Stereocontrolled Synthesis of Highly Substituted Proline Esters via [3 + 2] Cycloaddition between N-Metalated Azomethine Ylides and Nitroalkenes. Origins of the Metal Effect on the Stereochemical Outcome
摘要:
The [3 + 2] cycloaddition reaction between several N-metalated azomethine ylides and nitroalkenes has been studied using AgOAc and LiClO4 as metalating reagents in the presence of triethylamine. The reaction is found to be very versatile and can be extended to homochiral nitroalkenes. In general, lithium and silver salts promote preferential formation of the endo and exo cycloadducts, respectively. The presence of a phenol moiety induces a shift toward the exo-cycloadduct even when lithium is used. A model based upon the experimental results obtained and SCF-MO calculations is proposed to explain the variable stereochemical outcome of these reactions.
4M lithium perchlorate-nitromethane: An efficient solvent in Diels-Alder reactions using nitroalkenes as dienophiles
作者:Mirari Ayerbe、Fernando P. Cossío
DOI:10.1016/0040-4039(95)00678-6
日期:1995.6
Diels-Alderreactions in which nitroalkenes act as dienophiles are substantially accelerated in 4M lithium perchlorate-nitromethane solutions. This acceleration is higher than that observed when the known 5M lithium perchlorate-diethyl ether system is used.
Stereoselective conjugate addition of carbon nucleophiles to chiral (E)-nitroalkenes bearing a γ-stereocenter. Origins of the observed anti selectivity
作者:Mirari Ayerbe、Iñaki Morao、Ana Arrieta、Anthony Linden、Fernando P. Cossio
DOI:10.1016/0040-4039(96)00468-6
日期:1996.4
The reaction between different organometallic carbonnucleophiles and chiral (E)-nitroalkenes has been studied. Antiselectivities have been observed in all cases. SCF-MO calculations suggest that the observed stereocontrol relies on the anti disposition of a donor group (methyl or hydrogen) with respect to the CC bond in formation.
Stereocontrolled Synthesis of Highly Substituted Proline Esters via [3 + 2] Cycloaddition between N-Metalated Azomethine Ylides and Nitroalkenes. Origins of the Metal Effect on the Stereochemical Outcome
作者:Mirari Ayerbe、Ana Arrieta、Fernando P. Cossío、Anthony Linden
DOI:10.1021/jo971212q
日期:1998.3.1
The [3 + 2] cycloaddition reaction between several N-metalated azomethine ylides and nitroalkenes has been studied using AgOAc and LiClO4 as metalating reagents in the presence of triethylamine. The reaction is found to be very versatile and can be extended to homochiral nitroalkenes. In general, lithium and silver salts promote preferential formation of the endo and exo cycloadducts, respectively. The presence of a phenol moiety induces a shift toward the exo-cycloadduct even when lithium is used. A model based upon the experimental results obtained and SCF-MO calculations is proposed to explain the variable stereochemical outcome of these reactions.
Direct Nucleophilic Acylation of Nitroalkenes Promoted by a Fluoride Anion/Thiourea Combination
作者:Anita E. Mattson、Andrea M. Zuhl、Troy E. Reynolds、Karl A. Scheidt
DOI:10.1021/ja056565i
日期:2006.4.1
carbonyl anion species in situ allow for conjugateadditions in good yield to sensitive nitroalkene electrophiles. The process is tolerant of a variety of thiazolium carbinols and nitroalkene substrates and can be rendered enantioselective and diastereoselective by the addition of a chiral thiourea derivedfrom quinine.