<i>C</i><sub>3</sub>-Symmetric Cinchonine-Squaramide-Catalyzed Asymmetric Chlorolactonization of Styrene-Type Carboxylic Acids with 1,3-Dichloro-5,5-dimethylhydantoin: An Efficient Method to Chiral Isochroman-1-ones
作者:Xin Han、Chune Dong、Hai-Bing Zhou
DOI:10.1002/adsc.201300915
日期:2014.4.14
A more practical and efficient catalytic asymmetricchlorolactonization of styrene‐type carboxylicacids with 1,3‐dichloro‐5,5‐dimethylhydantoin (DCDMH) using C3‐symmetric cinchonine‐squaramide (CSCS) as organocatalyst has been developed. A series of chiral chloro‐substituted isochroman‐1‐ones was obtained in excellent yields (up to 95%) and enantioselectivities (up to 99% ee), whwereby the results
作者:Bayer, Ernst、Hayat, Safdar、Atta-Ur-Rahman、Choudhary, M. Iqbal、Khan, Khalid Mohammed、Shah, Syed Tasadaque Ali、Imran-Ul-Haq、Anwar, M. Usman、Voelter, Wolfgang
DOI:——
日期:——
An Alternative Method for the Synthesis of γ-Lactones by Using Cesium Fluoride-Celite/Acetonitrile Combination
作者:Khan, Khalid Mohammed、Hayat, Safdar、Zia-Ullah、Atta-ur-Rahman、Iqbal-Choudhary、Maharvi, Ghulam Murtaza、Bayert, Ernst
DOI:10.1081/scc-120024003
日期:2003.9
A variety of 2-(1-bromoalkyl) benzoic acids 4 undergo intramolecular nucleophilic substitution reaction when treated with a CsF-Celite as solid base in acetonitrile under reflux condition to give the corresponding cyclized phthalides in moderate to very good yield. These 2-(1-bromoalkyl) benzoic acids 4 are formed by the alpha-bromination of 2-alkylbenzoic acids 3 using N-bromosuccinimide and a catalytic amount of alpha,alpha'-azoisobutyronitrile in carbon tetrachloride under reflux.