China
Africa
Explore chapters and articles related to this topic
Nonconjugated Unsymmetrical Dienes
Published in George B. Butler, Cyclopolymerization and Cyclocopolymerization, 2020
In a continuing study of radical cyclization, cyclization of diversely substituted δ,ϵ-unsaturated free radicals was studied. Structures, where R and R′ are H or CH3 were studied.48 When X = CO2C2H5 and y = CO2C2H5 or x = Cl and y = CO2C2H5 or x = CH3CO and y = H, the five-membered ring was the main product. When x = CN and y = CO2C2H5, the two ring products were obtained in equal amounts. When x = CN and y = CO2C2H5, the six-membered ring was the main product (3-9).
Microwave Synthetic Technology
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Biswa Mohan Sahoo, Bimal Krishna Banik, Jnyanaranjan Pa
Manganese (III)-promoted radical cyclization of arylthioformanilides and α-benzoyl thioformanilides is a microwave-assisted example for the synthesis of 2-arylbenzothiazoles and 2-benzoylbenzothiazoles. In this study, manganese triacetate is introduced as a new reagent to replace potassium ferricyanide or bromide. The 2-substituted benzothiazoles are generated in 6 minutes at 1100˚C under microwave irradiation (300W) in a domestic oven with no real control of the temperature (reflux of acetic acid). Conventional heating (oil bath) of the reaction at 1100˚C for 6 hours gave similar yields [76].
Five-Membered Fused Polyheterocycles
Published in Navjeet Kaur, Metals and Non-Metals, 2020
4-Pyridone undergoes radical cyclization to afford isoindolinone with the loss of a chlorine atom [177]. The isoquinolin-1-ones can also be subjected to intramolecular free radical arylations [178]. Several intramolecular radical additions to quinolines and pyridines at the 2-, 3-, and 4-positions have been shown to be facile reactions [179–185]. Occasionally, rearrangements have also been reported (Scheme 73).
Metal- and nonmetal-catalyzed synthesis of five-membered S,N-heterocycles
Published in Journal of Sulfur Chemistry, 2018
Navjeet Kaur, Nirmala Kumari Jangid, Vivek Sharma
The radical cyclization of α-benzoyl thioformanilides and arylthioformanilides was promoted by manganese(III) for the synthesis of 2-benzoylbenzothiazoles and 2-arylbenzothiazoles under microwaves [139] (Scheme 41). In this study, potassium ferricyanide or bromide was replaced by manganese triacetate as a new reagent. The 2-substituted benzothiazoles were produced under MW (300 W) in a domestic oven at 110°C for 6 min with no real control of the temperature (reflux of acetic acid). Similar yields were observed under conventional heating (oil bath) for 6 h at 110°C.
Synthesis of six- and seven-membered and larger heterocylces using Au and Ag catalysts
Published in Inorganic and Nano-Metal Chemistry, 2018
In starting compound, a vinyl halide closed the bridged piperidine ring by Heck cyclization in the last step during the total synthesis of apparicine. Allylamine derivative was produced from intermediate and subsequently ketone-alkene functional groups were interconverted. The allylamine derivative underwent an acyl radical cyclization to generate azocinoindole intermediate (Scheme 37).[86a,b]