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
作者:Marino Cavazza、Francesco Pietra
DOI:10.1039/p19950002657
日期:——
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.
Simplified, high-yield regioselective synthesis of 10-aminocolchicides and 2-aminotropones
作者:Marino Cavazza、Francesco Pietra
DOI:10.1016/0040-4039(95)00499-3
日期:1995.5
Treatment of colchiceine with BF3OEt2, followed by evaporation, addition of DMSO and a secondary amine like piperidine, or sterically hindered like 2-methylpiperidine, was found to result in rapid, quantitative replacement of the hydroxyl group at C-10 or C-9 by the amine to give the 10-aminocolchicide/9-aminoisocolchicide or with high regiospecificity for 10-aminocolchicide; the products could be