The crystal structures of six polybromo carvones

Abstract

The crystal structures of six polybromo carvones have been determined by single-crystal X-ray diffraction. These are the three previously reported isomeric tetrabromo carvones, (1S,3S,4R,8R)-1,3,8,9-tetrabromo-p-menthan-2- one (4), (1S,3S,4R,8S)-1,3,8,9-tetrabromo-p-menthan-2-one (5) and (1R,3S,4R,8R)-1,3,8,9-tetrabromo-p-menthan-2-one (12), two tribromo derivatives, (1S,4R,8R)-1,8,9-tribromo-p-menthan-2-one (10) and (1S,4R,8S)-1,8,9-tribromo-p-menthan-2-one (11) [all derived from (R)-carvone (1)], together with a pentabromo derivative, (1S,3S,4R,6R,8R)-1,3,6,8,9-pentabromo-p-menthan-2-one (7) [derived from (S)-carvone ent-(1)]. In all examples, the stereochemistry agrees with that predicted from the synthetic pathway, while with one [the (1R,3S,4R,8R)-tetrabromide (12)] a distorted twist-chair conformation is found.