Friday 10 January 2014

Recent advances on diversity oriented heterocycle synthesis via multicomponent tandem reactions based on A3 coupling



Recent advances on diversity oriented heterocycle synthesis via multicomponent tandem reactions based on A3 coupling (14-8183LR) [pp. 1-20]
Arkivoc 2014 Part (i), 1-20: Special Issue 'Reviews and Accounts'
Yunyun Liu
Full Text: PDF (235K)
http://www.arkat-usa.org/get-file/48824/
Recent advances on diversity oriented heterocycle synthesis via
multicomponent tandem reactions based on A3 coupling

Yunyun Liu*
a,b

a Key Laboratory of Functional Small Organic Molecule, Ministry of Education,
Jiangxi Normal University, Nanchang 330022, P. R. China
b College of Chemistry and Chemical Engineering, Jiangxi Normal University,
Nanchang 330022, P. R. China

Abstract
A3 coupling reactions are the reactions between aldehydes, amines and alkynes, which yield
propargylamine derivatives under various catalyst conditions. By making use of the versatile
reactivity of propargylamines, tandem reactions initiated by the functional group(s) in the in situ
generated propargylamines constitute one of the most important applications of A3
 couplings.
These tandem reactions are especially useful for the synthesis of heterocyclic compounds. In this
review, the progress on multicomponent tandem reactions based on A3
 coupling is summarized.



Author’s Biography


Dr. Yunyun Liu was born in 1983 in Shandong Province, China. She obtained her Bachelor
Degree in Qufu Normal University in 2005. She then moved to Zhejiang University to continue
her graduate study in the Department of Chemistry. Under the supervision of Professor Weiliang
Bao, she worked on the field of copper-catalyzed Ullmann coupling reaction and related tandem
reactions for her doctorate study. She obtained her doctorate degree in 2010 and presently she is
an assistant professor in Jiangxi Normal University. She is currently interested in the research of
metal-catalyzed organic synthesis and the development of new cascade organic reactions.

Thursday 9 January 2014

Self-contained chemical synthesis



Scientists in the UK have used reactors made on a 3D printer to complete a three stage organic synthesis. The reagents, catalyst and purification step for the synthesis are completely integrated into the chambers of the sealed reactor. When the reactor is rotated, gravity pulls reactants through the different chambers to complete the synthesis.
read all at
http://www.rsc.org/chemistryworld/2013/06/organic-synthesis-reactor-3d-printer

Friday 27 December 2013

A Chemical Tripod


Tripod immobilization of ligands is a simple and flexible strategy for creating new heterogeneous catalysts

A Chemical Tripod

Friday 20 December 2013

Sustainable Synthesis of Phenols




Phenols synthesized within a few minutes in water with a recyclable deep eutectic solvent
Read more

Saturday 14 December 2013

Baeyer-Villiger oxidation

Baeyer-Villiger oxidation

Also known as: Baeyer-Villiger rearrangement

Schematic of the Baeyer-Villiger oxidation. Reagents: ketone, peroxyacid. Product: ester. Comments: The more electron rich group migrates to the oxygen.
The Baeyer-Villiger oxidation is an organic reaction used to convert a ketone to an ester using a peroxyacid (such as mCPBA). The reaction of the ketone with the acid results in a tetrahedral intermediate, with an alkyl migration following to release a carboxylic acid. The more electron rich R group migrates to the oxygen in this concerted process, allowing for accurate prediction of the stereochemistry of the product.[1]
.....................................................................................................................

Mechanism

Mechanism of the Baeyer-Villiger oxidation. Attack with another molecule of peroxyacid followed by deprotonation. As a positive charge is forming on the labeled oxygen (as the carbonyl group abstracts a proton from the acid), the more electron rich R group migrates to the oxygen to stabilize it.

.......................................................................

References:

1.
Baeyer, A.; Villiger, V. Ber. Dtsch. Chem. Ges. 189932, 3625–3633.

Tuesday 10 December 2013

Supercritical Carbon Dioxide: A Promoter of Carbon–Halogen Bond Heterolysis


Thumbnail image of graphical abstract

Angewandte Chemie International Edition

Volume 52Issue 50pages 13298–13301December 9, 2013

Thais Delgado-Abad, Dr. Jaime Martínez-Ferrer, Prof. Dr. Ana Caballero, Dr. Andrea Olmos, Prof. Dr. Rossella Mello, Prof. Dr. María Elena González-Núñez, Prof. Dr. Pedro J. Pérez and Prof. Dr. Gregorio Asensio
Article first published online: 15 OCT 2013 | DOI: 10.1002/anie.201303819

Amazing reaction medium: Supercritical carbon dioxide, with zero dipole moment, lower dielectric constant than pentane, and non-hydrogen-bonding behavior, ionizes carbon–halogen bonds, dissociates the resulting ion pairs, and escapes from capture by the carbocation intermediates at temperatures above 40 °C. These properties allow the observation of carbocation chemistry in the absence of acids.