Bispidine Platform as a Tool for Studying Amide Configuration Stability

In this work, the solution conformations of seventeen 3,7-diacyl bispidines were studied by means of NMR spectroscopy including VT NMR experiments. The acyl groups included alkyl, alkenyl, aryl, hetaryl, and ferrocene moieties. The presence of syn/anti-isomers and their ratios were estimated, and some reasons explaining experimental facts were formulated. In particular, all aliphatic and heterocyclic units in the acylic R(CO) fragments led to an increased content of the syn-form in DMSO-d6 solutions. In contrast, only the anti-form was detected in DMSO-d6 and CDCl3 in the case when R = Ph, ferrocenyl, (R)-myrtenyl. In the case of a chiral compound derived from the natural terpene myrtene, a new dynamic process was found in addition to the expected inversion around the amide N-C(O) bond. Here, rotation around the CO-C=C bond in the acylic R fragment was detected, and its energy was estimated. For this compound, ΔG for amide N-C(O) inversion was found to be equal to 15.0 ± 0.2 kcal/mol, and for the rotation around the N(CO)–C2′ bond, it was equal to 15.6 ± 0.3 kcal/mol. NMR analysis of the chiral bispidine-based bis-amide was conducted for the first time. Two X-ray structures are reported. For the first time, the unique syn-form was found in the crystal of an acyclic bispidine-based bis-amide. Quantum chemical calculations revealed the unexpected mechanism for amide bond inversion. It was found that the reaction does not proceed as direct N-C(O) bond inversion in the double-chair (CC) conformation but rather requires the conformational transformation into the chair–boat (CB) form first. The amide bond inversion in the latter requires less energy than in the CC form.

A simple setup miniaturization with multiple benefits for Green Chemistry in nanoparticle synthesis

The development of nanomaterials often relies on wet-chemical syntheses performed in reflux-setups using round-bottom-flasks. An alternative approach to synthesize nanomaterials is here presented that uses glass tubes designed for NMR analysis as reactors. This approach uses less solvent, uses less energy, generates less waste, provides safer conditions, is less prone to contamination and is compatible with high throughput screening. The benefits of this approach are illustrated by an in breadth study with the synthesis of gold, iridium, osmium and copper sulfide nanoparticles.

NMR analysis of pine tree oleoresin composition of the Pinus subgenus

Методом ЯМР проведен анализ состава живиц восьми видов сосен подрода Pinus: черной австрийской (P. nigra), аллепской (P. halepensis), горной (P. montana), жесткой (P. rigida), Коха (P. kochiana Klotsch), Муррея (P. murrayana Balf), обыкновенной (P. sylvestris) и Палласа (P. nigra subsp. pallasiana), произрастающих в различных районах. Кроме того, исследовано содержание смоляных кислот, выделенных в 1963 г. из живиц трех видов сосен того же подрода: черной австрийской, крючковатой (P. uncinata) и кулундинской (P. sylvestris ssp. Kulundensis). Установлено, что состав живиц названных видов сосен хорошо описывается наличием восьми смоляных кислот (абиетиновая, дегидроабиетиновая, изопимаровая, левопимаровая, неоабиетиновая, палюстровая, пимаровая и сандаракопимаровая) и девяти монотерпенов (камфен, 3-карен, лимонен, мирцен, α-пинен, β-пинен, терпинолен, βфелландреен, п-цимол). Количественное содержание этих смоляных кислот зависит от многих факторов (вида сосен, времени и места сбора живицы, а также условий сбора и хранения образцов). Кроме того, наблюдаются реакции изомеризации и окисления, приводящие к перераспределению состава. В изученных живицах содержание монотерпенов сильно отличается, являясь наименьшим у сосны аллепской и наибольшим у сосны обыкновенной. The NMR method was used to analyze oleoresin composition of eight species of Pinus subgenus: Austrian black (P. nigra), Alleps (P. halepensis), mountain (P. montana), hard (P. rigida), Koch (P. kochiana Klotsch), Murray (P. murrayana Balf), common (P. sylvestris) and Pallas (P. nigra subsp. pallasiana) growing in different areas. In addition, the content of resin acids isolated in 1963 from the oleoresins of three species of pines belonging to the same subgenus: black Austrian, hooked (P. uncinata) and Kulunda (P. sylvestris ssp. Kulundensis) was studied. It was found that the oleoresin composition of the named pine species is well described by the presence of eight resin acids (abietic, dehydroabietic, isopimaric, levopimaric, neoabietic, palustrine, pimaric and sandaracopymaric) and nine monoterpenes (camphor, 3-caren, limonene, myrcene, α-pinene, β-pinene, terpinolen, β-felandreene, p-cymol). The quantitative content of these resin acids depends on many factors (pine species, time and place of oleoresin collection, and sample collection and storage conditions). In addition, isomerization and oxidation reactions are observed, leading to a redistribution of the composition. In the studied oleoresins, the content of monoterpenes differs greatly, being the lowest in Alleps pine and the highest in Scots pine.

Synthesis, Characterization and Antimicrobial studies of N-tert-amyl acrylamide (NTA) and 7-methacryloyloxy-4- methylcoumarin (MACU) Copolymers

Copolymers of N-tert-amylacrylamide (NTA) and 7-methacryloyloxy-4-methylcoumarin (MACU) were prepared by free radical polymerization in DMF at 600C using AIBN as an initiator. The copolymer compositions were determined by 1H-NMR analysis. The reactivity ratios of monomers were determined by Fineman-Ross (FR) (r1 = 1.33 and r2 = 0.60), KelenTudos (KT) (r1 = 1.33and r2 = 0.59). The r1.r2 = 0.798 indicated the formation of random copolymers.Tg found to increasing feed content of MACU. The antimicrobial studies showed that the copolymers are active against both Bacteria and Fungi.