Synthesis of conduritols and related compounds

New and stereospecific syntheses for all conduritol isomers have been developed starting from appropriate 1,3-cyclohexadiene derivatives. Oxygen functionalities were introduced by photooxygenation. Application of the ene-reaction of singlet oxygen to 1,4-cyclohexadiene and its derivatives afforded diene system which can be easily trapped by second mol of singlet oxygen to give 49 and 50. Thiourea reduction of the peroxide linkages followed by oxidation gave the corresponding pentol derivatives. Furthermore, reaction of unsaturated endoperoxides with 1.2.4.5-tetraazine derivatives 59-63 afforded new bicyclic endoperoxides with unusual structures.