Studies on the terpenoids and related alicyclic compounds XXXIX. A synthesis of .ALPHA.-methylene-.GAMMA.-lactones fused to medium and large rings by intramolecular cyclization of formylated allyl halides.
Primary and secondary symmetrical diols with 2-10 carbon atoms gave selectively monotetrahydropyranyl ethers in the reaction catalyzed by wet sulfonic acid-type ion-exchange resins in 3,4-dihydro-2H-pyran (DI-IP)/toluene or DHP/hexane. The yields of the monoethers were higher than 80% while those of the corresponding diethers were lower than 5%. In these reactions the rate of the formation of the diethers did not increase much even after most of the diols had been consumed. In the reaction of 1,10-decanediol in DHP/hexane, the yields of the monoether were increased by the addition of DMF or DMSO. Each diol was found to have a particular DHP/hydrocarbon ratio that gave the highest selectivity for the monoether. Generally, the larger the number of carbon atoms of the diols, the smaller the ratio of DHP in the solvents to give high selectivity for the monoether. This method of the selective etherification is quite simple and practical.
Nishiguchi, Takeshi; Kawamine, Katsumi; Ohtsuka, Tomoko, Journal of the Chemical Society. Perkin transactions I, 1992, # 1, p. 153 - 156
1,n-Diols with 3-12 carbon atoms gave selectively the corresponding monotetrahydropyranyl ethers in higher yields than 80% in the reaction catalyzed by hydrogen ion in the water layer which is in contact with DHP-toluene or DHP-hexane layer. (C) 2000 Elsevier Science Ltd. All rights reserved.
NISHITANI, KIYOSHI;ISOZAKI, MASASHI;YAMAKAWA, KOJI, CHEM. AND PHARM. BULL., 38,(1990) N, C. 28-35
作者:NISHITANI, KIYOSHI、ISOZAKI, MASASHI、YAMAKAWA, KOJI