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β‐Nitroacrylates as Starting Materials of Thiophene‐2‐Carboxylates Under Continuous Flow Conditions
Author(s) -
Chiurchiù Elena,
Patehebieke Yeersen,
Gabrielli Serena,
Ballini Roberto,
Palmieri Alessandro
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201801660
Subject(s) - aromatization , chemistry , thiophene , conjugate , domino , flow chemistry , combinatorial chemistry , continuous flow , flow (mathematics) , organic chemistry , catalysis , biochemical engineering , mathematical analysis , geometry , mathematics , engineering
Abstract We report herein a general and efficient continuous flow‐based protocol for synthesizing thiophene‐2‐carboxylates starting from ketal‐functionalized β‐nitroacrylates. The protocol involves (i) a promoter‐free conjugate addition of thioacetic acid to β‐nitroacrylates, (ii) a base‐induced elimination of nitrous acid, and (iii) a final acid‐promoted domino cyclization‐aromatization process to afford the title targets. Thanks to the means of the flow chemistry and the use of solid supported systems, the three steps were combined in a whole flow chemical process, by which the products were isolated in good to excellent overall yields (38–88%).