2 research outputs found
Development of Four-Component Synthesis of Tetra- and Pentasubstituted Polyfunctional Dihydropyrroles: Free Permutation and Combination of Aromatic and Aliphatic Amines
We previously reported the novel
efficient proton/heat-promoted
four-component reactions (4CRs) of but-2-ynedioates, two same/different
primary amines, and aldehydes for the <b>s</b>ynthesis of tetra-
and pentasubstituted polyfunctional dihydropyrroles. If aromatic and
aliphatic amines were used as reagents, four different series of products
should be obtained via the permutation and combination of aromatic
and aliphatic primary amines. However, only three/two rather four
different series of tetra-/pentasubstisuted dihydropyrroles could
be prepared via the proton/heat-promoted 4CRs. Herein, CuĀ(OAc)<sub>2</sub>Ā·H<sub>2</sub>O, a Lewis acid being stable in air and
water, was found to be an efficient catalyst for the 4CR synthesis
of all the four different series of tetra-/pentasubstisuted dihydropyrroles.
The copper-catalyzed 4CR could produce target products at room temperature
in good to excellent yields. Interestingly, benzaldehyde, in addition
to being used as a useful reactant for the synthesis of pentasubstituted
dihydropyrroles, was found to be an excellent additive for preventing
the oxidation of aromatic amines with copperĀ(II) and ensuring the
sooth conduct of the 4CRs for the synthesis of tetrasubstituted dihydropyrroles
with aryl R<sup>3</sup>. In addition, salicylic acid was found to
be needed to increase the activities and yields of the copper-catalyzed
4CRs for the synthesis of petasubstituted diyhydropyrroles. On the
basis of experimental results, the enamination/amidation/intramolecular
cyclization mechanism was proposed and amidation is expected to be
the rate-limited step in the copper-catalyzed 4CRs
Development of Four-Component Synthesis of Tetra- and Pentasubstituted Polyfunctional Dihydropyrroles: Free Permutation and Combination of Aromatic and Aliphatic Amines
We previously reported the novel
efficient proton/heat-promoted
four-component reactions (4CRs) of but-2-ynedioates, two same/different
primary amines, and aldehydes for the <b>s</b>ynthesis of tetra-
and pentasubstituted polyfunctional dihydropyrroles. If aromatic and
aliphatic amines were used as reagents, four different series of products
should be obtained via the permutation and combination of aromatic
and aliphatic primary amines. However, only three/two rather four
different series of tetra-/pentasubstisuted dihydropyrroles could
be prepared via the proton/heat-promoted 4CRs. Herein, CuĀ(OAc)<sub>2</sub>Ā·H<sub>2</sub>O, a Lewis acid being stable in air and
water, was found to be an efficient catalyst for the 4CR synthesis
of all the four different series of tetra-/pentasubstisuted dihydropyrroles.
The copper-catalyzed 4CR could produce target products at room temperature
in good to excellent yields. Interestingly, benzaldehyde, in addition
to being used as a useful reactant for the synthesis of pentasubstituted
dihydropyrroles, was found to be an excellent additive for preventing
the oxidation of aromatic amines with copperĀ(II) and ensuring the
sooth conduct of the 4CRs for the synthesis of tetrasubstituted dihydropyrroles
with aryl R<sup>3</sup>. In addition, salicylic acid was found to
be needed to increase the activities and yields of the copper-catalyzed
4CRs for the synthesis of petasubstituted diyhydropyrroles. On the
basis of experimental results, the enamination/amidation/intramolecular
cyclization mechanism was proposed and amidation is expected to be
the rate-limited step in the copper-catalyzed 4CRs