ipso-vs. tele-Nucleophilic substitution by piperidine on isocolchicides and colchicides bearing an α-leaving group
摘要:
Product studies of the reactions of piperidine with colchicides carrying a C-10 nucleofugic group show that only ipso substitution occurs. For isocolchicides carrying an X nucleofugic group at C-9, similar behaviour was observed for X = F, OTs or OMe, while for X = SMe, SOMe or Cl tele substitution (at C-ll) competes with ipso substitution. These results together with the observation that the reaction rates for the two series are similar, may be useful in guiding the refunctionalization of similar compounds.
ipso-vs. tele-Nucleophilic substitution by piperidine on isocolchicides and colchicides bearing an α-leaving group
摘要:
Product studies of the reactions of piperidine with colchicides carrying a C-10 nucleofugic group show that only ipso substitution occurs. For isocolchicides carrying an X nucleofugic group at C-9, similar behaviour was observed for X = F, OTs or OMe, while for X = SMe, SOMe or Cl tele substitution (at C-ll) competes with ipso substitution. These results together with the observation that the reaction rates for the two series are similar, may be useful in guiding the refunctionalization of similar compounds.