Multi-Step Polymer-Assisted Solution-Phase (PASP) Library Synthesis of Functionalized Diaminobenzamides

Unexpected Diels–Alder/Carbonyl-ene Cascade toward the Biomimetic Synthesis of Chloropupukeananin

“…The preparation of MOB precursor 15 was commenced with the removal of the Me group of chlorophenol 19 (Scheme ). Selective protection of the resulting catechol gave phenol 20 , which was subjected to S N Ar reaction with benzyl 2-fluoro-5-nitrobenzoate to give diaryl ether 21 in high yield. Diaryl ether 21 was transformed to 22 by a conventional three step sequence of reactions.…”

Catalyst-Free Microwave-Assisted Amination of 2-Chloro-5-nitrobenzoic Acid

“…Previous reports on the synthesis of N-substituted 5-nitroanthranilic acid derivatives employed (a) micellar catalysis (cetyltrimethylammonium bromide) in water for the preparation of 3a from 2-fluoro-5-nitrobenzoic acid and aniline, or (b) strong base (LiHMDS) for the reaction of 2-fluoro-5-nitrobenzoic acid with p -fluoroaniline yielding 3b , or (c) bronze as a catalyst in the presence of bases for the reaction of 2-chloro-5-nitrobenzoic acid with anilines in 1-pentanol yielding 3f and 3g 14 (for structures of compounds see Table ). Furthermore, the synthesis of 2-benzylamino-5-nitrobenzoic acid ( 3t ) has been described by a three-step procedure starting from 2-fluoro-5-nitrobenzoic acid involving acid protection . All of the described reactions did not appear to be generally applicable and suffered from further drawbacks, such as reaction at −78 °C and application of strong base, long reaction times, ,, need for chromatographic purification, need for protecting the carboxylic acid function, or moderate yields …”

“…Furthermore, the synthesis of 2-benzylamino-5-nitrobenzoic acid ( 3t ) has been described by a three-step procedure starting from 2-fluoro-5-nitrobenzoic acid involving acid protection . All of the described reactions did not appear to be generally applicable and suffered from further drawbacks, such as reaction at −78 °C and application of strong base, long reaction times, ,, need for chromatographic purification, need for protecting the carboxylic acid function, or moderate yields …”