Health & Environmental Research Online (HERO)


Print Feedback Export to File
7439976 
Journal Article 
STEREOSELECTIVE EPOXIDATION OF ALLYLIC CARBAMATES WITH M-CHLOROPERBENZOIC ACID - THE ROLE OF COOPERATIVE COORDINATION 
Ney, JF; Sasner, JJ; Ikawa, M; Jenmalm, A; Berts, W; Luthman, K; Csoregh, I; Hacksell, U 
1995 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
60 
1026-1032 
English 
Stereoselective epoxidations of a series of allylic carbamate methyl esters la-d, homoallylic alcohols le-h, and acetates li-1 have been performed using m-chloroperbenzoic acid (m-CPBA) as epoxidizing agent. Throughout, the formation of the threo epoxides was favored. This selectivity is probably due to a directing effect of the carbamate group which forms a hydrogen bond to the peracid. However, the threo/erythro isomeric ratio is also dependent on steric interactions and on the possibility of cooperative coordination of the peracid to other suitably positioned functionalities such as allylic methyl ester, homoallylic alcohol, and acetate groups. The results of the present study indicate that the methyl ester is a weaker directing group than the carbamate. However, the directing effect of the methyl ester is stronger than that of the homoallylic alcohol and acetate groups. A thermodynamic study of the epoxidation of two epimeric carbamate esters giving considerably different isomeric product ratios (9:1 compared to 2:1) indicates that the order in the transition state structure influences the isomeric ratios. © 1995, American Chemical Society. All rights reserved. 
Other
• Harmful Algal Blooms- Health Effects
     April 2021 Literature Search
          WOS
          Scopus
          Saxitoxins
               WOS