STUDIES ON THE SYNTHESIS OF TETRAHYDROFURAN AND TETRAHYDROPYRAN DERIVATIVES FROM TERPENES .4. CONVERSION OF -1,3-BIS(2-HYDROXYPROPYL)-2,2-DIMETHYLCYCLOPROPANE TO THF AND THP DERIVATIVES

Sulfuric acid-catalyzed rearrangement of diol cis-1 produces a mixture of cis/trans tetrahydrofuranoids 3 and, mainly, trans-configurated te trahydropyranoid 4, which after oxidation yielded a mixture of ketones 5, 6. These ketones were separated and their structures assigned on t he basis of spectral data. It was found that THF derivative 3 is the m ajor rearrangement product of a diastereoisomeric mixture of diol cis- 1, and its high percent ratio in the product is clarified as a result of thermodynamic equilibrium between THF (3) and THP (4) derivatives.