Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

5(O)ⁿ and 6(O)^π,n participations by some oxygen containing functional groups in the course of reaction with hypobromous acid have been studied on olefinic models of steroid type (I and II). The ability of these groups to participate has been compared on the basis of their relative reactivity with water (as externally attacking nucleophile) competing with participation. The results of the product analysis show that the ability to react with 5(O)ⁿ participation decreases in the order HO > CH₃O ≃ CH₃OCH₂O > CH₃CO₂ > HCO₂ > CH₃SO₃ ≥ (C₂H₅O)₂PO₂ > C₆H₅CO₂ > O₂NO ≫ CF₃CO₂, C₂H₅OCO₂; in the last two functional groups is this ability completely suppressed. The 6(O)^π,n participation comes in consideration only for compounds of the type II bearing the groups with the -X=O moiety which are ordered in the following sequence: C₂H₅OCO₂ ≃ CH₃CO₂ ≥ (C₂H₅O)₂PO₂ > HCO₂ > C₆H₅CO₂. The remaining functional groups (CF₃CO₂, O₂NO and CH₃SO₃do not undergo this process. Generally, it is valid that introduction of electron-withdrawing substituents into a participating group impedes or completely suppresses its ability to participate.