Improved preparation of (+/-)-(1,3/2,4)-5-cyclohexene-1,2,3,4-tetrol [(+/-)-conduritol-B] and its reaction with hydrobromic and hydrochloric acid; synthesis and characterisation of some (+/-)-1-deoxy-1-halo- and (+/-)- 1,4-dideoxy-1,4-dihalo-conduritols.