Organic compounds containing the cyclic ether skeltons tetrahydrofuran (THF) or tetrahydropyran (THP) are widely found in nature. In addition, they are also found as partial pyrolysis products of carbohydrates, Some THF and THP derivatives display characteristics of biological activity The introduction of THF and THP structural elements into analgesics, saluretics and antibiotics maybe considered as a curious discovery in this regard. Some THF-didesoxynucleosides are being studied recently as potential anti-HIV agents.
During the last three decades, due to improved analytical methods, a number of tetrahydrofuranoids and tetrahydropyranoids have been isolated from plant extracts. It has been found that they are essential microcomponents of many plants (Table I) because of their high aroma value.
The importance of cyclic ethers as flavor and perfumery compounds is continually growing. This evolution originated with the two diastereoisomeric rose oxides which, after their discovery in rose and geranium oils, followed by their synthetic accessibility, are now among a group of most appreciated perfumery raw materials. Besides, at least three other cyclicethers (nerol oxide, 2,26-trimethyl-6-vinyltetrahydropyran and dihydro rose oxide) have become commercially available.