Application of beta-(2-chloroaroyl) thioacetanilides in synthesis: an unusual and highly efficient access to thiochromeno[2,3-b]pyridine derivatives.
A series of unusual fused tricyclic thiochromeno[2,3-b]pyridines were successfully synthesized by tandem [3 + 3] annulation and SNAr of beta-(2-chloroaroyl) thioacetanilides with activated 4-arylidene-2-phenyloxazol-5(4H)-ones or aromatic aldehydes and ethyl 2-cyanoacetate under microwave irradiation, respectively. Because of the existence of the o-chloro atom of beta-(2-chloroaroyl) thioacetanilides, these reactions were very mild, convenient, and ortho-selective to form new fused tricyclic target molecules. In the domino processes, at least seven reactive distinct chemical sites were involved and up to three new covalent bonds and one tricycle with only cis configuration were generated. A synthetic study and mechanistic proposal for these transformations are presented.
Wen
Li-Rong
LR
Key Laboratory of Eco-Chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Sun
Ji-Hui
JH
Li
Ming
M
Sun
En-Tao
ET
Zhang
Shu-Sheng
SS
D000083:Acetanilides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011725:Pyridines / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013055:Spectrophotometry, Infrared
D000083:Acetanilides; D011725:Pyridines; C039632:thioacetanilide