General Protocols for the Synthesis of <i>C</i>₂-Symmetric and Asymmetric 2,8-Disubstituted Analogues of Tröger's Base via Efficient Bromine−Lithium Exchanges of 2,8-Dibromo-6<i>H</i>,12<i>H</i>-5,11-methanodibenzo[<i>b</i>,<i>f</i>][1,5]diazocine

Abstract

Methods for facile synthesis of symmetric and unsymmetric functionalized analogues of Tröger's base were developed with use of 2,8-dibromo-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (2) as the starting material. C(2)-symmetric 2,8-disubstituted analogues of Tröger's base (4a-f) were synthesized via double bromine-lithium exchange of 2 followed by quench with electrophiles. Desymmetrization via single bromine-lithium exchange of 2, followed by quench with electrophiles, afforded asymmetric analogues of Tröger's base (6a-g). Further reaction of 2-bromo-8-(trimethylsilyl)-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (6b) produced 7a-c via single bromine-lithium exchange and subsequent quench with electrophiles.