The extent and the regioselectivity of the intramolecular 1,5-hydrogen atom transfer in glycopyranosidic radicals have been studied by deuteration experiments with n-Bu3SnD. Exclusive translocation of the primary cyclized radical 4 to the C(5)-center (in 6) has been observed. Conformational effects are, most probably, governing the ease of the intramolecular hydrogen atom transfer.

keine Beeinträchtigung der Affinität für komplementäre RNA resultiert aus dem Ersatz der natürlichen Phosphodiestereinheiten in Oligonucleotiden durch Amideinheiten. Diese ergaben Untersuchungen von Oligonucleotiden, die einen oder mehrere der modifizierten Bausteine 1 enthielten. Zusätzlich waren diese Oligonucleotide gegenüber 3′‐Exonucleasen nm etwa einen Faktor 10 stabiler. magnified image

No decrease in the affinity for the complementary RNA target is observed when the natural phosphodiester linkages in oligonucleotides are replaced with amide units. This was found in investigations of oligonucleotides containing one or more modified components 1. In addition these oligonucleotides are roughly ten times more resistant towards 3′-exonucleases.

Acyclic α-sulfinyl radicals exhibit high diastereoselectivity in intermolecular as well as interamolecular addition reactions to C=C double bonds. Hydroxylic solvents such as alcohols cause either a loss of diastereoselectivity or have a minor effect as observed in the latter case.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The stereoselective synthesis of 2'-alpha-C-branched nucleosides by a radical addition reaction is described. These new nucleosides were incorporated into oligodeoxyribonucleotides. Measurement of melting temperatures (Tm) of DNA/RNA duplexes and the nuclease resistance of these oligoribodeoxynucleotides are presented.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A regioselective method for the formation of C-centered radicals using an intramolecular 1,5-hydrogen atom transfer from a C(sp3)-H bond to an aryl radical is described. The efficiency of the process depends on conformational effects rather than on the stabilization of the final radical by the adjacent substituents.

AbstractRadical‐induced cyclization of the iodo carbohydrates (I) results in predominant formation of the fused furans (II).

ChemInformVolume 21, Issue 26 Natural Products ChemInform Abstract: Stereoselective C-C Bond Formation in Carbohydrates by Radical Cyclization Reactions. Part 4. Application for the Synthesis of α-C(1)-Glucosides. A. DE MESMAEKER, A. DE MESMAEKER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HOFFMANN, P. HOFFMANN Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorB. ERNST, B. ERNST Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HUG, P. HUG Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorT. WINKLER, T. WINKLER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this author A. DE MESMAEKER, A. DE MESMAEKER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HOFFMANN, P. HOFFMANN Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorB. ERNST, B. ERNST Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HUG, P. HUG Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorT. WINKLER, T. WINKLER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this author First published: June 26, 1990 https://doi.org/10.1002/chin.199026305Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References A. DE MESMAEKER, P. HOFFMANN, B. ERNST, P. HUG, T. WINKLER, Stereoselective C-C Bond Formation in Carbohydrates by Radical Cyclization Reactions. Part 4. Application for the Synthesis of α-C(1)-Glucosides., Tetrahedron Lett., 1989, 30, 6311–6314. 10.1016/S0040-4039(01)93880-8 CASWeb of Science®Google Scholar Volume21, Issue26June 26, 1990 ReferencesRelatedInformation

The stereoselectivity of the 5-exo radical cyclization reaction of allylic 2-deoxy-2-iodoglucopyranosides leading to α-C(2)-branched sugars is influenced by the substitution of the allylic double bond. The observed stereoselectivity for the formation of the chiral center on the newly formed tetrahydrofuran ring results from a less sterically hindered transition state of cyclization, except in the case of a cis phenyl substituted C=C double bond.

ChemInformVolume 21, Issue 26 Natural Products ChemInform Abstract: Stereoselective C-C Bond Formation in Carbohydrates by Radical Cyclization Reactions. Part 3. Strategy for the Preparation of C(1)-Glycosides. A. DE MESMAEKER, A. DE MESMAEKER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HOFFMANN, P. HOFFMANN Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorB. ERNST, B. ERNST Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HUG, P. HUG Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorT. WINKLER, T. WINKLER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this author A. DE MESMAEKER, A. DE MESMAEKER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HOFFMANN, P. HOFFMANN Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorB. ERNST, B. ERNST Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorP. HUG, P. HUG Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this authorT. WINKLER, T. WINKLER Central Res. Lab., Ciba-Geigy Ltd., 4002 Basel, SwitzerlandSearch for more papers by this author First published: June 26, 1990 https://doi.org/10.1002/chin.199026306Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue26June 26, 1990 RelatedInformation

AbstractThe 2‐(haloethyl)glycal ethers (III) and (VIII) undergo radical‐induced cyclization, forming the fused tetrahydrofurans (IV) or (IX).

AbstractThe glycal (I) is converted to the iodinated propargylic ethers (III) which undergo radical‐induced cyclization, forming the bicyclic methylene acetals (IV).

A new strategy for the stereoselective synthesis of α- and β-C(1)-glycosides based on an intramolecular radical cyclization reaction is described. Intramolecular hydrogen atom transfer was observed depending on the concentration of the reagents, the conformation and the substitution of the cyclized radical.

The synthesis of α-C(1)-glucosides is reported using our new strategy for the CC bond formation at the anomeric center by radical cyclization reactions.

A new approach to functionalized 1-O-acyl-β-D-glucuronides is described. An essential element of this strategy is the use of the easily removable allyloxycarbonyl group for the protection of the hydroxylic functions of glucuronic acid.