中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | 3-Allyl-4-[4-(4-chloro-phenoxy)-but-2-ynyloxy]-6-methyl-pyran-2-one | 880135-51-3 | C19H17ClO4 | 344.795 |
—— | 2-Iodomethyl-6-methyl-2,3-dihydro-furo[3,2-c]pyran-4-one | 896132-42-6 | C9H9IO3 | 292.073 |
—— | 6-Methyl-3-(prop-2-en-1-yl)-4-sulfanyl-2H-pyran-2-one | 923602-32-8 | C9H10O2S | 182.243 |
—— | 3-[3-(4-Chlorophenoxy)prop-1-en-2-yl]-8-methyl-2,5-dihydropyrano[4,3-b]oxepin-6-one | 880135-56-8 | C19H17ClO4 | 344.795 |
3-Allyl-4-hydroxycoumarins and 4-allyl-3-hydroxycoumarins are obtained in 90%92% yields by the thermal [3,3] sigmatropic rearrangement of the corresponding ethers. 3-Allyl-4-hydroxy-6-methylpyrone is obtained from the direct alkylation of 4-hydroxy-6-methylpyrone with allyl halide. These substrates on treatment with SnCl4I2 at 25 °C give a mixture of both 5-exo- and 6-endo-cyclization products. However, regioselective formation of 5-exo products is observed when the reactions are conducted at lower temperatures (05 °C, kinetically controlled), while the reaction at a higher temperature (50 °C, thermodynamically controlled) affords regioselectively 6-endo cyclization products.Key words: stannic chloride, iodine, claisen rearrangement, 6-endocyclization, 5-exocyclization, kinetically controlled reaction, thermodynamically controlled reaction.