ABSTRACT
An efficient gold-catalyzed synthetic protocol for the construction of 1,2-dihydro[c][2,7]naphthyridines from 2-aminophenyl prop-2-yn-1-yl enaminones has been developed. In this organic transformation new C-C and C-N bond formations occur via 6-endo-dig cyclization and condensation. 1,2-Dihydro[c][2,7]naphthyridine derivatives were obtained in good to excellent yields in a one-pot synthesis at ambient temperature.
ABSTRACT
An efficient gold-catalyzed synthesis of substituted 3-methylene-3,4-dihydrobenzo[b]oxepinones from ortho-O-propargyl substituted aryl enaminones has been achieved. In this transformation a new C-C bond formation occurred regioselectively via 7-exo-dig cyclization. Benzooxepinone derivatives were obtained in good to excellent yields in a one-pot synthesis at ambient temperature.
ABSTRACT
An efficient and mild one-pot, gold-catalyzed intramolecular cyclization of N-propargylic ß-enaminones has been achieved for the generation of 1,4-oxazepine derivatives. This synthetic transformation tolerates a range of substituted N-propargylic ß-enaminones in moderate to good yields.
ABSTRACT
A gold(I) catalysed reaction between N-propargylic ß-enaminones and arynes was developed to access 3-methylene-1-pyrrolines. The title compounds were obtained in 57-78% yields. This reaction is useful for the generation of substituted 1-pyrrolines exhibiting significant molecular complexity.
ABSTRACT
Two chiral Schiff-base complexes of copper(II) have been successfully encapsulated inside the cavity of zeolite-NaY via a "ship in a bottle" synthesis method. The presence of the two complexes inside the cages of zeolite-Y has been confirmed based on various spectrochemical and physicochemical techniques, viz. FTIR, UV-vis/DRS, ESR, XPS, CV, EDX, SEM, and TGA. Zeolite-encapsulated chiral copper(II) Schiff-base complexes are found to give a high-enantioselective (84% ee, R conformation) nitro-aldol product at -20 °C. The encapsulated copper complexes are found to show higher catalytic efficiency than their homogeneous counterparts under identical conditions. Density functional theory (DFT) calculation has been implemented to understand the effect of the zeolite matrix on structural, electronic, and reactivity properties of the synthesized complexes. Theoretical calculation predicts that upon encapsulation into the zeolite matrix the Cu center becomes more susceptible to nucleophilic attack, favoring a nitro-aldol reaction. A plausible mechanism is suggested based on the experimental and theoretical results. The structures of reaction intermediates and transition state(s) involved in the catalytic cycle are derived using DFT.
