Cascade Nucleophilic Addition−Cyclic Michael Addition of Arynes and Phenols/Anilines Bearing Ortho α,β-Unsaturated Groups: Facile Synthesis of 9-Functionalized Xanthenes/Acridines

Abstract

A facile synthesis of xanthenes and acridines based on a cascade nucleophilic addition-cyclic Michael addition process of arynes and phenols/anilines substituted with alpha,beta-unsaturated groups at the ortho positions is described. The reaction has also been successfully extended to the synthesis of 9-spiro-xanthene and acridine derivatives with potential biochemical interest.

Autoxidative Carbon–Carbon Bond Formation from Carbon–Hydrogen Bonds

“…Xanthene and acridane derivatives are pharmaceutically active compounds and are used as dyes and fluorescent materials and chiroptical molecular switches; they also occur in natural products. [7,20] Accordingly, we anticipate further elaborations of this autoxidative coupling principle and applications towards the synthesis of complex products.…”

“…In these studies an Fe III catalyst together with tert-butyl peroxide, [4] stoichiometric amounts of the quinone DDQ, [5] or equimolar amounts of a Mn III compound at high temperature were used to synthesize products like 3 e and 3 j-m. [6] Substituted xanthenes like 3 e and 3 g have recently been synthesized via arynes. [7] The present method offers an alternative with fewer steps, cheaper reagents, and less waste.…”

Heteroannulation of Arynes with α‐Amino Imides: Synthesis of 2,2‐Disubstituted Indolin‐3‐ones and Application to the Enantioselective Total Synthesis of (+)‐Hinckdentine A

“…Alternatively,w ea lso examined the reaction of 4a with gamino-a,b-unsaturated amide 12,a iming at ao ne-step synthesis of tricycle 13. [14] However,t he reaction afforded once again the N-phenylated product 14 as the major product (67 %yield), together with atrace amount of 13 (Scheme 2b).…”

Transition-Metal-Free Synthesis of Benzo-Fused Five- and Six-Membered Heterocycles Employing Arynes

“…The reaction proceeds via the insertion of aryne into the C-N bond of amide, generating the strained four-membered intermediate. SCHEME 62 Synthesis of 9-functionalized xanthenes/acridines [85,86]. The optimal condition was the use of TBAT in toluene under microwave irradiation at 120 °C , furnishes the N-arylacridones in good to excellent yields.…”