1,3-syn-Diaxial Repulsion of Typical Protecting Groups Used in Carbohydrate Chemistry in 3-O-Substituted Derivatives of Isopropyl d-Idopyranosides

2017 ◽  
Vol 82 (17) ◽  
pp. 8897-8908 ◽  
Author(s):  
Bozhena S. Komarova ◽  
Alexey G. Gerbst ◽  
Anastasiia M. Finogenova ◽  
Andrey S. Dmitrenok ◽  
Yury E. Tsvetkov ◽  
...  
Keyword(s):  
Protecting Groups ◽  
Carbohydrate Chemistry ◽  
Derivatives Of

Bis(ether) derivatives of tetrakis(2-hydroxyphenyl)ethene — Direct synthesis of (E)- and (Z)-bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene via the McMurry olefination reaction

2006 ◽  
Vol 84 (10) ◽  
pp. 1250-1253 ◽  
Author(s):  
Mee-Kyung Chung ◽  
Paul Fancy ◽  
Jeffrey M Stryker
Keyword(s):  
Supramolecular Chemistry ◽  
Direct Synthesis ◽  
Protecting Groups ◽  
Tert Butyl ◽  
Orthogonal Protection ◽  
Protection Strategies ◽  
Titanium Trichloride ◽  
Sterically Hindered ◽  
Derivatives Of

The direct synthesis of sterically hindered, partially etherified derivatives of tetrakis(2-hydroxyphenyl)ethene is reported by using the McMurry reductive olefination reaction on a range of differentially substituted 2,2′-dialkoxy benzophenone substrates. Three orthogonal protection strategies are demonstrated, incorporating β-silylethyl, 3-butenyl, and tert-butyl protecting groups, respectively, into the starting benzophenones. The latter proved most efficient, with both the McMurry coupling and deprotection steps occurring concomitantly under the McMurry conditions to directly yield the desired bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethene as a 1:1 mixture of E- and Z-diastereoisomers.Key words: preorganized polyaryloxide ligands, McMurry olefination, titanium trichloride, supramolecular chemistry, tetrakis(2-hydroxyphenyl)ethene, 2,2′-disubstituted benzophenone.

Protecting Groups in Carbohydrate Chemistry

1997 ◽  
Vol 74 (11) ◽  
pp. 1297 ◽  
Author(s):  
Sigthór Pétursson
Keyword(s):  
Protecting Groups ◽  
Carbohydrate Chemistry

scholarly journals Pyrimidine N-oxides. IV. The N,N'-dihydroxy derivatives of phenobarbital and veronal

1982 ◽  
Vol 35 (4) ◽  
pp. 795 ◽  
Author(s):  
W Cowden ◽  
NW Jacobsen
Keyword(s):  
Protecting Groups ◽  
Derivatives Of

5-Ethyl-1,3-dihydroxy-5-phenylbarbituric acid (N,N'-dihydroxyphenobarbital) and 5,5-diethyl-1,3-dihydroxybarbituric acid (N,N'-dihydroxyveronal) have been prepared by the condensation of 1,3-dibenzyloxyurea with ethylphenylmalonyl dichloride and diethylmalonyl dichloride respectively, followed by the removal of the benzyl protecting groups from the intermediate dibenzyloxy derivatives.

Introduction of 9-fluorenylmethyloxycarbonyl, trichloroethoxycarbonyl, and benzyloxycarbonyl amine protecting groups into O-unprotected hydroxyamino acids using succinimidyl carbonates

1982 ◽  
Vol 60 (8) ◽  
pp. 976-980 ◽  
Author(s):  
Alenka Paquet
Keyword(s):  
Benzyl Ester ◽  
Protecting Groups ◽  
Efficient Conversion ◽  
Hydroxyamino Acids ◽  
High Yields ◽  
Derivatives Of ◽  
Acid Esters ◽  
Efficient Reagent

9-Fluorenylmethyl succinimidyl, pentachlorophenyl, and benzotriazole-1-yl carbonates were prepared and their reactivity with L-serine and L-serine benzyl ester was compared. The most efficient reagent, 9-fluorenylmethyl succinimidyl carbonate, was used for the preparation of 9-fluorenylmethyloxycarbonyl derivatives of other hydroxyamino acids and hydroxyamino acid esters in high yields. The use of trichloroethyl and benzyl succinimidyl carbonates for an efficient conversion of hydroxyamino acids and their esters into the corresponding N-trichloroethoxycarbonyl and benzyloxycarbonyl derivatives is described.

ChemInform Abstract: Protecting Groups in Carbohydrate Chemistry Profoundly Influence All Selectivities in Glycosyl Couplings

ChemInform ◽  
2008 ◽  
Vol 39 (26) ◽  
Author(s):  
Bert Fraser-Reid ◽  
K. N. Jayaprakash ◽  
J. Cristobal Lopez ◽  
Ana M. Gomez ◽  
Clara Uriel
Keyword(s):  
Protecting Groups ◽  
Carbohydrate Chemistry

Preparation of 2'(3')-O-phosphonylmethyl derivatives of ribonucleosides

1983 ◽  
Vol 48 (3) ◽  
pp. 778-789 ◽  
Author(s):  
Ivan Rosenberg ◽  
Antonín Holý
Keyword(s):  
Alkali Metal ◽  
Metal Hydride ◽  
Sodium Hydride ◽  
Protecting Groups ◽  
Aqueous Alkali ◽  
Subsequent Hydrolysis ◽  
Derivatives Of ◽  
Alkali Metal Hydride

Reaction of 5'-O-tritylribonucleosides I with dimethyl p-toluenesulfonyloxymethanephosphonate (III) followed by hydrolysis afforded 2'(3')-O-phosphonylmethyluridine (IIa), -cytidine (IIb) and -adenosine (IIc). With 2',5'-di-O-trityluridine (IX), this procedure led to the 3'-isomer of IIa, with 3',5'-di-O-trityluridine (X) to the 2'-isomer. 5'-O-Trityluridine (Ia) and -cytidine (Ib) were converted by reaction with iodomethanephosphonic acid and N,N'-dicyclohexylcarbodiimide into the 2'(3')-O-iodomethanephosphonyl derivatives IVa, b which on reaction with sodium hydride and subsequent hydrolysis gave the compounds IIa and IIb. Reaction of compound I or 5'-O-benzoyluridine (VIII) with chloromethanephosphonyl dichloride (V) and removal of the protecting groups afforded 2'(3')-O-chloromethanephosphonylribonucleosides VI which on reaction with sodium hydride, or better with aqueous alkali, gave 2'(3')-O-phosphonylmethyl derivatives of uridine (IIa), cytidine (IIb), adenosine (IIc) and guanosine (IId). 2',3'-O-Isopropylideneribonucleosides XI reacted with the compound V to give, after hydrolysis, 5'-O-chloromethanephosphonyluridine (XIIa) and cytidine (XIIb). These compounds were not affected by an alkali metal hydride or hydroxide.

Approaches to the preparation of 3'-deoxynucleosides

1968 ◽  
Vol 21 (2) ◽  
pp. 513 ◽  
Author(s):  
GAR Johnston
Keyword(s):  
Acyl Migration ◽  
Protecting Groups ◽  
Nucleophilic Displacement ◽  
Iodination Reaction ◽  
Catalytic Hydrogenolysis ◽  
The Stability ◽  
Derivatives Of

The stability of 3'-O-sulphonyl derivatives of uridine towards nucleophilic displacement indicates that sulphonate replacement is unlikely to offer a general route to 3'-deoxynucleosides. The preparation of 3'-deoxyuridine by direct iodination of 2',5'-di-O-trityluridine with triphenylphosphite methiodide followed by catalytic hydrogenolysis is discussed as such a general route dependent on the availability of suitably protected nucleoside starting materials. Acyl migration takes place under the conditions of the iodination reaction, limiting the choice of protecting groups.

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