Cyclotrimerization of Enaminones: An Efficient Method for the Synthesis of 1,3,5-Triaroylbenzenes

Abstract

An efficient method for the synthesis of 1,3,5-triaroylbenzenes 2a-f by cyclotrimerization of enaminones 1a-f in acetic acid/pyridine (4:1) is illustrated. The structures of the products have been delineated by spectroscopic methods.

Branched C=C and C−N Bond Cleavage on Enaminones toward the Synthesis of 3‐Acyl Quinolines

“…[13] However,t he most populart ransformation model in such known reactionsa re the condensations initiatedb yt he nucleophilic amino group and/ or the nucleophilic a-C(sp 2 )ÀHb ond. Although other transformations,s uch as C(sp 2 )ÀHc oupling reactions [14] and C=C bond-based cycloaddition reactions, [15] are also occasionally disclosed; the overall diversity of transformationm odelsi ne naminones is not yet abundant.R ecently,w eh ave identified that the C=Cd ouble bond in N,N-disubstituted enaminones is able to undergo af ull cleavage to offer C1 buildingb lock in the construction of pyridines. [16] Under the inspiration of this cleavage model of the C=Cd ouble bond, we envisioned that an alternative synthetic methodf or the synthesis of quinolines might also be designed by employing such bond cleavage as ak ey transformation (Scheme 1).…”

One‐Pot Synthesis of 1,3,5‐Tribenzoylbenzenes by Three Consecutive Michael Addition Reactions of 1‐Phenyl‐2‐propyn‐1‐ones in Pressurized Hot Water in the Absence of Added Catalysts

“…[22] The identities of 1,3,5-tri(p-methylbenzoyl)benzene and 1,3,5-tri(p-chlorobenzoyl)benzene were confirmed by comparing their 1 H NMR spectra with those reported in the literature. [22] The effect of the amount of water on the yield of 1,3,5-tribenzoylbenzene: A series of experiments were performed at 250 8C (10 min) in which the amount of water was adjusted within the molar ratio 0-600 relative to one mole of 1-phenyl-2-propyn-1-one as a starting material. The results are given in the Supporting Information (Table S1) and are summarized in Figure 1.…”

“…[22] 4) The 1 H NMR spectrum showed a singlet at d = 8.47 ppm due to three protons at the 2-, 4-, and 6-positions on the inner benzene ring, multiplets (d = 7.91-7.96 ppm) due to six protons ortho to the carbonyls and remaining multiplets (9 H, d = 7.57-7.71 ppm) due to the three outer benzene rings. [22] The identities of 1,3,5-tri(p-methylbenzoyl)benzene and 1,3,5-tri(p-chlorobenzoyl)benzene were confirmed by comparing their 1 H NMR spectra with those reported in the literature. [22] The effect of the amount of water on the yield of 1,3,5-tribenzoylbenzene: A series of experiments were performed at 250 8C (10 min) in which the amount of water was adjusted within the molar ratio 0-600 relative to one mole of 1-phenyl-2-propyn-1-one as a starting material.…”

The Behavior of 3-Anilinoenone and N-Phenyl Cinnamamide toward Carbon Nucleophiles: Spectroscopy and X-Ray Studies Reveal Interesting New Synthesis Routes to Nicotinonitriles and Tetrahydropyridine-3- Carbonitrile

“…On the other hand, one-pot method involving multicomponent reactions (MCRS) of enaminone 1b, aniline with either malononitrile or ethyl cyanoacetate in refluxing acetic acid or ethanolic piperidine, gave the 1,3,5-triacyl benzene derivatives 19 [36] When enaminones 1b-c was allowed to react with malononitrile in refluxing sodium ethoxide for 6 hours, 2-ethoxy nicotinonitrile derivatives 15 a-b was afforded (Scheme 5). The mass spectra of these compounds revealed a molecular ion peak (M + ) with a m/z value of 230 and 214 respectively.…”