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Facile synthesis of (4-nitrophenyl)thio-substituted 1- pyrrolines

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2019
Korkmaz, Esra
The importance of heterocyclic compounds is enormous in synthetic organic chemistry due to their presence in bioactive molecules. Five-membered 1-pyrrolines are one of the most important classes of them. They have recently drawn great attention from synthetic chemists since they have a prominent role for the synthesis of a great number of pharmaceutical molecules. Therefore, there is intense research on their synthesis. In this project, we concentrated on the synthesis of (4-nitrophenyl)thio-substituted 1- pyrrolines. We have synthesized a variety of (4-nitrophenyl)thio-substituted 1- pyrroline derivatives with one-pot two-steps reactions by using two different bases. Firstly, the synthesis of α,β-alkynic ketone derivatives was achieved from aryl chlorides and terminal alkynes by using Pd-catalyzed coupling reaction. Secondly, 21 diverse derivatives of N-propargylic β-enaminones were synthesized with conjugate addition of propargylamine to α,β-alkynic ketones. In the last step of this project, we investigated the addition of 4-nitrobenzenesulfenyl chloride to N-propargylic β-enaminones and the cyclization of resulting intermediate compound. After we treated N-propargylic β-enaminones with 4-nitrobenzenesulfenyl chloride, NaH or Cs2CO3 was added into reaction medium for the cyclization of intermediate product in ACN at reflux condition. Each derivative was synthesized by using both bases and their yields were compared. Consequently, one-pot two-steps reactions were performed and 21 novel derivatives of (4-nitrophenyl)thio-substituted 1-pyrrolines were obtained in good yields.