalytic oxidation of benzylic C–H bonds could be efficiently realized using IBS as a catalyst which was generated in situ from the oxidation of sodium 2-iodobenzenesulfonate (1b) by Oxone in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydrogen sulfate, in anhydrous acetonitrile at 60 °C. Various alkylbenzenes, including toluenes and ethylbenzenes, several oxygen-containing functionalities substituted alkylbenzenes, and a cyclic benzyl ether could be efficiently oxidized. And, the same reagent system of cat. 1b/Oxone/cat. n-Bu4NHSO4 could be applied to the effective oxidation of alkanes as well.
Co-reporter:Jun Yu, Jian Cui, Xue-Sen Hou, Shan-Shan Liu, Wen-Chao Gao, Shan Jiang, Jun Tian, Chi Zhang
Tetrahedron: Asymmetry 2011 Volume 22(Issue 23) pp:2039-2055
Publication Date(Web):15 December 2011
DOI:10.1016/j.tetasy.2011.12.003
Enantiomerically pure iodoarene (S)-2 and its derivatives (S)-3 to (S)-18 with a spirobiindane scaffold have been synthesized. The evaluation of these new chiral iodoarenes as catalysts in the enantioselective α-tosyloxylation of ketones was performed using m-CPBA as a stoichiometric oxidant, and the synthetically useful α-tosyloxylated ketones were obtained in up to 58% enantiomeric excess (ee).(S)-1-Oxo-1-phenylpropan-2-yl 4-methylbenzenesulfonateC16H16O4S53% ee[α]D25=-5.2 (c 0.5, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (S)1-Oxo-1-phenylbutan-2-yl 4-methylbenzenesulfonateC17H18O4S58% ee[α]D25=-8.2 (c 0.9, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown2-Oxo-1,2-diphenylethyl 4-methylbenzenesulfonateC21H18O4S13% ee[α]D25=-33.0 (c 1.0, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown1-Cyclohexyl-1-oxopropan-2-yl 4-methylbenzenesulfonateC16H22O4S22% ee[α]D25=-7.75 (c 0.8, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown1-Oxo-1-phenylpropan-2-yl 2,4,6-triisopropylbenzenesulfonateC24H32O4S50% ee[α]D25=-4.8 (c 0.5, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: unknown
Co-reporter:Xiao-Qiang Li;Wei-Kun Wang;Yi-Xin Han
Advanced Synthesis & Catalysis 2010 Volume 352( Issue 14-15) pp:2588-2598
Publication Date(Web):
DOI:10.1002/adsc.201000318
Abstract
Benzylic primary alcohols can be directly converted into symmetrical 1,3-diarylureas or substituted benzamides via an one-pot oxidative reaction using the combined reagent of phenyliodine diacetate and sodium azide. This new reaction constitutes a step-economical way to prepare symmetric 1,3-diarylureas or substituted benzamides depending upon the substituents on the phenyl rings of starting alcohols. The sodium acetate generated in situ from the ligand exchange between phenyliodine diacetate and sodium azide plays the pivotal role in the formation of 1,3-diarylureas. In addition, it is also found that various secondary alcohols can be readily oxidized to their corresponding ketones in excellent yields using the same reagent system of phenyliodine diacetate and sodium azide. Generally, secondary alcohols are preferentially oxidized to the corresponding ketones in the presence of primary ones with the limited amounts of phenyliodine diacetate and sodium azide.
Co-reporter:Jun Yu;Jun Tian
Advanced Synthesis & Catalysis 2010 Volume 352( Issue 2-3) pp:531-546
Publication Date(Web):
DOI:10.1002/adsc.200900737
Abstract
p-Iodotoluene difluoride (p-Tol-IF2) has been found to be a general reagent for the effective introduction of various oxygen-containing functionalities including tosyloxy, mesyloxy, acetoxy, phosphoryloxy, methoxy, ethoxy and isopropoxy at the α-position of β-dicarbonyl compounds. These transformations can be readily realized by the use of the combined reagent of p-iodotoluene difluoride and various oxygen-containing nucleophilic compounds such as p-toluenesulfonic acid, methanesulfonic acid, acetic acid, diphenyl phosphate, methanol, ethanol and propan-2-ol under mild conditions, respectively. And, the in situ generated hypervalent iodine(III) species via ligand exchange between p-iodotoluene difluoride and the respective oxygen-containing nucleophiles are believed to be the real oxidizing agents in such transformations.
Co-reporter:Jun Yu;Jian Cui
European Journal of Organic Chemistry 2010 Volume 2010( Issue 36) pp:7020-7026
Publication Date(Web):
DOI:10.1002/ejoc.201000940
Abstract
Oxone has been found to be a highly efficient reagent for the introduction of a hydroxy group at the α position of a variety of β-dicarbonyl compounds in the homogeneous solvent mixture of water and 1,4-dioxane at 60 °C.
Co-reporter:Xiao-Qiang Li;Wei-Kun Wang
Advanced Synthesis & Catalysis 2009 Volume 351( Issue 14-15) pp:2342-2350
Publication Date(Web):
DOI:10.1002/adsc.200900428
Abstract
An effective synthesis of carbamoyl azides directly from primary alcohols using iodobenzene dichloride in combination with sodium azide has been developed. Moreover, the same regent combination was also efficient for the oxidation of secondary alcohols to the corresponding ketones.
Co-reporter:Jian Cui, Ya-Nan Duan, Jun Yu and Chi Zhang
Inorganic Chemistry Frontiers 2016 - vol. 3(Issue 12) pp:
Publication Date(Web):
DOI:10.1039/C6QO00405A
Co-reporter:Wen-Chao Gao, Shan Jiang, Ruo-Lin Wang and Chi Zhang
Chemical Communications 2013 - vol. 49(Issue 43) pp:NaN4892-4892
Publication Date(Web):2013/02/27
DOI:10.1039/C3CC40797G
A general method for constructing both 2-acylindoles and 2-acylindolines via I2-mediated intramolecular C–N bond formation is presented, and the selective formation of either 2-acylindoles or 2-acylindolines just depends on the nitrogen protecting groups used in the same substrate skeletons.
Co-reporter:Wen-Chao Gao, Ruo-Lin Wang and Chi Zhang
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 41) pp:NaN7128-7128
Publication Date(Web):2013/08/30
DOI:10.1039/C3OB41566J
The reagent system of I2/K2CO3 could efficiently promote the oxazole synthesis from α-bromoketones and benzylamine derivatives in DMF. This method was not only suitable for 2,5-diaryl oxazole synthesis but also for 2,4,5-trisubstituted oxazole and 5-alkyl/alkenyl oxazole synthesis. Furthermore, this method was successfully applied to a one-step synthesis of a natural product halfordinol in 62% yield.
Co-reporter:Li-Qian Cui, Kai Liu and Chi Zhang
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 7) pp:NaN2265-2265
Publication Date(Web):2011/02/08
DOI:10.1039/C0OB00722F
Catalytic oxidation of benzylic C–H bonds could be efficiently realized using IBS as a catalyst which was generated in situ from the oxidation of sodium 2-iodobenzenesulfonate (1b) by Oxone in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydrogen sulfate, in anhydrous acetonitrile at 60 °C. Various alkylbenzenes, including toluenes and ethylbenzenes, several oxygen-containing functionalities substituted alkylbenzenes, and a cyclic benzyl ether could be efficiently oxidized. And, the same reagent system of cat. 1b/Oxone/cat. n-Bu4NHSO4 could be applied to the effective oxidation of alkanes as well.