A solvent-free catalytic protocol for the Achmatowicz rearrangement

Abstract

A solvent-free catalytic protocol for the Achmatowicz rearrangement was developed and enabled one-pot sequential reactions.

A Green Catalyst Fe(OTs)3/SiO2 for theSynthesis of 4‐Pyrrolo‐12‐oxoquinazolines

“…[9,10] The utilization of solvent-free protocols remains as a straight forward process by simplifying the product recovery, avoiding the use of toxic solvents, lessening waste generation and reducing the operational costs without altering the physical properties of the starting materials and nature of the reactions. [11,12,13] Solvent free reactions using mechanical grinding have been reported for Grignard reaction, [14] Reformatsky reaction, [15] Aldol condensation, [16] Claisen condensation [17] etc. In these solvent free reactions, it is known that reactivity is usually enhanced as a result of the intimacy of the reagents.…”

Mechanochemical Rearrangements

“…Additionally, solvent-free protocols employing a solid support ( i.e ., acidic α-Al 2 O 3 ) performed in both a planetary ball-mill (Scheme ) and a conventional round-bottomed flask using a magnetic stirrer were also developed. Both protocols led to comparable yields and kinetics affording the same reaction products, equal to solution-based procedures, which questions the need for a mechanochemical activation process.…”

Collective Asymmetric Total Syntheses of Marine Decahydroquinoline Alkaloid Lepadins A–E, H, and ent-I

“…Herein we report a new efficient strategy that allows the asymmetric synthesis of the DHQ core in only five steps (from known furfuryl amide 1 ) on a gram scale (Scheme b). This strategy features our green oxone-halide oxidation for both the aza-Achmatowicz rearrangement − and the in situ generation of nitrile oxide for the intramolecular [3 + 2]-cycloaddition. The collective total syntheses of lepadins A–E, H, and ent -I were achieved within 10 steps from DHQ ( 3 ), which represents the most flexible and efficient synthesis of lepadins.…”