Diazabicycloalkanes with nitrogen atoms in bridgehead positions. - 17. Effect of substituents in benzo[b]-1,4-diazabicyclo[2.2.2]-octene on proton affinity and opening by chloroformate ester

Abstract

The reaction of benzo[1′,2′-b]-1,4-diazabicyclo[2.2.2]octene with chloroformate ester is accompanied by opening of the diazabicyclo fragment and addition of chloroformate ester. A nitro group in the 4′ position lowers the rate constant for opening by 40 times in comparison to the unsubstituted heterocycle, while a 4′ methoxy group practically does not affect the reaction rate. The ratio of the 6- and 7- substituted 1-(β-chloroethyl)-4-ethoxycarbonyl-1,2,3,4-tetrahydroquinoxalines which are formed agrees with a quantum chemical calculation of the proton affinity and indicates a principally inductive effect of the substituents on the reactivity of the heteroatoms. Show more