Remarkable selectivity in addition of alcohols to epoxydienes of 5,7 bicyclic and 5,7,6 tricyclic systems
(Chemical Equation Presented) Acid-catalyzed addition of alcohols to tricyclic dienyl epoxides such as 4 or bicyclic vinyl oxiranes such as 17 exclusively occurred at the vinyl terminus of unsaturated system through a typical SN2′ process affording 1,6- and 1,4-dioxygenated derivatives, respectively.
Studies on the molecular toxicology of buta-1,3-diene and isoprene epoxides
Reactions of ethenyloxirane with amino (RNH2) and thiol (R'SH) nucleophiles occur by an S(N)2 mechanism involving competing ring cleavage at C-2 and C-3. In contrast, 2-ethenyl-2-methyloxirane reacts with amino (RNH2) and thiolate (R'S+) nucleophiles in methanol by regioselective S(N)2 attack at C-3 ('neo-pentyl' position). However, in pure water or methanol S(N)1 reaction occurs mainly at C-2.
Bleasdale, Christine,Small, Rowena D.,Watson, William P.,Wilson, Joanne,Golding, Bernard T.