Facile Synthesis of 3-Nitro-2-substituted Thiophenes
摘要:
A new approach to 3-nitro-2-substituted thiophenes has been developed. Exposure of commercially available 1,4-dithane-2,5-diol to nitroalkenes in the presence of 20% triethylamine results in a tandem Michael intramolecular Henry reaction to form the corresponding tetrahydrothiophene. Subsequent microwave irradiation on acidic alumina in the presence of chloranil effects the solvent free dehydration and aromatization to form 3-nitro-2-substituted thiophenes cleanly and rapidly. A simple workup procedure removes the requirement for purification by chromatography in most cases.
A one-pot procedure was developed to prepare new 2-aryl-5-nitrothiophenes efficiently from bromonitromethane and 3-chloro-3-aryl-propenals. Nitrothiophenes were synthesized in good yields with a simple and easy workup procedure.
A one-pot synthesis of 3-nitrothiophene and 3-nitro-2-substituted thiophenes
作者:Neasa McNabola、Cornelius J. O'Connor、Mark D. Roydhouse、Michael D. Wall、J. Mike Southern
DOI:10.1016/j.tet.2015.05.032
日期:2015.7
A one-pot approach to the synthesis of 3-nitrothiophene and 3-nitro-2-substituted thiophenes has been developed. Exposure of 1,4-dithane-2,5-diol to nitroacetates or nitroalkenes in the presence of 25% triethylamine and subsequent treatment with molecular sieves and combinations of silica gel or acidic alumina with DDQ or chloranil formed 3-nitrothiophene or a number of 3-nitro-2-substituted thiophenes