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Sunday, 24 November 2013

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





ARKIVOC 2014 Part (i): Special Issue 'Reviews and Accounts', PG 1-20
Recent advances on diversity oriented heterocycle synthesis via multicomponent tandem reactions based on A3 coupling (14-8183LR) [pp. 1-20]
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 


Full Text: PDF (235K)http://www.arkat-usa.org/get-file/48824/

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.

Conclusions and Outlook

During the last decade, A3
 coupling reaction has evolved to a classical three-component protocol
for accessing various propargylamines. Numerous papers have been published on the
investigation of this synthetic method and spectacular advances on A3
 coupling reactions have
been witnessed in terms of green catalyst system, asymmetric catalysis etc. which also promoted
this coupling protocol as the most preferred option for propargylamine synthesis. From the
perspective of application, the propargylamines possessed broad spectrum of diversity andreactivity, and these compounds could serve as main building blocks in the synthesis of many
organic small molecules. From the perspective of atom economics, devising tandem reactions
based on key transformation of A3
 coupling for the synthesis of more complex and structurally
diverse heterocyclic products in one-pot represent a promising direction in modern organic
synthesis. As introduced in the contents, many elegant results have already been reported on this
area. On the other hand, at current state, this kind of tandem reactions were mainly performed by
using the second functional group in aldehyde, amine or alkyne to initiate subsequent
transformations on propargylamine intermediates, although some reactions using additional
components such as carbon dioxide to design tandem synthesis of heterocyclic products have
also been reported, this kind of examples are still rather rare. Thus, deeper and broader explore is
still demanding since using additional substrates for reactions is theoretically able to provide
considerably higher diversity both in reactions and corresponding products. In addition, versions
of asymmetric catalysis on traditional A3
 coupling have already been accomplished with nice
results, while asymmetric catalysis protocols of A3
 coupling-based tandem synthesis of
heterocycles kept unexplored, more systematic and advanced approaches of asymmetrical
catalysis on these tandem reactions are expected in future.



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Some of the thousands of life-sizeTerracotta Warriors of the Qin Dynasty, ca. 210 BCE

The Great Wall of China was built by several dynasties over two thousand years to protect the sedentary agricultural regions of the Chinese interior from incursions by nomadic pastoralists of the northern steppes


Detail from Along the River During the Qingming Festival, a 12th-century painting showing everyday life in the Song Dynasty's capital city, Bianjing (today's Kaifeng)


Shanghai skyline


The Great Hall of the People in Beijing, where the National People's Congress convenes




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