Metal-free homoallylic oxygen-directed intramolecular hydroboration is reported. Regioselectivities from 20:1 to 82:1 favoring the 1,3-dioxy-substituted products have been achieved using Me2S center dot BH3/TfOH followed by standard oxidative workup. Branching at the C5 position improves regioselectivity.
mild method is reported for the construction of β-chlorotetrahydrofuran derivatives by 5-endo chlorocycloetherification of homoallylic alcohols. The system employs sulfurylchloride as the chlorinating agent under catalyst-free conditions. A variety of homoallylic alcohols with aryl or alkyl substituents were smoothly converted into β-chlorotetrahydrofurans in yields up to 98%. An efficient and mild method
Copper-Catalyzed Diastereoselective Synthesis of Trifluoromethylated Tetrahydrofurans
作者:Yanan Wang、Min Jiang、Jin-Tao Liu
DOI:10.1002/adsc.201501166
日期:2016.4.14
The copper‐catalyzed intramolecular diastereoselective trifluoromethylcycloetherification of homoallylic alcohols with Togni’s reagent as trifluoromethylating reagent was realized under mild conditions. Various trifluoromethylated tetrahydrofurans were synthesized in moderate to good yields. Moreover, a wide range of common functional groups was tolerated.
Regioselective, Asymmetric Formal Hydroamination of Unactivated Internal Alkenes
作者:Yumeng Xi、Trevor W. Butcher、Jing Zhang、John F. Hartwig
DOI:10.1002/anie.201509235
日期:2016.1.11
We report the regioselective and enantioselective formalhydroamination of unsymmetrical internalalkenes catalyzed by a copper catalyst ligated by DTBM‐SEGPHOS. The regioselectivity of the reaction is controlled by the electronic effects of ether, ester, and sulfonamide groups in the homoallylic position. The observed selectivity underscores the influence of inductive effects of remote substituents
Substituted tetrahydrofuran derivatives play important roles as biological activities. A versatile method for the synthesis of beta-phosphonotetrahydrofurans has been developed based on Cu-catalyzed difunctionalization of alkenes. This transformation would provide a new pathway for the formation of Csp(3)-P and Csp(3)-O bonds in one step. Furthermore, this copper catalyst system can be used in the synthesis of beta-phosphonotetrahydropyrans and phosphono-gamma-butyrolactones. These reactions were also performed well by using 3 equiv of Mn(OAc)(3)center dot 2H(2)O as the oxidant without copper catalyst.