Cyclopropenium-Activated Cyclodehydration of Diols
摘要:
The dehydrative cyclization of diols to cyclic ethers via cyclopropenium activation is described. Using 2,3-diphenylcyclopropene and methanesulfonic anhydride, a series of 1,4- and 1,5-diols are rapidly cyclized to furnish tetrahydrofurans and tetrahydropyrans in high yield. Eleven total substrates are shown, including a gram scale cyclization of a diterpene derivative.
trans-Tetrahydrofurans by OH-Assisted Ru-Catalyzed Isomerization of 2-Butene-1,4-diols
作者:Charles Fehr、Iris Magpantay、Lionel Saudan、Horst Sommer
DOI:10.1002/ejoc.201001166
日期:2010.11
We herein report a general method for the synthesis of 1,2-annulated trans-tetrahydrofurans by the OH-assistedRu-catalyzedisomerization of (Z)-2-butene-1,4-diols (using Chaudret's catalyst), followed by reduction of the incipient lactol (using Et 3 SiH and Amberlyst 15). Alternatively, the lactol can be oxidized to the corresponding lactone (using Ikariya's catalyst). It was shown by labeling experiments