Conformational studies of 2-(4-bromophenyl)-2-oxoethyl benzoates

Abstract

Phenacyl benzoates possess commercial importance due to their various applications in the fields of synthetic and photochemistry, such as photosensitive blocking groups owing to their ease of cleavage under mild conditions. In the present study, a series of ten new 2-(4-bromophenyl)-2-oxoethyl benzoates 2(a-j), with the general formula Br(C 6 H 4 )COCH 2 OCO(C 6 H 5Àn X n ), X ¼ Cl, NO 2 or NH 2 , and n ¼ 1 or 2, have been synthesized by reacting 4-bromophenacyl bromide with various substituted benzoic acids using potassium carbonate in DMF medium at room temperature. These reactions proceeded with ease under mild conditions producing high purity products in good yield. Each product was characterized by mass spectra, elemental analysis and melting points, its 3D structure was confirmed by single-crystal X-ray diffraction studies. The X-ray 3D structures showed the flexibility of the C(¼O)-O-C-C(¼O) connecting bridge in which 7 out of 10 compounds tend to form a torsion angle in the range of 70 to 91°, whereas the rest are slightly twisted with a torsion angles of À160, 163, 176 and 178°. Their molecular conformations are in good agreement with another 22 related structures. These synthesized compounds were screened for their abilities for DPPH radical scavenging and ferric reducing anti-oxidant power. The results indicate that these compounds displayed mild anti-oxidant ability when compared to the standard anti-oxidant BHT.

Synthesis and Crystallographic Insight into the Structural Aspects of Some Novel Adamantane-Based Ester Derivatives

“…In the aspect of molecular conformation, it is noteworthy to observe that neither periplanar conformation nor mixed (periplanar and synclinal) conformation is adopted by the currently studied compounds, unlike the variations displayed in phenacyl benzoates. All present compounds adopt synclinal conformation with C13-O1-C12-C11 torsion angles falling in the range from 69.7°-86.12°, which is comparable to those previously reported for phenacyl benzoate derivatives that adopt the same conformation (71°-91°) [20]. The structural occupancies of all present and reported compounds are listed in Table 3.…”

“…The full reaction involved the synthesis of 1-adamantyl bromomethyl ketone, 1, which is essential for subsequent synthesis of 2(a-r) in accordance with the reported procedure [20], as shown in Scheme 1. ); however, the synthesis of 1 is confirmed by 1 H-NMR when the peak corresponding to the methyl group of 1-adamantyl methyl ketone is replaced by the peak corresponding to the methylene group near δ 4.1 ppm.…”

“…Although the torsion angle between the adamantane moiety and the adjacent carbonyl group (C1-C8-C11-O2, τ1) is one of the degrees of freedom, it was irrelevant for the comparison due to its randomness and the effect of disordered orientations. By referring to the previous report [20], torsion angle τ2, which interconnects two carbonyl groups, tends to adopt two types of conformations, either synclinal or periplanar. However, all structures reported in this study adopt only one conformation in which τ2 torsion angles are all in synclinal conformation ranging from 70°-86°, which may be due to the introduction of the bulky adamantane moiety.…”

“…After the reaction completed, the reaction mixture was poured into ice-cooled water and kept stirring for 10 min. The solid obtained was filtered out, washed successively with distilled water and recrystallized from acetone after it dried [20]. All targeted compounds were synthesized in good yield and high purity.…”

Synthesis, Structural and Antioxidant Studies of Some Novel N-Ethyl Phthalimide Esters

“…The intermediate 3 was synthesized according to the procedure reported [ 13 , 14 ]. The derivatives 4(a-n) was obtained by nucleophilic substitutions by benzoic acid derivatives, as per the reported procedure [ 15 ]. The target products 4(a-n) were confirmed by analytical and spectral studies.…”