scholarly journals Steric Control in Ring-Opening Polymerization of 1,6-Anhydro Galactose Derivatives by Neighboring Group Participation

1993 ◽  
Vol 25 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Kazukiyo Kobayashi ◽  
Takahiro Ishii ◽  
Masahiko Okada ◽  
Conrad Schuerch
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation ◽  
Steric Control

Living ring-opening polymerization based on neighboring group participation

2000 ◽  
Vol 157 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Takeshi Endo ◽  
Fumio Sanda ◽  
Wonmun Choi
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation

Sterically controlled ring-opening polymerization of an 1,6-anhydro-.beta.-D-galactopyranose derivative by neighboring group participation. (1 .fwdarw. 6)-.beta.-D-Galactopyranan

1988 ◽  
Vol 21 (2) ◽  
pp. 542-543 ◽  
Author(s):  
Kazukiyo Kobayashi ◽  
Haruo Ichikawa ◽  
Hiroshi Sumitomo ◽  
Conrad Schuerch
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation

Synthesis of a β-(1→6)-linked polysaccharide via ring-opening polymerization with neighboring-group participation

1988 ◽  
Vol 179 ◽  
pp. 315-320 ◽  
Author(s):  
Haruo Ichikawa ◽  
Kazukiyo Kobayashi ◽  
Hiroshi Sumitomo ◽  
Conrad Schuerch
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation

Neighboring-group participation in benzylidene acetal ring-opening of a 2-cyano-2-deoxypyranoside derivative by diethylaluminum cyanide

2003 ◽  
Vol 338 (21) ◽  
pp. 2177-2183 ◽  
Author(s):  
Marı́a I Mangione ◽  
Alejandra G Suárez ◽  
Rolando A Spanevello
Keyword(s):  
Ring Opening ◽  
Neighboring Group ◽  
Group Participation ◽  
Neighboring Group Participation ◽  
Acetal Ring

Neighboring group participation in hypobromous acid addition to 19-substituted 5α-cholest-1-enes and in acid cleavage of their epoxy analogs

1982 ◽  
Vol 47 (11) ◽  
pp. 3062-3076 ◽  
Author(s):  
Václav Černý ◽  
Pavel Kočovský
Keyword(s):  
Neighboring Group ◽  
Group Participation ◽  
Acid Addition ◽  
Acid Cleavage ◽  
Hypobromous Acid ◽  
Neighboring Group Participation

Reactions of the title compounds (bearing an OH, OCH3 or OCOCH3 group at C(19)) involve 5(O)n, 7(O)π,n-participation by the 19-substituent or attack by an external nucleophile. The 6(O)π,n-participation does not occur. The behavior of 1,2-unsaturated (or epoxidated) compounds has been compared with the earlier described 2,3-unsaturated or epoxidated analogs. The 1,2-type is genarally less prone to participation. The reasons for this behavior are discussed.

Mechanism of acid cleavage of some steroid epoxides. Competition between neighboring group participation and external nucleophile attack

1982 ◽  
Vol 47 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Pavel Kočovský ◽  
František Tureček ◽  
Václav Černý
Keyword(s):  
Perchloric Acid ◽  
Cyclic Ether ◽  
Oxirane Ring ◽  
Neighboring Group ◽  
Group Participation ◽  
Acid Cleavage ◽  
Neighboring Group Participation

The mechanism of perchloric acid cleavage of epoxides I and II was established on the basis of experiments using H2 18O. The 2α,3α-epoxide I gave two products: the cyclic ether V (60%) arising by 5(O)n participation of the 19-acetoxyl and the diol VI (40%). The latter compound is formed by two mechanisms: 1) By direct cleavage of the oxirane ring with H2 18O as external nucleophile and 2) by 7(O)π,n participation via the ion III. Under the same conditions the 5α,6α-epoxide II yielded two diols: The diequatorial diol VIII (96%) arising by 6(O)π,n participation and the diaxial diol IX which is again formed by both direct cleavage of the oxirane ring with H2 18O and by 7(O)π,n participation via the intermediate ion X. The competition of several mechanisms is discussed.

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