- Investigations to mechanism and applications of the glycosylation protocol employing 8-methyltosylaminoethynyl-1-naphthyl (MTEAN) glycoside donors
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Based on the capability of silyl ethers for efficient glycosylation, the new MTEAN glycosylation protocol utilizing 8-methyltosylaminoethynyl-1-naphthyl (MTEAN) glycosides as donors were extended to one-pot synthesis of nucleosides, late-stage modification of bioactive molecules, and stereoselective construction of 1,2-cis-glucosidic linkages using silyl ethers of the acceptors. Moreover, the reaction mechanism was systematically investigated by control reactions and side product characterizations, leading to the determination of a TfOH-catalyzed ynamide functionality-initiated process, which was further corroborated by identifications of the departure form of leaving group and the real catalyst.
- Li, Ming-Dong,Liao, Jin-Xi,Liu, De-Yong,Liu, Hui-Juan,Sun, Jian-Song,Zhang, Qing-Ju,Zhou, Si-Yu
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- Hydrogen bond activated glycosylation under mild conditions
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Herein, we report a new glycosylation system for the highly efficient and stereoselective formation of glycosidic bonds using glycosyl N-phenyl trifluoroacetimidate (PTFAI) donors and a charged thiourea hydrogen-bond-donor catalyst. The glycosylation prot
- Codée, Jeroen D. C.,Hu, Yongxin,Li, XinXin,Liao, Jinxi,Liu, Deyong,Nie, Qin,Sun, Jiansong,Tu, Yuanhong,Wan, Yongyong,Wang, Liming,Xiao, Ke,Yan, Hao,Zhang, Qingju
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p. 1600 - 1607
(2022/02/21)
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- 8-(Methyltosylaminoethynyl)-1-naphthyl (MTAEN) Glycosides: Potent Donors in Glycosides Synthesis
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With 8-(methyltosylaminoethynyl)-1-naphthyl (MTAEN) glycoside as donors, a novel and efficient glycosylation protocol has been established. The MTAEN glycosylation protocol exhibits the merits of shelf-stable donors, mild catalytic promotion conditions, considerably extended substrate scope encompassing both free alcohols, silylated alcohols, nucleobases, primary amides, and C-type nucleophile acceptors, and applicability to various one-pot strategies for highly efficient synthesis of oligosaccharides, such as orthogonal one-pot, single-catalyst one-pot, and acceptor reactivity-controlled one-pot strategies.
- Zhou, Si-Yu,Hu, Xin-Ping,Liu, Hui-Juan,Zhang, Qing-Ju,Liao, Jin-Xi,Tu, Yuan-Hong,Sun, Jian-Song
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supporting information
p. 653 - 657
(2022/01/20)
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- Triflic Imide-Catalyzed Glycosylation of Disarmed Glycosyl ortho-Isopropenylphenylacetates and ortho-Isopropenylbenzyl Thioglycosides
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Glycosylation reaction involving the coupling of a glycosyl donor with a glycosyl acceptor is one of the cornerstones of chemical preparation of pure glycans and glycoconjugates of biological relevance. Catalytic glycosylation of glycosyl ester donors and thioglycosides is an attractive but underexplored topic in carbohydrate chemistry. Herein, triflic imide (Tf2NH)-catalyzed glycosylation of various O-, S-, and C-nucleophiles has been achieved using disarmed glycosyl ortho-isopropenylphenylacetates (GIPPAs) and ortho-isopropenylbenzyl thioglycosides as glycosylating agents. The reactions proceed under mild conditions to give the desired glycosides in good-to-excellent yields. Of particular note, the comparable reactivity for the α-isomers and the β-ones of GIPPAs is observed. The mechanistic investigation demonstrates that the isopropenyl group is essential for the reaction and its preferential protonation triggers the reaction. This work provides another member to the arsenals of glycosyl ester and thioglycoside donors suitable for acid-catalyzed glycosylation to create various glycosidic bonds.
- Qiao, Zhi,Wang, Peng,Ni, Jingxuan,Li, Dongwei,Sun, Yao,Li, Tiantian,Li, Ming
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- Revisiting Glycosylations Using Glycosyl Fluoride by BF3·Et2O: Activation of Disarmed Glycosyl Fluorides with High Catalytic Turnover
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Catalytic glycosylations with glycosyl fluorides using BF3·Et2O are presented. Glycosylations with both armed and disarmed donors were efficiently catalyzed by 1 mol% of BF3·Et2O in a nitrogen-filled glovebox without the use of dehydrating agents. Our finding is in sharp contrast with conventional BF3·Et2O-mediated glycosylations, where excess Lewis acid and additives are required. Mechanistic studies indicated that the chemical species formed by the reaction of in situ generated HF and glass vessels are involved in the catalytic cycle.
- Manabe, Yoshiyuki,Matsumoto, Takuya,Ikinaga, Yuka,Tsutsui, Yuya,Sasaya, Shota,Kadonaga, Yuichiro,Konishi, Akihito,Yasuda, Makoto,Uto, Tomoya,Dai, Changhao,Yano, Kumpei,Shimoyama, Atsushi,Matsuda, Ayana,Fukase, Koichi
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supporting information
p. 6 - 10
(2022/01/04)
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- Ferrocenium complex aided: O-glycosylation of glycosyl halides
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A new strategy for the activation of glycosyl halide donors to be utilized in glycosylation reactions is presented, utilizing the ferrocenium (Fc) complexes [FcB(OH)2]SbF6 and FcBF4 as promoters. The scope of the new system has been investigated using glycosyl chloride and glycosyl fluoride donors in combination with common glycosyl acceptors, such as protected glucose. The corresponding glycosylation products were formed in 95 to 10% isolated yields with α/β ratios ranging from 1/1 to β only (2 to 14 h reaction time at room temperature, 40 to 100% ferrocenium promoter load). This journal is
- Bauer, Eike B.,Talasila, Deva Saroja
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p. 36814 - 36820
(2021/12/02)
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- Palladium(ii)-assisted activation of thioglycosides
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Described herein is the first example of glycosidation of thioglycosides in the presence of palladium(ii) bromide. While the activation with PdBr2alone was proven feasible, higher yields and cleaner reactions were achieved when these glycosylat
- Escopy, Samira,Singh, Yashapal,Demchenko, Alexei V.
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p. 2044 - 2054
(2021/03/16)
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- Bismuth(iii) triflate as a novel and efficient activator for glycosyl halides
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Presented herein is the discovery that bismuth(iii) trifluoromethanesulfonate (Bi(OTf)3) is an effective catalyst for the activation of glycosyl bromides and glycosyl chlorides. The key objective for the development of this methodology is to em
- Steber, Hayley B.,Singh, Yashapal,Demchenko, Alexei V.
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p. 3220 - 3233
(2021/04/21)
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- Visible-light-promoted 3,5-dimethoxyphenyl glycoside activation and glycosylation
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A new glycosylation method promoted by visible light with 3,5-dimethoxyphenyl glycoside as the donor was developed. This protocol delivers bothO-glycosides andN-glycosides in moderate to excellent yields using a wide range ofO-nucleophiles and nucleobases as the glycosyl acceptors.
- Cao, Yafei,Li, Qin,Liu, Da-Ke,Liu, Jianhui,Mao, Run-Ze,Xia, Feng,Xiong, De-Cai,Ye, Xin-Shan,Zhou, Minmin,Zou, You
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p. 10899 - 10902
(2021/10/25)
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- A Mild Glycosylation Protocol with Glycosyl 1-Methylimidazole-2-carboxylates as Donors
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A mild glycosylation protocol is developed by using glycosyl 1-methylimidazole-2-carboxylates. Such a glycosylation can be promoted by a series of metal triflates and triflimides, especially Cu(OTf)2. The reaction is initiated by activation of
- Chen, Jianpeng,Tang, Yu,Yu, Biao
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p. 4333 - 4344
(2021/07/26)
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- Evaluating the reactivity and stereoselectivity of salicyl-type thioglycosides as non-malodorous thioglycoside alternatives for oligosaccharide synthesis
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Herein, o-(methoxycarbonyl)phenyl thioglycosides [or (methyl)salicyl 1-thioglycosides] were evaluated as non-malodorous thioglycoside alternatives. The o-methoxycarbonyl group was expected to assist in the departure of leaving group. Salicyl-type thioglyc
- Dohi, Hirofumi,Sakurai, Risa,Tamura, Manami,Komai, Ryota,Nishida, Yoshihiro
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- NIS/TMSOTf-Promoted Glycosidation of Glycosyl ortho-Hexynylbenzoates for Versatile Synthesis of O-Glycosides and Nucleosides
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Glycosidation plays a pivotal role in the synthesis of O-glycosides and nucleosides that mediate a diverse range of biological processes. However, efficient glycosidation approach for the synthesis of both O-glycosides and nucleosides remains challenging in terms of glycosidation yields, mild reaction conditions, readily available glycosyl donors, and cheap promoters. Here, we report a versatile N-iodosuccinimide/trimethylsilyl triflate (NIS/TMSOTf)-promoted glycosidation approach with glycosyl ortho-hexynylbenzoates as donors for the highly efficient synthesis of O-glycosides and nucleosides. The glycosidation approach highlights the merits of mild reaction conditions, cheap promoters, extremely wide substrate scope, and good to excellent yields. Notably, the glycosidation approach performs very well in the construction of a series of challenging O- and N-glycosidic linkages. The glycosidation approach is then applied to the efficient synthesis of oligosaccharides via the one-pot strategy and the stepwise strategy. On the basis of the isolation and characterization of the departure species derived from the leaving group, a plausible mechanism of NIS/TMSOTf-promoted glycosidation of glycosyl ortho-hexynylbenzoates is proposed.
- Liu, Rongkun,Hua, Qingting,Lou, Qixin,Wang, Jiazhe,Li, Xiaona,Ma, Zhi,Yang, You
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p. 4763 - 4778
(2021/04/06)
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- A Highly Efficient Glycosidation of Glycosyl Chlorides by Using Cooperative Silver(I) Oxide–Triflic Acid Catalysis
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Following our discovery that silver(I) oxide-promoted glycosylation with glycosyl bromides can be greatly accelerated in the presence of catalytic TMSOTf or TfOH, we report herein a new discovery that glycosyl chlorides are even more effective glycosyl do
- Geringer, Scott A.,Singh, Yashapal,Hoard, Daniel J.,Demchenko, Alexei V.
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p. 8053 - 8063
(2020/06/05)
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- Indolylthio glycosides as effective building blocks for chemical glycosylation
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The S-indolyl (SIn) anomeric moiety was investigated as a new leaving group that can be activated for chemical glycosylation under a variety of conditions including thiophilic and metal-assisted pathways. Understanding of the reaction pathways for the SIn moiety activation was achieved via the extended mechanistic study. Also reported is how the new SIn donors fit into selective activation strategies for oligosaccharide synthesis.
- Demchenko, Alexei V.,Shrestha, Ganesh,Panza, Matteo,Singh, Yashapal,Rath, Nigam P.
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p. 15885 - 15894
(2021/01/19)
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- Ortho-(1-phenylvinyl)benzoate glycosylation donor, and preparation method and application thereof
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The invention discloses an ortho-(1-phenylvinyl)benzoate glycosylation donor, and a preparation method and an application thereof in a glycosylation reaction. The ortho-(1-phenylvinyl)benzoate glycosylation donor is stable, is easy to prepare and store, and is widely applied to the construction of various oxygen glucosides and nucleoside (nitrogen glucoside) glycosidic bonds. The leaving group ofthe donor is an alkenyl ester, has a high activity, and can be combined with thioglycoside or n-pentenyl ether glucoside through a one-pot glycosylation reaction to synthesize oligosaccharide. The glycosylation reaction conditions are mild, and receptors sensitive to acid and electrophilic reagents can tolerate the glycosylation reaction conditions.
- -
-
Paragraph 0103; 0107-0109; 0112-0113
(2020/05/01)
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- Synthesis of Glycosyl Chlorides and Bromides by Chelation Assisted Activation of Picolinic Esters under Mild Neutral Conditions
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A general method has been developed for the formation of glycosyl chlorides and bromides from picolinic esters under mild and neutral conditions. Benchtop stable picolinic esters are activated by a copper(II) halide species to afford the corresponding products in high yields with a traceless leaving group. Rare β glycosyl chlorides are accessible via this route through neighboring group participation. Additionally, glycosyl chlorides with labile protecting groups previously not easily accessible can be prepared.
- Balzer, Paul G.,Blaszczyk, Stephanie A.,Duan, Xiyan,Ma, Zhi-Xiong,Simmons, Christopher J.,Stevens, Christopher M.,Tang, Weiping,Wang, Hao-Yuan,Wen, Peng,Ye, Wenjing,Yin, Dan
-
supporting information
(2020/02/28)
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- Gold(I)-Catalyzed Glycosylation with Glycosyl Ynenoates as Donors
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A simple and versatile glycosylation method with both armed and disarmed glycosyl ynenoates as donors is developed. Employing a gold(I) complex as catalyst with or without the assistance of TfOH, the scope of the present glycosylation protocol is very wid
- Li, Xiaona,Li, Chenyu,Liu, Rongkun,Wang, Jiazhe,Wang, Zixuan,Chen, Yan,Yang, You
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p. 9693 - 9698
(2019/11/29)
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- Koenigs–Knorr Glycosylation Reaction Catalyzed by Trimethylsilyl Trifluoromethanesulfonate
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The discovery that traditional silver(I)-oxide-promoted glycosidations of glycosyl bromides (Koenigs–Knorr reaction) can be greatly accelerated in the presence of catalytic trimethylsilyl trifluoromethanesulfonate (TMSOTf) is reported. The reaction conditions are very mild that allowed for maintaining a practically neutral pH and, at the same time, providing high rates and excellent glycosylation yields. In addition, unusual reactivity trends among a series of differentially protected glycosyl bromides were documented. In particular, benzoylated α-bromides were much more reactive than their benzylated counterparts under these conditions.
- Singh, Yashapal,Demchenko, Alexei V.
-
supporting information
p. 1461 - 1465
(2019/01/04)
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- Glycosylation with 3,5-Dimethyl-4-(2′-phenylethynylphenyl)phenyl (EPP) Glycosides via a Dearomative Activation Mechanism
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A highly effective and versatile glycosylation method is developed, which uses 3,5-dimethyl-4-(2′-phenylethynylphenyl)phenyl (EPP) glycosides as donors and NIS/TMSOTf as promoter and proceeds via an unprecedented dearomative activation mechanism.
- Hu, Zhifei,Tang, Yu,Yu, Biao
-
supporting information
p. 4806 - 4810
(2019/03/26)
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- O-Glycosylation Enabled by N-(Glycosyloxy)acetamides
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A novel glycosylation protocol has been established by using N-(glycosyloxy)acetamides as glycosyl donors. The N-oxyacetamide leaving group in donors could be rapidly activated in the presence of Cu(OTf)2 or SnCl4 under microwave irr
- Liu, Miao,Li, Bo-Han,Xiong, De-Cai,Ye, Xin-Shan
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p. 8292 - 8303
(2018/07/05)
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- Investigation of Glycosyl Nitrates as Building Blocks for Chemical Glycosylation
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Glycosyl nitrates are important synthetic intermediates in the synthesis of 2-amino sugars, 1,2-orthoesters or, more recently, 2-OH glucose. However, glycosyl nitrates have never been glycosidated. Presented herein is our first attempt to use glycosyl nitrates as glycosyl donors for O-glycosylation. Lanthanide triflates showed good affinity to activate the nitrate leaving group.
- Wang, Tinghua,Singh, Yashapal,Stine, Keith J.,Demchenko, Alexei V.
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p. 6699 - 6705
(2018/11/23)
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- Regenerative Glycosylation
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Previously, we communicated 3,3-difluoroxindole (HOFox)-mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates. Both the in situ synthesis from the corresponding glycosyl bromides and activation of the OFox imidates could be conducted in a regenerative fashion. Herein, we extend this study to the synthesis of various glycosidic linkages using different sugar series. The main outcome of this study relates to enhanced yields and/or reduced reaction times of glycosylations. The effect of HOFox-mediated reactions is particularly pronounced in case of unreactive glycosyl donors and/or glycosyl acceptors. A multistep regenerative synthesis of oligosaccharides is also reported.
- Singh, Yashapal,Wang, Tinghua,Geringer, Scott A.,Stine, Keith J.,Demchenko, Alexei V.
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p. 374 - 381
(2018/01/01)
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- Mechanism investigations of the activation process of S-2-[(propan-2-yl)sulfinyl]benzyl (SPSB) glycosides
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In our recently developed interrupted Pummerer reaction mediated (IPRm) glycosylation with S-2-[(propan-2-yl)sulfinyl] benzyl (SPSB) glycosides as glycosyl donors, the anomeric leaving groups were recovered in the forms of thiosulfinate, disulfide and thi
- Chen, Wei,Zeng, Jing,Liao, Zhiwen,Teng, Shuang,Xiao, Xiong,Meng, Lingkui,Wan, Qian
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p. 498 - 506
(2019/04/10)
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- Iron(iii) chloride-catalyzed activation of glycosyl chlorides
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Glycosyl chlorides have historically been activated using harsh conditions and/or toxic stoichiometric promoters. More recently, the Ye and the Jacobsen groups showed that glycosyl chlorides can be activated under organocatalytic conditions. However, thos
- Geringer, Scott A.,Demchenko, Alexei V.
-
supporting information
p. 9133 - 9137
(2019/01/03)
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- Acid-Catalyzed O-Glycosylation with Stable Thioglycoside Donors
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Two classes of thioglycoside, 4-(4-methoxyphenyl)-3-butenylthioglycosides (MBTGs) and 4-(4-methoxyphenyl)-4-pentenylthioglycosides (MPTGs), undergo acid-catalyzed O-glycosylations with a range of sugar and nonsugar alcohols at 25 °C. Electron density at t
- Lacey, Kristina D.,Quarels, Rashanique D.,Du, Shaofu,Fulton, Ashley,Reid, Nicholas J.,Firesheets, Austin,Ragains, Justin R.
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supporting information
p. 5181 - 5185
(2018/09/12)
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- Radical halogenation-mediated latent-active glycosylations of allyl glycosides
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Radical halogenation-mediated glycosylation using allyl glycosides as donors and as acceptors emerges to be an efficient and hither-to unknown glycosylation method, adhering to the concept of the latent-active methodology. Several di- and trisaccharides that possess the allyl moiety at their reducing end are prepared through this new glycosylation methodology.
- Pal, Rita,Das, Anupama,Jayaraman, Narayanaswamy
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p. 588 - 590
(2018/01/28)
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- Dehydrative glycosylation with cyclic phosphonium anhydrides
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Cyclic phosphonium anhydrides generated from bis-phosphine oxides and trifluoromethanesulfonic anhydride are shown as general coupling reagents in a dehydrative glycosylation reaction of C1-hemiacetals. This reaction protocol is characterized by a broad substrate scope and high yields, including reactions of O-, C-, N-, and S-based nucleophiles with furanose, pyranose, and deoxysugar donors.
- Dyapa, Rajendar,Dockery, Lance T.,Walczak, Maciej A.
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supporting information
p. 51 - 55
(2016/12/27)
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- Co2(CO)6-propargyl cation mediates glycosylation reaction by using thioglycoside
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We discovered that the cobalt-propargyl cation can mediate the glycosylation reaction by activating the thioglycoside donor. The glyco-oxacarbenium cation was formed by transferring the thio-aglycone to the cobalt-propargyl cation that was generated from the cobalt-propargylated acceptor in situ via the activating with Lewis acid. The reactivity of the donor (Armed or dis-armed) and the amount of the Lewis acid control the releasing rate of the cobalt-propargyl group.
- Xia, Meng-jie,Yao, Wang,Meng, Xiang-bao,Lou, Qing-hua,Li, Zhong-jun
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supporting information
p. 2389 - 2392
(2017/05/29)
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- OFox imidates as versatile glycosyl donors for chemical glycosylation
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Previously we communicated 3,3-difluoroxindole (HOFox)-mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates. Both the in situ synthesis from the corresponding glycosyl bromides and activation of the
- Nigudkar, Swati S.,Wang, Tinghua,Pistorio, Salvatore G.,Yasomanee, Jagodige P.,Stine, Keith J.,Demchenko, Alexei V.
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p. 348 - 359
(2017/01/13)
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- O-(p-Methoxyphenylethynyl)phenyl Glycosides: Versatile New Glycosylation Donors for the Highly Efficient Construction of Glycosidic Linkages
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A novel alkyne-activation-based glycosylation protocol using o-(p-methoxyphenylethynyl)phenyl (MPEP) glycoside was established. The glycosyl MPEP donors were shelf-stable and could be prepared efficiently via Sonogashira reaction from the corresponding o-
- Hu, Yang,Yu, Ke,Shi, Li-Li,Liu, Lei,Sui, Jing-Jing,Liu, De-Yong,Xiong, Bin,Sun, Jian-Song
-
supporting information
p. 12736 - 12744
(2017/09/25)
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- S-Benzimidazolyl (SBiz) Imidates as a Platform for Oligosaccharide Synthesis via Active-Latent, Armed-Disarmed, Selective, and Orthogonal Activations
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This article describes the development of S-benzimidazolyl (SBiz) imidates as versatile building blocks for oligosaccharide synthesis. The SBiz imidates have been originally developed as a new platform for active-latent glycosylations. This article expands upon the utility of these compounds. The application to practically all common concepts for the expeditious oligosaccharide synthesis including selective, chemoselective, and orthogonal strategies is demonstrated. The strategy development was made possible thanks to our enhanced understanding of the reaction mechanism and the modes by which SBiz imidates interact with various promoters of glycosylation.
- Hasty, Scott J.,Bandara, Mithila D.,Rath, Nigam P.,Demchenko, Alexei V.
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supporting information
p. 1904 - 1911
(2017/03/01)
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- Isoquinoline-1-Carboxylate as a Traceless Leaving Group for Chelation-Assisted Glycosylation under Mild and Neutral Reaction Conditions
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Glycosyl isoquinoline-1-carboxylate was developed as a novel benchtop stable and readily available glycosyl donor. The glycosylation reaction was promoted by the inexpensive Cu(OTf)2 salt under mild reaction conditions. The copper isoquinoline-1-carboxylate salt was precipitated from the solution and thus rendered a traceless leaving group. Surprisingly, the proton from the acceptor was absorbed by the precipitated metal complex and the reaction mixture remained at neutral pH. The copper-promoted glycosylation was also proven to be completely orthogonal to the gold-promoted glycosylation, and an iterative synthesis of oligosaccharides from benchtop stable anomeric ester building blocks becomes possible under mild reaction conditions.
- Wang, Hao-Yuan,Simmons, Christopher J.,Blaszczyk, Stephanie A.,Balzer, Paul G.,Luo, Renshi,Duan, Xiyan,Tang, Weiping
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supporting information
p. 15698 - 15702
(2017/11/13)
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- Glycosyl ortho-Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group
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We describe the β-ortho-methoxybenzoate as a shelf stable and practical C-1 nucleofuge for catalytic chemical glycosylation in which the benzoic acid by-product can be easily removed, reisolated, and potentially recycled after the glycosylation reaction. This new type of glycosyl donor can be efficiently activated by a range of promoters, including Bi(OTf)3, Fe(OTf)3, TMSOTf (TMS = trimethylsilyl), and triflic acid, with low (10 mol-%) catalyst loadings. The donor shows higher reactivity than analogous benzoate, p-methoxybenzoate and p-cyano-o-methoxybenzoate donors. In glycosylation reactions with o-methoxybenzoate donors, the yields of disaccharide products were good to excellent for various glycosyl acceptors, including a carbohydrate-based secondary alcohol. Furthermore, β-selective mannosylation was achieved with a Crich-type donor at 0 °C to ambient temperature, without donor preactivation. The donor was also used for the first step of a one-pot two-step glycosylation to obtain a trisaccharide; the second coupling involved activation of a thioglycoside with NIS/TMSOTf (NIS = N-iodosuccinimide). We believe that this offers a good alternative to current protocols.
- Kristensen, Steffan K.,Salamone, Stéphane,Rasmussen, Michelle R.,Marqvorsen, Mikkel H. S.,Jensen, Henrik H.
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p. 5365 - 5376
(2016/11/22)
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- Remote Activation of Disarmed Thioglycosides in Latent-Active Glycosylation via Interrupted Pummerer Reaction
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S-glycosides, S-2-(2-propylthio)benzyl (SPTB) glycosides, were converted to the corresponding oxidized glycosyl donors, S-2-(2-propylsulfinyl)benzyl (SPSB) glycosides, by simple and selective oxidation. Treatment of disarmed SPSB donor and various acceptors with triflic anhydride provided the desired glycosides in good to excellent yields. Meanwhile, observation of thiosulfinate, thiosulfonate, and disulfide suggested that the leaving group was activated via an interrupted Pummerer reaction. The disarmed SPSB thioglycosyl donors could be selectively activated in the presence of various thioglycosides with remote activation mode. Finally, two natural hepatoprotective glycosides, Leonoside E and Leonuriside B, were efficiently synthesized in a convergent manner with this newly developed method.
- Xiao, Xiong,Zhao, Yueqi,Shu, Penghua,Zhao, Xiang,Liu, Yan,Sun, Jiuchang,Zhang, Qian,Zeng, Jing,Wan, Qian
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supporting information
p. 13402 - 13407
(2016/10/22)
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- Glycosyl alkoxythioimidates as building blocks for glycosylation: A reactivity study
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Structural modifications of the leaving group of S-glycosyl O-methyl phenylcarbamothioates (SNea) involving change of substituents that express different electronic effects led to a better understanding of how the reactivity of these glycosyl donors can b
- Ranade, Sneha C.,Demchenko, Alexei V.
-
p. 115 - 122
(2015/02/19)
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- 2-Pyridyl glycoside: An alternative glycosyl donor in preactivation protocol
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2-Pyridyl glycosides have been identified to be powerful glycosyl donors for the preactivation-based oligosaccharide synthesis. By using stoichiometric amount of Tf2O, the 2-pyridyl glycosides were pre-activated, which subsequently underwent gl
- Xiong, De-Cai,Yang, An-Qi,Yu, Yang,Ye, Xin-Shan
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p. 211 - 214
(2015/02/05)
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- Regenerative glycosylation under nucleophilic catalysis
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This article describes 3,3-difluoroxindole (HOFox)-mediated glycosylation. The uniqueness of this approach is that both the in situ synthesis of 3,3-difluoro-3H-indol-2-yl (OFox) glycosyl donors and activation thereof can be conducted in a regenerative fashion as is a typical reaction performed under nucleophilic catalysis. Only a catalytic amount of the OFox imidate donor and a Lewis acid activator are present in the reaction medium. The OFox imidate donor is constantly regenerated upon its consumption until glycosyl acceptor has reacted.
- Nigudkar, Swati S.,Stine, Keith J.,Demchenko, Alexei V.
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supporting information
p. 921 - 923
(2014/02/14)
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- Thioperoxide-mediated activation of thioglycoside donors
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Thioperoxide (1) in combination with trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides a powerful thiophilic promoter system, capable of activating different thioglycosides. Both armed and disarmed thioglycosides were activated effectively in the
- He, Hongwen,Zhu, Xiangming
-
supporting information
p. 3102 - 3105
(2014/06/23)
-
- Glycosidation reactions of benzyl-type selenoglycoside donors
-
p-Methoxybenzyl (PMB), and p-nitrobenzyl (PNB) selenoglycosides of glucose were synthesized, and their glycosidation reactions were investigated. The Bn and PNB derivatives were successfully activated with IBr-AgClO4 to provide the glycosylated products in high yields. The glycosidation with the PMB derivatives required promotion with a metal triflate, such as (CuOTf)2·PhMe or In(OTf)3, and afforded the glycosylated products in medium to high yields.
- Menjo, Masanori,Tamai, Hideki,Ando, Hiromune,Ishida, Hideharu,Koketsu, Mamoru,Kiso, Makoto
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p. 1587 - 1594
(2016/11/07)
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- A comparative study of glycosyl thioimidates as building blocks for chemical glycosylation
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Our results indicate that the reactivity and the activation profile of thioimidate glycosyl donors vary significantly depending on the endocyclic heteroatom (N,O,S). Reactivity diminishes in accordance with the following sequence: O > S > N; and this tren
- Ranade, Sneha C.,Hasty, Scott J.,Demchenko, Alexei V.
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p. 360 - 379
(2013/10/08)
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- Glycosylation of alcohols using glycosyl boranophosphates as glycosyl donors
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A novel glycosylation that uses glycosyl boranophosphate triesters as glycosyl donors and trityl cation (Tr+) as an activator was developed. Two types of reactions were studied: (1) the boranophosphate triester was activated with TrNTf2 to react with an alcohol and (2) O-trityl ethers worked as both glycosyl acceptors and Tr+ sources. The latter gave better results and the desired O-glycosylation products were rapidly generated and isolated in moderate to good yields.
- Tatsumi, Shiro,Matsumura, Fumiko,Oka, Natsuhisa,Wada, Takeshi
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supporting information
p. 3731 - 3734
(2013/07/05)
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- O-Benzoxazolyl imidates as versatile glycosyl donors for chemical glycosylation
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Herein, we report a new class of glycosyl donors, benzoxazolyl imidates, for chemical glycosylation. The O-benzoxazolyl (OBox) leaving group was designed with an aim to compare the relative reactivity and stability of similarly structured S-benzoxazolyl (
- Nigudkar, Swati S.,Parameswar, Archana R.,Pornsuriyasak, Papapida,Stine, Keith J.,Demchenko, Alexei V.
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supporting information
p. 4068 - 4076
(2013/07/05)
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- Glycosidation of thioglycosides in the presence of bromine: Mechanism, reactivity, and stereoselectivity
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Elaborating on previous studies by Lemieux for highly reactive "armed" bromides, we discovered that β-bromide of the superdisarmed (2-O-benzyl-3,4,6-tri-O-benzoyl) series can be directly obtained from the thioglycoside precursor. When this bromide is glycosidated, α-glycosides form exclusively; however, the yields of such transformations may be low due to the competing anomerization into α-bromide that is totally unreactive under the established reaction conditions.
- Kaeothip, Sophon,Yasomanee, Jagodige P.,Demchenko, Alexei V.
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experimental part
p. 291 - 299
(2012/03/08)
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- 2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis
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The O-allylphenyl (AP) anomeric moiety was investigated as a new leaving group that can be activated for chemical glycosylation under a variety of conditions, through both direct and remote pathways. Differentiation between the two activation pathways was achieved in a mechanistic study. The orthogonal-type activation of the AP moiety along with common thioglycosides allows for the execution of efficient oligosaccharide assembly.
- Premathilake, Hemali D.,Demchenko, Alexei V.
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p. 597 - 605
(2012/06/30)
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- Direct synthesis of diastereomerically pure glycosyl sulfonium salts
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It is reported that stable glycosyl sulfonium salts can be generated via direct anomeric S-methylation of ethylthioglycosides. Mechanistically, this pathway represents the first step in the activation of thioglycosides for glycosidation; however, it can f
- Mydock, Laurel K.,Kamat, Medha N.,Demchenko, Alexei V.
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supporting information; experimental part
p. 2928 - 2931
(2011/07/30)
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- Reverse orthogonal strategy for oligosaccharide synthesis
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Herein, we report the invention of a novel expeditious concept for oligosaccharide synthesis. Unlike the classic orthogonal strategy based on leaving groups, the reverse approach is based on orthogonal protecting groups, herein p-methoxybenzyl and 4-pentenoyl, which allows for efficient oligosaccharide assembly in the reverse direction.
- Fujikawa, Kohki,Ganesh, N. Vijaya,Tan, Yih Horng,Stine, Keith J.,Demchenko, Alexei V.
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scheme or table
p. 10602 - 10604
(2011/11/06)
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- S-benzimidazolyl glycosides as a platform for oligosaccharide synthesis by an active-latent strategy
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Doing the Biz: The S-benzimidazolyl (SBiz) anomeric moiety is a new leaving group that can be activated for glycosylation under a variety of conditions, including metal-assisted and alkylation pathways. Application of a substituted SBiz moiety (X=anisoyl, see picture) allows active-latent and armed-disarmed types of oligosaccharide assembly. Copyright
- Hasty, Scott J.,Kleine, Matthew A.,Demchenko, Alexei V.
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p. 4197 - 4201
(2011/07/07)
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- Glycosyl alkoxythioimidates as complementary building blocks for chemical glycosylation
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It is reported that S-glycosyl O-methyl phenylcarbamothioates (SNea carbamothioates) have a fully orthogonal character in comparison to S-benzoxazolyl (SBox) glycosides. This complete orthogonality was revealed by performing competitive glycosylation expe
- Ranade, Sneha C.,Kaeothip, Sophon,Demchenko, Alexei V.
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supporting information; experimental part
p. 5628 - 5631
(2011/03/20)
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- Unexpected orthogonality of S-benzoxazolyl and S-thiazolinyl glycosides: Application to expeditious oligosaccharide assembly
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Thorough mechanistic studies of the alkylation pathway for the activation of glycosyl thioimidates have led to the development of the " thioimidateonly orthogonal strategy". Discrimination among S-thiazolinyl (STaz) and S-benzoxazolyl (SBox) anomeric leav
- Kaeothip, Sophon,Pornsuriyasak, Papapida,Rath, Nigam P.,Demchenko, Alexei V.
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supporting information; experimental part
p. 799 - 802
(2009/09/05)
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- Silver(I) tetrafluoroborate as a potent promoter for chemical glycosylation
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We have identified silver tetrafluoroborate (AgBF4) as an excellent promoter for the activation of various glycosyl donors including glycosyl halides, trichloroacetimidates, and thioimidates. Easy handling and no requirement for azeotropic dehydration prior to application makes AgBF4 especially beneficial in comparison to the commonly used AgOTf. Selective activation of glycosyl halides or thioimidates over thioglycosides or n-pentenyl glycosides, including simple sequential one-pot syntheses, has also been demonstrated. Versatility of glycosyl thioimidates was further explored by converting these intermediates into a variety of other classes of glycosyl donors.
- Kaeothip, Sophon,Pornsuriyasak, Papapida,Demchenko, Alexei V.
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p. 1542 - 1545
(2008/09/19)
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