Carbocation Lewis Acid Catalyzed Diels–Alder Reactions of Anthracene Derivatives

Abstract

The carbocation salt [PhC][BArF] has been identified as a viable Lewis acid catalyst for the Diels-Alder reactions between anthracene derivatives and unsaturated carbonyl compounds with good selectivity and high efficiency.

Regenerable Acidity of Graphene Oxide in Promoting Multicomponent Organic Synthesis

“…Ring opening of the epoxide groups relieves ring strain and forms an alpha-carbocation. The carbocation could act as a Lewis acid aiding dehydration of the beta-hydroxy intermediate i to form the Knoevenagel intermediate ii 25,26,57,58 . Nucleophilic attack of 3-amino-1,2,4-triazole to ii followed by 3xGO promoted dehydration of iii and cyclization reaction of iv leads to the formation of 4a .…”

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

“…We next tested the metal phosphate strategy in the Diels–Alder reaction of anthracene, for which a catalytic asymmetric version has not been achieved yet. Recently, we reported that the tritylium salt [Ph 3 C][BArF], in situ generated by Ph 3 CBr and NaBArF, could promote the Diels–Alder reaction with anthracenes and various unsaturated carbonyl compounds under mild conditions [13]. The use of latent carbocation catalysis with TP was examined in order to achieve enantioselective control.…”

“…Carbocation Lewis acid catalysis has grown significantly over the last two decades [1–13]. The development of asymmetric carbocation catalysts has been long pursued but remains a challenging task.…”

Acid Catalysis via Acid‐Promoted Electron Transfer

“…[70][71][72] Lewis acids including redoxinactive metal ions act as effective catalysts to accelerate Diels-Alder reactions of anthracenes with p-benzoquinone (Q) derivatives, which have been considered as weak or inert dienophiles. [73][74][75][76][77][78][79][80][81][82][83][84] In particular, Sc 3+ ion acts as an effective catalyst to accelerate Diels-Alder reactions of anthracene and its derivatives with Q derivatives [Eq. 1].…”

“…The photodriven Diels‐Alder reactions via photoinduced ET and charge‐transfer of the D–A complexes formed between dienes and dienophiles by irradiation have also been well recognized 70–72 . Lewis acids including redox‐inactive metal ions act as effective catalysts to accelerate Diels‐Alder reactions of anthracenes with p ‐benzoquinone (Q) derivatives, which have been considered as weak or inert dienophiles 73–84 . In particular, Sc 3+ ion acts as an effective catalyst to accelerate Diels‐Alder reactions of anthracene and its derivatives with Q derivatives [Eq.…”