Dithiols. Part XXIV. Proof of the epoxide chirality in 2,3-epoxypropyl β-<scp>D</scp>-glucopyranoside by correlation with (R)-2,3-thiocarbonyldithiopropanol

Jesudason, Malini V.; Owen, L. N.

doi:10.1039/p19740001443

“…Theoretically, the alkoxide could attack this regioisomer to afford the 2- O -alkyl-idopyranoside; however, this byproduct was never observed in the crude 1 H NMR. This was likely a result of 2,3-anhydro- d -gulo- and talopyranosides preferring to adopt an O H 5 half-chair conformation; the O H 5 conformation can be confirmed via 1 H NMR coupling constants between vicinal H-1 and H-4 protons: a very small coupling constant (<1.5 Hz) when the relationship is trans, and a slightly larger coupling constant (<5.6 Hz) when the relationship is cis. , It was previously demonstrated that in this preferred O H 5 conformation, the approach of a nucleophile to attack the epoxide ring is significantly more sterically hindered in the gulo - as compared to the talo -stereoisomer; − this interference of approach of the nucleophile could prevent the gulo -epoxide from reacting at room temperature. This decreased reactivity was confirmed by reacting the gulo -epoxide ( 11 ) with sodium methoxide: after several days at room temperature and even heating at 70 °C for 18 h, it was found that the reaction did not go to completion.…”

Section: Resultsmentioning

confidence: 99%

A Scalable Approach to Obtaining Orthogonally Protected β-d-Idopyranosides

Hevey

¹

,

Morland

²

,

Ling

³

2012

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A practical method to obtain orthogonally protected D-idopyranose from D-galactose has been developed, which is the first method to enable synthesis of the challenging β-D-idopyranoside linkage. The method relies on a key double inversion at O-2 and O-3 in an easily prepared D-galactose derivative, which proceeds regio- and stereoselectively through a 2,3-anhydrotalopyranoside; reaction using a selection of alkoxides affords exclusively the 3-O-alkylidopyranoside, which can be used to generate an orthogonally protected monosaccharide. The process is scalable and requires minimal purification, so it could be used to produce building blocks to aid in the synthesis of various β-idopyranose-containing oligosaccharide targets to further probe their biological functions.

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“…The large coupling constant J 1,2 = 5.0 Hz implies that the epithio groups are of allo-type rather than manno-type, after previous reports that J 1,2 = 4.4 and 0 Hz for methyl 2,3dideoxy-2,3-epithio-4,6-di-O-methyl-a-d-alloside or -mannoside, respectively. [9] Moreover, when the chemical shifts of C-2 and C-3 are compared with the corresponding values for mono-alloepoxy-b-cyclodextrin, the upfield shifts of Dd C2 = 17.4 ppm and Dd C3 = 16.1 ppm are similar in magnitude. However, such similarity in the upfield shifts is not observed in comparison with mono-mannoepoxy-b-cyclodextrin, Dd C2 = 10.3 ppm and Dd C3 = 17.9 ppm, which again supports the proposed allo structure of 2.…”

mentioning

confidence: 90%

Synthesis of a Cycloallin Derivative from β‐Cyclodextrin: Heptakis(2,3‐dideoxy‐2,3‐epithio)‐β‐cycloallin

Fukudome

¹

,

Shiratani

²

,

Immel

³

et al. 2005

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Macrocyclic molecules that comprise several subunits in a circular array exhibit novel functions that are otherwise not observed in the individual units. Many host molecules that consist of several identical functional subunits, such as cyclodextrins, cyclophanes, and their related natural and artificial macrocycles, have been prepared by enzymatic or synthetic methods and have developed the concept of artificial molecular recognition and catalysis.[1] Cyclodextrins, in particular, have been the leading compounds from the initial stage of this research. Despite extensive studies on the functionalization of cyclodextrins for diverse purposes such as the development of artificial receptors and enzymes, their modification has been limited mostly to their primary hydroxy groups while secondary sites have received much less attention.[2] Moreover, successful studies on complete modifications at the secondary sites are rare as the modifications on 2-OH or 3-OH do not proceed selectively and are accompanied inevitably by products of either over-or undermodification. Only per(3,6-anhydro)- [3] and per(2-O-tosyl)-cyclodextrins, [4] per(2,3-anhydro)-cyclomannins 1 (see Scheme 1), [4,5] cycloaltrins, [6] per(3-amino-3-deoxy)-b-cycloaltrin, [7] and per(3-deoxy)-cyclomannins [8] are available by the selective modifications of cyclodextrins at the present time. However, to the best of our knowledge, the preparation of a cycloallin family has not been studied as yet.Here, we report the first successful one-pot preparation of a novel type of cycloallin derivative, 2, from cyclomannin derivative 1, which itself is obtained in three steps from bcyclodextrin (Scheme 1). The synthesis is as simple as heating an aqueous acidic solution of 1 at 90 8C for 30 min followed by stirring at room temperature under alkaline conditions. It is quite astonishing that these simple reaction conditions not only ensure a complete conversion of the seven epoxide

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“…[9] Moreover, when the chemical shifts of C-2 and C-3 are compared with the corresponding values for mono-alloepoxy-b-cyclodextrin, the upfield shifts of Dd C2 = 17.4 ppm and Dd C3 = 16.1 ppm are similar in magnitude. [9] Moreover, when the chemical shifts of C-2 and C-3 are compared with the corresponding values for mono-alloepoxy-b-cyclodextrin, the upfield shifts of Dd C2 = 17.4 ppm and Dd C3 = 16.1 ppm are similar in magnitude.…”

mentioning

confidence: 90%

Synthesis of a Cycloallin Derivative from β‐Cyclodextrin: Heptakis(2,3‐dideoxy‐2,3‐epithio)‐β‐cycloallin

Fukudome¹,

Shiratani²,

Immel³

et al. 2005

Angewandte Chemie

0

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Macrocyclic molecules that comprise several subunits in a circular array exhibit novel functions that are otherwise not observed in the individual units. Many host molecules that consist of several identical functional subunits, such as cyclodextrins, cyclophanes, and their related natural and artificial macrocycles, have been prepared by enzymatic or synthetic methods and have developed the concept of artificial molecular recognition and catalysis.[1] Cyclodextrins, in particular, have been the leading compounds from the initial stage of this research. Despite extensive studies on the functionalization of cyclodextrins for diverse purposes such as the development of artificial receptors and enzymes, their modification has been limited mostly to their primary hydroxy groups while secondary sites have received much less attention.[2] Moreover, successful studies on complete modifications at the secondary sites are rare as the modifications on 2-OH or 3-OH do not proceed selectively and are accompanied inevitably by products of either over-or undermodification. Only per(3,6-anhydro)- [3] and per(2-O-tosyl)-cyclodextrins, [4] per(2,3-anhydro)-cyclomannins 1 (see Scheme 1), [4,5] cycloaltrins, [6] per(3-amino-3-deoxy)-b-cycloaltrin, [7] and per(3-deoxy)-cyclomannins [8] are available by the selective modifications of cyclodextrins at the present time. However, to the best of our knowledge, the preparation of a cycloallin family has not been studied as yet.Here, we report the first successful one-pot preparation of a novel type of cycloallin derivative, 2, from cyclomannin derivative 1, which itself is obtained in three steps from bcyclodextrin (Scheme 1). The synthesis is as simple as heating an aqueous acidic solution of 1 at 90 8C for 30 min followed by stirring at room temperature under alkaline conditions. It is quite astonishing that these simple reaction conditions not only ensure a complete conversion of the seven epoxide

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Dithiols. Part XXIV. Proof of the epoxide chirality in 2,3-epoxypropyl β-D-glucopyranoside by correlation with (R)-2,3-thiocarbonyldithiopropanol

Cited by 18 publications

References 1 publication

A Scalable Approach to Obtaining Orthogonally Protected β-d-Idopyranosides

A Scalable Approach to Obtaining Orthogonally Protected β-d-Idopyranosides

Synthesis of a Cycloallin Derivative from β‐Cyclodextrin: Heptakis(2,3‐dideoxy‐2,3‐epithio)‐β‐cycloallin

Synthesis of a Cycloallin Derivative from β‐Cyclodextrin: Heptakis(2,3‐dideoxy‐2,3‐epithio)‐β‐cycloallin

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