Cationic Ring-Opening Polymerization of Cyclic Monothiocarbonates:  Varying the Polymer Main Chain by Neighboring Group Participation

2001 ◽  
Vol 34 (22) ◽  
pp. 7642-7647 ◽  
Author(s):  
Nobukatsu Nemoto ◽  
Xiaoyu Xu ◽  
Fumio Sanda ◽  
Takeshi Endo
Keyword(s):  
Ring Opening ◽  
Main Chain ◽  
Ring Opening Polymerization ◽  
Neighboring Group ◽  
Group Participation ◽  
Polymer Main Chain ◽  
Cationic Ring Opening Polymerization ◽  
Neighboring Group Participation

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.

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