Synthesis of chiral bicyclo[2.2.2]oct-5-en-2-ones via an intramolecular alkylation reaction

Abstract

Generation of the thermodynamic dienolate of 9-bromocarvone derivatives 5,7 and 11 furnished the chiral bicyclo[2.2.2]octenones 6, 8 and 9 and 12 and 13 containing a bridgehead methyl group via an intramolecular alkylation reaction. In an analogous manner intramolecular alkylation reaction of the bromo enones 15a–e, obtained from carvone 2 by 1,3-alkylative enone transposition (→14) followed by a regiospecific bromoetherification reaction, furnished the bicyclo[2.2.2]oct-5-en-2-ones 16a–e and 17a–e.