Reversible ArSE aroylation has been observed in the reaction of 2,7-dimethoxynaphthalene (1) with 4-chlorobenzoic acid/acid chloride 2 with the aid of discrete acidic mediators. The reaction readily gives 1-aroylated-, 3-aroylated-, and 1,8-diaroylated products. The product distribution clearly shows dependence on the kind and strength of the acidic mediators and the time-course of the distribution manifests dearoylation of the productive aroylnaphthalenes. These reaction behaviors including acid-strength-dependent reversibility are well interpreted from the viewpoint of highly congested noncoplanar geometry of the polyaromatic ketone products.
The molecule of the title compound, C26H20O4, is located on a twofold rotation axis. The two benzoyl groups are situated in an anti orientation. The dihedral angle between the mean planes of the phenyl ring and the naphthalene ring system is 80.25 (6)°. The phenyl and carbonyl groups in each benzoyl group are almost coplanar. The molecular packing is stabilized by weak C—H⋯O hydrogen bonds and a π–π stacking interaction between the phenyl rings [centroid–centroid and interplanar distances of 3.6383 (10) and 3.294 Å, respectively].
Dual ArSE aroylation of 2,7-dimethoxynaphthalene proceeds with distinct susceptibility and regioselectivity depending on the Lewis acid. The TiCl4-mediated reaction readily affords 1,8-diaroylated product. In the AlCl3-mediated reaction, monoaroylation essentially proceeds with partial ether cleavage and under some specific conditions 1,6-diaroylation proceeds in preference to 1,8-diaroylation.
In the title compound, C19H15ClO3, the dihedral angle between the naphthalene ring system and the benzene ring is 72.06 (7)°. The 4-chlorophenyl group and the carbonyl group are almost coplanar. An intermolecular C—H⋯O hydrogen bond is formed between an H atom of the 4-chlorophenyl group and the O atom of one methoxy group, forming a zigzag chain along the a axis.
Thermally irreversible photochromic 1-tert-butyl-substituted 2,3-bisthiazolylindenol has been synthesized. It showed perfect diastereoselectivity and high ring-closing quantum yield with high conversion ratio to the closed form. The collaborative interaction of two intramolecular hydrogen bonds and the steric restriction fixed the conformation in favour of cyclization in a highly diastereoselective manner.
The asymmetric unit of the title compound, C19H16O3, contains three independent conformers. Each of the three conformers has essentially the same feature of non-coplanar aromatic rings whereby the aroyl group at the 1-position of the naphthalene ring is twisted in a perpendicular manner to the naphthalene ring. The dihedral angles between the benzene ring planes and the naphthalene ring systems are 75.34 (7), 86.47 (7) and 76.55 (6)° in the three conformers. The crystal structure is stabilized by intermolecular C—H⋯O hydrogen bonds.
The title compound, C26H18F2O4, is a naphthalene derivative in which the two aroyl groups at the 1- and 8-positions (peri positions) are anti to each other. There is an appreciable difference in the dihedral angles between the naphthalene ring system and the two benzene rings [66.88 (7)° and 88.09 (6)°]. In the crystal, weak C—H⋯O interactions involving one of the carbonyl groups and an aromatic C—H group ortho to the F atom seem to stabilize the packing of the molecules.
The structural design strategy and the synthetic approaches for the wholly aromatic polyketones and the monomers are described. Electrophilic aromatic aroylation substitution polycondensation and aromatic coupling polycondensation have been investigated as synthetic routes for wholly aromatic polyketones by the author's group. Acyl-acceptant arene molecules as the electrophilic aromatic aroylation substitution polycondensation type monomers and the aromatic nuclei for bis(chlorobenzoylated) compounds as the aromatic coupling polycondensation one were designed and synthesized employing 2,2 0 -dioxybiphenyl, 2,2 0 -dioxy-1,1-binaphtyl, and o-terphenyl skeletons. Determining factors for monomers, which enable regioselective polycondensation, are also discussed. The properties of polyketones are also discussed briefly on the basis of polymer repeating unit structures. Aromatic polyketones are a group of aromatic polymers having ketonic carbonyl groups as the major linkage in the aromatic polymer main chain. Though there have been reported many examples of aromatic polyketones, almost all of them belong to the category of ''aromatic poly(ether ketone)s.'' [1][2][3][4][5] In fact, the term ''aromatic polyketone'' is generally apt to be regarded identical to ''aromatic poly(ether ketone).'' As a representative material of this category of aromatic polymer, PEEK Ò (1), a poly(ether ether ketone), is well-known super engineering plastics showing superior thermal stability, mechanical strength, and chemical resistance. Figure 1 shows the structure of PEEK Ò (1). The repeating unit of the polymer is composed of three 1,4-phenylene moieties bonded with two ether linkages and one ketonic carbonyl group. The structure suggests that PEEK Ò (1) might have properties more attributable to aromatic ether rather than aromatic ketone.On the other hand, aromatic polymers that have main chain structure composed of only aromatic rings and ketonic carbonyl groups are another type of aromatic polyketones (Figure 2). 6 The authors' group has been investigating the synthesis of aromatic polyketones free from main chain hetero linkages, wholly aromatic polyketones, during recent one and a half decades. Contrary to aromatic poly(ether ketone)s, wholly aromatic polyketones were seldom reported before.Prior to discussion of synthetic chemistry of wholly aromatic polyketones, the overview of aromatic polyketones including aromatic poly(ether ketone)s is briefly summarized to discriminate between aromatic poly(ether ketone)s and wholly aromatic polyketones.Aromatic polyketones are obliged to have copolymer structure composed of aromatic rings and ketonic carbonyl groups. From this point, aromatic polyketones are regarded as polyarylenes bearing inserted carbonyl groups. These polymers are classified into wholly aromatic polyketones or others according to the absence or presence of hetero linkages in the main chain. Aromatic poly(ether ketone) is the representative polymer of the latter type.As a natural consequence of the structural characterist...
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