40246-33-1Relevant academic research and scientific papers
Photolabile 2-(2-Nitrophenyl)-propyloxycarbonyl (NPPOC) for Stereoselective Glycosylation and Its Application in Consecutive Assembly of Oligosaccharides
Wang, Jincai,Feng, Yingle,Sun, Taotao,Zhang, Qi,Chai, Yonghai
, p. 3402 - 3421 (2022/03/02)
A photolabile protecting group (PPG) 2-(2-nitrophenyl)-propyloxycarbonyl (NPPOC) was explored in glycosylation and applied in the consecutive synthesis of oligosaccharides. NPPOC displays a strong neighboring group participation (NGP) effect to facilitate the construction of 1,2-trans glycosides in excellent yield. Notably, NPPOC could be efficiently removed by photolysis, and the deprotection conditions are friendly to typical protecting groups. A branched and asymmetric oligomannose Man6 was rapidly prepared, and the consecutive assembly of oligosaccharides without intermediate purification was further investigated owing to the compatibility conditions between NPPPOC's photolysis and glycosylation.
C2-(1 N/2 N-Methyl-tetrazole)methyl Ether (MeTetMe) as a Stereodirecting Group for 1,2-trans-β-O-Glycosylation
Rahaman Molla, Mosidur,Thakur, Rima
, p. 5732 - 5745 (2021/11/11)
Development of stereoselective synthetic methods for O-glycosides is of paramount importance in the field of glycochemistry. Therefore, we report herein (1 N/2 N)-methylated tetrazole methyl (MeTetMe) ethers as a C2-directing group for the formation of 1,2-trans-β-O-glycosides. The synthesis of the tetrazole moiety was readily achieved by a 3+2 cycloaddition reaction on nitrile functionality. The tethered thioglycoside donors were found to deliver the β-O-glycosides when activated by PIFA-TfOH reagent system. The reactions were performed with six newly synthesized phenyl and ethyl thioglycosides to obtain the glycosylated adducts in moderate to high yields and excellent to exclusive β-selectivity. The glycosylation method was easily scalable up to grams without affecting the yield and stereoselectivity. The MeTetMe group was efficiently removed under Birch reduction conditions without affecting the benzyl ethers or isopropylidene acetal protection.
Cyanomethyl Ether as an Orthogonal Participating Group for Stereoselective Synthesis of 1,2-trans-β-O-Glycosides
Molla, Mosidur Rahaman,Das, Pradip,Guleria, Kanika,Subramanian, Ranga,Kumar, Amit,Thakur, Rima
, p. 9955 - 9968 (2020/09/09)
Stereoselective formation of glycosidic linkages has been the prime focus for contemporary carbohydrate chemistry. Herein, we report cyanomethyl (CNMe) ether as an efficient and effective participating orthogonal protecting group for the stereoselective synthesis of 1,2-trans-β-O-glycosides. The participating group facilitated good to high β-selective glycosylation with a broad range of electron-rich and electron-deficient glycosyl acceptors. Detailed experimental and theoretical studies reveal the involvement of CNMe ether in the formation of a six-membered imine-type cyclic intermediate for the observed stereoselectivity. Rapid incorporation and selective removal of the CNMe ether group in the presence of benzyl ether and isopropylidene acetal protection have also been reported here. The nitrile group provided an opportunity for the glycodiversification through further derivatizations.
Protecting Group Dependence of Stereochemical Outcome of Glycosylation of 2-O-(Thiophen-2-yl)methyl Ether Protected Glycosyl Donors
Watson, Andrew J. A.,Alexander, Stewart R.,Cox, Daniel J.,Fairbanks, Antony J.
, p. 1520 - 1532 (2016/04/05)
A series of glycosyl donors possessing a (thiophen-2-yl)methyl ether protecting group at position 2 were synthesised and the effect of the protecting group pattern of other hydroxyls on the stereochemical outcome of glycosylation was investigated. Studies revealed optimal α-selectivity for glycosylation using a fully armed tri-benzylated donor, whilst other protecting group patterns were significantly less effective. Low-temperature NMR studies of both fully armed and fully disarmed donors revealed the intermediacy of cyclised sulfonium ion intermediates. Reaction conditions were developed which allowed removal of the (thiophen-2-yl)methyl ether protecting group either selectively, or together with benzyl ethers. Glycosyl donors with a 2-O-thiophenylmethyl ether protecting group undergo six-membered ring NGP, as demonstrated by low-T NMR studies, but the stereochemical outcome of glycosylation is highly dependent on other protecting groups.
Neighbouring group participation during glycosylation: Do 2-substituted ethyl ethers participate?
Cox, Daniel J.,Singh, Govind P.,Watson, Andrew J. A.,Fairbanks, Antony J.
, p. 4624 - 4642 (2014/08/05)
The development of new protecting groups that undergo neighbouring group participation (NGP) via six-membered ring intermediates to promote the formation of α-1,2-cis glycosidic linkages complements the established use of 5-ring NGP in terms of stereochem
Stereoselective glycosylations using oxathiane spiroketal glycosyl donors
Fascione, Martin A.,Webb, Nicola J.,Kilner, Colin A.,Warriner, Stuart L.,Turnbull, W. Bruce
experimental part, p. 6 - 13 (2012/03/27)
Novel oxathiane spiroketal donors have been synthesised and activated via an umpolung S-arylation strategy using 1,3,5-trimethoxybenzene and 1,3-dimethoxybenzene. The comparative reactivity of the resulting 2,4,6-trimethoxyphenyl (TMP)- and 2,4-dimethoxyp
Do glycosyl sulfonium ions engage in neighbouring-group participation? A Study of oxathiane glycosyl donors and the basis for their stereoselectivity
Fascione, Martin A.,Kilner, Colin A.,Leach, Andrew G.,Turnbull, W. Bruce
supporting information; experimental part, p. 321 - 333 (2012/03/09)
Neighbouring-group participation has long been used to control the synthesis of 1,2-trans-glycosides. More recently there has been a growing interest in the development of similar strategies for the synthesis of 1,2-cis-glycosides, in particular the use of auxiliary groups that generate sulfonium ion intermediates. However, there has been some debate over the role of sulfonium ion intermediates in these reactions: do sulfonium ions actually engage in neighbouring-group participation, or are they a resting state of the system prior to reaction through an oxacarbenium ion intermediate? Herein, we describe the reactivities and stereoselectivities of a family of bicyclic thioglycosides in which an oxathiane ring is fused to the sugar to form a trans-decalin-like structure. A methyl sulfonium ion derived from one such glycosyl donor is so stable that it can be crystallised from ethanol, yet it reacts with complete stereoselectivity at high temperature. The importance of a ketal group in the oxathiane ring for maintaining this high stereoselectivity is investigated using a combination of experiment and ab initio calculations. The data are discussed in terms of SN1 and SN2 type mechanisms. Trends in stereoselectivity across a series of compounds are more consistent with selective addition to oxacarbenium ions rather than a shift between SN1 and SN2 mechanisms. Copyright
Stereoselective glycosylation using oxathiane glycosyl donors
Fascione, Martin A.,Adshead, Sophie J.,Stalford, Susanne A.,Kilner, Colin A.,Leach, Andrew G.,Turnbull, W. Bruce
supporting information; experimental part, p. 5841 - 5843 (2010/01/31)
A bicyclic glycosyl donor is activated as an arylsulfonium ion and used to synthesise α-glycosides with high stereoselectivity.
Stereospecific synthesis of 1,2-cis glycosides by vinyl-mediated IAD
Chayajarus, Kampanart,Chambers, David J.,Chughtai, Majid J.,Fairbanks, Antony J.
, p. 3797 - 3800 (2007/10/03)
(Chemical Equation Presented) Stereospecific 1,2-cis glycosylation of 2-O-vinyl thioglycosides, synthesized from the corresponding alcohols by Ir-catalyzed transvinylation with vinyl acetate, is achieved by iodine-mediated tethering of a range of primary
