Regio- and stereoselective intramolecular hydroalkoxylation of aromatic alkynols: an access to dihydroisobenzofurans under transition-metal-free conditions
Chiral Silver Phosphate Catalyzed Transformation of<i>ortho</i>-Alkynylaryl Ketones into 1<i>H</i>-Isochromene Derivatives through an Intramolecular-Cyclization/Enantioselective-Reduction Sequence
作者:Masahiro Terada、Feng Li、Yasunori Toda
DOI:10.1002/anie.201307371
日期:2014.1.3
The transformation of ortho‐alkynylaryl ketones through a cyclization/enantioselective‐reduction sequence in the presence of a chiral silver phosphate catalyst afforded 1H‐isochromene derivatives in high yield with fairly good to high enantioselectivity. An asymmetric synthesis of the 9‐oxabicyclo[3.3.1]nona‐2,6‐diene framework, which has been found in some biologically active molecules, is presented
Selective cyclization of alkynols and alkynylamines catalyzed by potassium tert-butoxide
作者:Deng Yuan Li、Ke Ji Shi、Xiao Feng Mao、Zheng Le Zhao、Xin Yan Wu、Pei Nian Liu
DOI:10.1016/j.tet.2014.06.078
日期:2014.9
Synthesis of Dihydroisobenzofurans<i>via</i>Palladium-Catalyzed Sequential Alkynylation/Annulation of 2-Bromobenzyl and 2-Chlorobenzyl Alcohols under Microwave Irradiation
作者:Eduardo Buxaderas、Diego A. Alonso、Carmen Nájera
DOI:10.1002/adsc.201400457
日期:2014.11.3
AbstractThe palladium‐catalyzed synthesis of dihydroisobenzofurans has been performed by sequential Sonogashira cross‐coupling/cyclization reactions between terminal alkynes and 2‐(hydroxymethyl)bromo‐ and chlorobenzenes in methanol as solvent at 130 °C under microwave irradiation. A 4,4′‐dichlorobenzophenone oxime‐derived chloro‐bridged palladacycle is an efficient pre‐catalyst to perform this tandem process using 2‐dicyclohexylphosphanyl‐2′,4′,6′‐triisopropylbiphenyl (Xphos) as ancillary ligand and potassium hydroxide as base in the absence of a copper cocatalyst. Under these conditions, functionalized 2‐bromo‐ and 2‐chlorobenzaldehydes are also suitable partners in the domino process affording phthalans in good yields. All the reactions can be performed under air and employing reagent‐grade chemicals under low loading conditions (1 mol% Pd).magnified image