A nitrite-catalyzed ring contraction reaction of substituted tetrahydrofurans by oxidation of bromide under aerobic conditions as a dehydrogenative dual functionalization was developed to provide 2-acyltetrahydrofurans in good yields. On the other hand, the oxidation reaction of 1-substituted isochromans occurred via the bromohydroxylation to give 1-(dibromoalkyl)-1-hydroxyisochromans in high yields
A new oxygen-centered radicalcyclization onto silylenolethers has been developed and utilized for the synthesis of versatile siloxy-substituted tetrahydrofurans. The reactions display excellent chemoselectivity for cyclization onto the electron-rich silylenolether when competing terminal alkene cyclization, 1,5-hydrogen abstraction, and beta-fragmentation pathways are present. The increased chemoselectivity
Combined Photoredox and Lewis Acid Catalyzed α-Hydroxyalkylation of Cyclic Ethers with Aromatic Ketones
作者:Melissa Reckenthäler、Jörg-M. Neudörfl、Elif Zorlu、Axel G. Griesbeck
DOI:10.1021/acs.joc.6b01085
日期:2016.8.19
The photochemically induced coupling of aromatic ketones with cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane was studied. Direct photolysis of the substrates with UV-A light centered at 350 nm does not lead to photoinduced hydrogen transfer whereas the addition of a mixture of the Lewis acid catalysts Ti(OiPr)4 and BF3 enables the formation of the hydroxyalkylation products
研究了芳族酮与环醚(如四氢呋喃,四氢吡喃和1,4-二恶烷)的光化学诱导偶联。用居中于350 nm的UV-A光直接对底物进行光解不会导致光诱导的氢转移,而添加路易斯酸催化剂Ti(O i Pr)4和BF 3的混合物能够形成羟烷基化产物。
New method for the synthesis of α-substituted tetrahydrofuran-2-methanols through diastereoselective addition of THF to aldehydes mediated by Et3B in the presence of air
The tetrahydrofuranyl radical, generated from THF with Et3B in the presence of air, was found to react with aldehydes threo-selectively to afford α-substituted tetrahydrofuran-2-methanols, the common structural motifs of biologically active acetogenin polyketides, in moderate yields.
Diastereoselectivite dans la reaction des organomagnesiens sur le tetrahydrofurfural et son gem-diacetate en presence de HMPT. Acces aux diols-1,2 erythro