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Abstract: 3,4-Dihydroquinolin-2-ones are of great importance in the areas of pharmaceuticals. However, the direct intramolecular radical cyclizations of the corresponding amide compounds favor 5-exo products 2. Reports on the radical cyclization reactions producing 3,4-dihydroquinolin-2-one derivatives are limited. Herein, an efficient tandem reaction combining radical and ionic processes was developed, which provides a practical synthetic strategy for the synthesis of substituted 3,4-dihydroquinolin-2-ones from simple and readily available precursors under neutral reaction conditions. [Copyright &y& Elsevier]

A molecular dynamics simulation of the folding of a short alanine-based helical peptide of 17 residues with three Glu...Lys (i, i4) salt bridge pairs, referred to as the AEK17 peptide, was carried out. The simulation gave an estimated simulation folding time of 2.5 ns, shorter than 12 ns for an alanine-based peptide of 16 residues with three Lys residues only, referred to as the AK16 peptide, simulated previously. After folded, the AEK17 peptide had a helical content of 77%, in excellent agreement with the experimentally determined value of 80%. An examination of the folding pathways of AEK17 indicated that the peptide proceeded via three-turn helix conformations more than the helix-turn-helix conformation in the folding pathways. An analysis of interactions indicated that the formation of hydrogen bonds between Lys residue side chains and backbone carbonyls is a major factor in the abundant conformation of the three-turn helix intermediate. The substitution of three Ala with Glu residues reduces the extent of hydrophobic interaction in alanine-based AK peptides with the result that the breaking of the interactions of Lys -NH3(side chain)...CO(backbone) is a major activation action for the AEK17 to achieve a complete fold, in contrast to the AK16 peptide, in which breaking non-native hydrophobic interaction is the rate-determining step. [ABSTRACT FROM AUTHOR]

Fourteen of phosphonates containing quinoline were synthesized and the preliminary bioassay indicated that these compounds exhibited a little better fungicidal and lower herbicidal activities than the starting compound Quinclorac. [ABSTRACT FROM AUTHOR]

A variety of benzofuranone‐based spiroisochromenes were originally designed and synthesized to gain insight into the oxa‐6π electrocyclic reaction of cis,cis‐1,8‐dioxatetraene for the first time. The stability of the 1,8‐dioxatetraene intermediate is governed by its steric congestion and can be fine‐tuned through modification of the backbone structure, leading to the reactivity differences in the 6π electrocyclic reaction and the emergence of photochromic properties. Upon exposure to light, benzofuranone‐based spiroisochromenes undergo isomerization to give 1,8‐dioxatetraene intermediates. The stability of the intermediate is governed by its steric congestion and can be fine‐tuned through modification of the backbone structure, leading to the emergence of photochromic properties. [ABSTRACT FROM AUTHOR]

A variety of benzofuranone‐based spiroisochromenes were originally designed and synthesized to gain insight into the oxa‐6π electrocyclic reaction of cis,cis‐1,8‐dioxatetraene for the first time. The stability of the 1,8‐dioxatetraene intermediate is governed by its steric congestion and can be fine‐tuned through modification of the backbone structure, leading to the reactivity differences in the 6π electrocyclic reaction and the emergence of photochromic properties. [ABSTRACT FROM AUTHOR]

Nitrosation reactions of malononitrile by three nitrosating agents, HONO, ClNO, and NO, have been theoretically investigated at the B3LYP/cc-pVTZ and MP2/cc-pVDZ levels. Two possible competitive paths for nitrosation of malononitrile to give 2-nitroso-malononitrile were proposed: (a) direct C-nitrosation and (b) N-nitrosation and subsequent nitroso transfer from N to C atom. The calculations show that at both B3LYP and MP2 levels, path b is kinetically favored over path a for nitrosations by HONO and NO. In the case of ClNO, the B3LYP predicts preference of path b, while the MP2 calculations suggest that both paths have similar rate-determining barriers. The data suggest that NO is the preferred nitrosating agent for the nitrosation of malononitrile in aqueous solution. Transformation of 2-nitroso-malononitrile to form malononitrileoxime via intramolecular proton transfer has also been explored, and it is found that inclusion of an assistant water molecule can drastically accelerate the tautomerization. [ABSTRACT FROM AUTHOR]

The thermal behavior and decomposition reaction kinetics of 2-nitroimino-5-nitro-hexahydro-1,3,5-triazine (NNHT) were investigated by TG–DTG and DSC under atmospheric pressure and flowing nitrogen gas conditions. The results show that the thermal decomposition process of NNHT has two mass loss stages. The exothermic decomposition reaction mechanism obeys chemical reaction rule. The kinetic parameters of the reaction are E a =131.77kJmol−1, lg(A/s−1)=12.56, respectively. The kinetic equation can be expressed as: . The critical temperature of thermal explosion of NNHT obtained from the peak temperature (T p) is T bp =467.22K. The entropy of activation (ΔS ≠), enthalpy of activation (ΔH ≠), and free energy of activation (ΔG ≠) of the reaction are −7.978Jmol−1 K−1, 127.99kJmol−1 and 131.62kJmol−1, respectively. [Copyright &y& Elsevier]

1,2-Diarylethanones suffer -CO-CH2- bond scission under aerobic conditions in the presence of CuCl2 as catalyst enabling the formation of amides with a broad variety of aryl-, hetaryl-, and (di)alkylamines in modest to high yields. [ABSTRACT FROM AUTHOR]

A new complex catalytic system for the cleavage of carbon-carbon triple bond is firstly developed. [ABSTRACT FROM AUTHOR]