Synthesis and structure of tetrahydropyrano[2,3-b]-[1,4]dioxines

Article abstract of DOI:10.1002/ardp.19903230202

Under acidic conditions the 6-methoxypyranone 5 and 1,2-ethanediol are converted via the dioxolane 6 to the tetrahydro-cis-pyranodioxinone 7-cis. When 5 is treated with 2-mercaptoethanol and base the thioether 10 is isolated. Acid induced cyclisation of 10 yields the cis- and trans-tetrahydropyrano-oxathiinones 11-cis and 11-trans. Trans-1,2-cyclohexanediol (12) reacts with 5 to the dioxolane derivatives 13 and 14, which can be transformed to the octahydro-trioxa-anthracene derivatives 15 and 16. The ¹H-NMR data show that configuration and conformation of 6 and 7 are in accordance with the pyranodioxane structure in 13 and 15.