Microwave-Induced Stereoselective Conversion of Dialkyl 2-(1,1,3-Trioxo-1,3-dihydro-2H-1,2-Benzisothiazol-2-yl)-3-(triphenylphosphoranylidene)succinates to Dialkyl 2-(1,1,3-Trioxo-1,3-dihydro-2H-1,2-benzisothiazol-2-yl)-2-butendioates in the Presence of Silica-Gel Powder in Solvent-Free Conditions
摘要:
Protonation of the highly reactive 1: 1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by saccharin leads to vinyltriphenylphosphonium salts, which undergo an addition reaction with a counter anion in CH2Cl2 at r.t. to produce the corresponding stabilized phosphorus ylides. Silica-gel powder was found to catalyze the stereoselective conversion of the stabilized phosphorus ylides to the corresponding electron-poor N-vinylated isothiazoles in solvent-free conditions under thermal and microwave irradiation in fairly good yields.
Pyridine-Mediated <i>N</i>-Vinylation of Heterocyclic Compounds: A Mild, Stereoselective and General Synthesis
作者:Azam Shahraki、Alireza Hassanabadi
DOI:10.3184/174751914x14112003835373
日期:2014.10
A good yield from the stereoselective synthesis of N-vinylated heterocyclic compounds is described involving the reaction of acetylenicesters and NH heterocyclic compounds in the presence of pyridine. This one-pot method is simple, effective under mild conditions and affords excellent yields.
[image omitted] A diastereospecific synthesis of N-vinyl heterocyclic compounds is described from a reaction of dialkyl acetylenedicarboxylate and N-H heterocyclic compounds, such as phthalimide, saccharin, 3(2H)-pyridazinone, isatin, maleimide, 2,4-thiazolidinedione, 2-benzoxazolinione and 6-chloro-2-benzoxazolinione, in the presence of triphenylarsine as an efficient catalyst, in excellent yield. The presented one-pot method is simple and effective with mild conditions.