Manganese(III)-mediated oxidative free-radical cyclisations of allenyl malonates
作者:Lucy Curry、Michal S. Hallside、Luke H. Powell、Simon J. Sprague、Jonathan W. Burton
DOI:10.1016/j.tet.2009.09.112
日期:2009.12
The regioselective synthesis of alkenylcyclanones by the oxidative radical cyclisation of malonyl radicals onto both allenes and an allylsilane is reported, along with the diastereoselective formation of [3.3.0]-bicyclic γ-lactones from two of these alkenylcyclanones. Furthermore, the cyclisation of 3-, 4- and 5-allenyl malonates on exposure to manganese(III) acetate under both oxidative and reductive
Pd-Catalyzed Cascade Cyclization by Intramolecular Heck Insertion of an Allene–Allylic Amination Sequence: Application to the Synthesis of 3,4-Fused Tricyclic Indoles
A novel Pd-catalyzed cascade cyclization by intramolecular Heck insertion of an alleneallylic amination sequence was developed. Allenes tethered to ortho-iodoaniline derivatives at the meta-position were reacted with 5-10 mol % of Pd catalyst and 4 equiv of K2CO3 in DMSO at 90 degrees C, producing 3,4-fused tricyclic 3-alkylidene indoline derivatives in moderate to excellent yield. The reaction products were divergently transformed into three types of 3,4-fused tricyclic indole derivatives, successfully demonstrating the versatile properties of the reaction products.
Alkaline metallic reagent-catalyzed hydrocarbocyclization reaction ofvarious active methine compounds having an unactivated 4-alkynyl or allenyl group
On using a catalytic amount of NaH or n-BuLi, hydrocarbocyclization;reaction of various active methine compounds having an unactivated 4-pentynyl or 3,4-pentadienyl group proceeded through proton transfer mechanism to give methylenecyclopentane derivatives in good yields. (C) 1999 Elsevier Science Ltd. All rights reserved.