Stereocontrolled Synthesis of <i>Z</i>-Dienes via an Unexpected Pericyclic Cascade Rearrangement of 5-Amino-2,4-pentadienals
作者:Sarah E. Steinhardt、Joel S. Silverston、Christopher D. Vanderwal
DOI:10.1021/ja8028125
日期:2008.6.18
Donor-acceptor dienes known as Zincke aldehydes, which derive readily from the ring-opening reactions of pyridinium salts with secondary amines, undergo a fascinating thermal rearrangement reaction to afford Z-alpha,beta,gamma,delta-unsaturated amides with excellent stereoselectivity. Efficient, stereocontrolled access to Z-trisubstituted alkenes with two different substitution patterns is possible
Microwave-promoted synthesis of chiral pyridinium salts
作者:Gustavo H.R. Viana、Itamar C. Santos、Rosemeire B. Alves、Laurent Gil、Christian Marazano、Rossimiriam P.F. Gil
DOI:10.1016/j.tetlet.2005.09.036
日期:2005.11
The synthesis of several chiralpyridiniumsalts via Zincke’s reaction can be easily accomplished by domestic microwave oven irradiation. Yield enhancements, reduction of reaction time, and less racemization were observed under microwave heating when compared to conventional heating in similar conditions.
Asymmetric synthesis from pyridines: use of new chiral 1,4-dihydropyridines in a short synthesis of 5,8-disubstituted indolizidine (+)-209B
作者:Dino Gnecco、Christian Marazano、Bhupesh C. Das
DOI:10.1039/c39910000625
日期:——
The synthetic potentiality of chiral oxazolidines, prepared from 3-picoline via a 1,4-dihydropyridine intermediate, has been illustrated by an expeditious route to the 5,8-disubstituted indolizidine alkaloid (+)-209B.
Aminopentadiene Imines from Zincke Salts of 3-Alkylpyridines. Application to a Synthesis of Pyridinium Salts from Amino Acids
作者:Tuan Minh Nguyen、Maria del Rayo Sanchez-Salvatori、Jean-Charles Wypych、Christian Marazano
DOI:10.1021/jo0707582
日期:2007.7.1
yields of pyridinium salt than the standard Zincke procedure, it can be advantageous in some cases, as illustrated by the synthesis of pyridiniumsalts from amino acids, a challenging reaction which does not work starting from Zincke salt in the absence of diethylamine. More generally, the reaction can be extended to primary amines featuring polar functions, as exemplified by a pyridinium salt synthesis
5-Aminopenta-2,4-dienals: Synthesis, Activation towards Nucleophiles, Molecular Modeling and Biosynthetic Implications in Relation to the Manzamine Alkaloids
activation of 5-aminopentadienals into electrophilic iminium salts and their subsequent reactivity towards various nucleophiles has permitted the synthesis of a series of unsaturated compounds sometimes accompanied by cascades of rearrangements. Molecular modeling of these systems carried out using DFT calculations of HOMO/LUMO was in agreement with the experimental results indicating that strong electrophilic