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Copper-Catalyzed Highly Efficient Multicomponent
Reactions:Synthesis of quinolin-2(1H)-imine
1
She Debing, Yang Mingyu, Hui Haohao, Zhao Qin, Chen Min, Huang Guosheng
*
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou(730000)
E-mail:hgs2368@163.com
Abstract
A variety of substituted quinolin-2(1H)-imine are prepared via a copper-catalyzed multicomponenet
reaction of sulfonyl azides, terminal alkynes, and o-aminobenzaldehyde. First sulfonyl azides, alkynes
under the copper catalysis condition build the intermediate, then o-aminobenzaldehyde
dehydrogenation under Et
3
N condition and attact the intermediate to form the quinolin-2(1H)-imine.
Keywords: sulfonyl azides, alkynes, o-aminobenzaldehyde, multicomponent reactions,
quinolin-2(1H)-imine
The prominence of quinolin-2(1H)-one in natural product sand biologically active molecules has
promoted considerable efforts toward their synthesis
1
. As a “privileged” scaffold, quinolin-2(1H)-one
shows interesting biological properties
2
. A number of quinolin-2(1H)-one possess interesting biological
activity, including anticancer, antifungal, and anti-HIV activities. Quinolin-2(1H)-one derivatives
quinolin-2(1H)-imine also have been reported to be a type of anticancer, antifungal, and anti-HIV
active compounds.
Multicomponent reactions (MCRs) involving a domino process with at least three different simple
substrates have emerged as a powerful strategy
3
.This methodology allows molecular complexity and
diversity to be created by the facile formation of several new covalent bonds in a one-pot
transformation quite closely approaching the concept of an ideal synthesis and is particularly
well-adapted for combinatorial synthesis
4
.The MCR (multicomponent reaction), offering an efficient
route to generate complex molecular frameworks from simple and readily available substrates, is a
powerful tool in modern organic synthesis as well as in the field of combinatorial chemistry and drug
discovery
5
.Although little attention was paid to the novel MCRs in the second half of the last century,
they have naturally become a rapidly evolving research area and have attracted the attention of both
academic and industrial scientists in the past few years. Among them, the transition-metal-catalyzed
MCRs are of high importance because they have excellent catalytic efficiency in most cases
6
.
More recently, Chang et al. reported several CuI-catalyzed muticomponent reactions of sulfonyl azides
with alkynes as well as amines, water, alcohol, or imines produced N-sulfonylamidines, hydratuve
amides, N-sulfonylimidates, N-sulfonylazetidin-2-imines in good yields, respectively, and with
salicylaldehydes or carbodiimides as the third component, the three-component reactions generated
iminocoumarins and 2-(sulfonylimino)-4-(alkylimino) azetidine derivatives also in good
yields ,respectively
7
. As a part of our research program aiming at new approaches to diverse aromatic
ring systems
8
, we developed a novel synthesis of substituted quinolin-2(1H)-imine via a CuI-catalyzed
multicomponent reaction of sulfonyl azides with alkynes and o-aminobenzaldehyde.
1
The authors thank State Key Laboratory of Applied Organic Chemistry for financed support