Nazarov Reagent: New Role for the [4+2] Domino Benzannulation Reaction to Construct Polysubstituted Benzenes

Abstract

Dedicatedtothe 100th anniversary of Nankai University and dedicated to the 100th anniversary of the birth of Academician Ruyu Chen Abstract: An ew role for the Nazarovr eagent was revealed in the [4+ +2] benzannulation reaction, and delivered as eries of polyfunctional benzenes in high yields under mild conditions. This metal-free process not only expanded the applicationo ft he Nazarov reagent in organic synthesis, but also provided an ew,e fficient way to construct polyfunctional benzenes.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Benzannulation Reactions: A Case for Perspective Change From Arene Decoration to Arene Construction

“…The reaction of Nazarov reagent 91 with 1,3-bis (sulfonyl)butadiene 92 in presence of equimolar amounts of DABCO proceeded smoothly to afford polysubstituted benzene derivatives 93 in good yields (Scheme 28). [38] N-Heterocyclic carbene (NHC)-catalysed [4 + 2] benzannulation have also been developed for the construction of substituted arenes. For example, Wang and co-workers reported a NHC-catalysed oxidative annulation reaction of αcyanoenones 94 and enals 95.…”

Recent Advances in Organocatalyst‐Mediated Benzannulation Reactions

“…This metal-free annulation reaction was conducted under mild conditions using air-or moisture-stable reagents with high atom economy, which made the Nazarov reagent a new and useful reagent for benzannulation reactions (Scheme 18). [45] More recently, the Han and Peng's group reported a highly chemo-and regioselective substrate-directed benzannulation of trisubstituted CF 3 -alkenes 88 and 2benzylidenemalononitriles 87 or 2-nitroallylic acetates 90, affording a broad spectrum of tri-fluoromethylarene derivatives in generally high yields. [46] When 2-benzylidenemalononitriles 87 were used as electrophiles, the Michael-initiated (4 + 2) benzannulation adducts 89 were selectively obtained; while 2-nitroallylic acetates 90 were applied as dielectrophilic synthons, an efficient Rauhut-Currier-initiated (3 + 3) benzannulation reaction was observed.…”

Multicomponent and Metal‐Free Diels–Alder/Aromatization Approach to the Stereospecific Synthesis of E‐(Hetero)Stilbenes and Diarylacetylenes

“…At last, a poorly explored approach is the de novo synthesis of one of the two aromatic rings of the stilbene scaffold by annulation reactions (Path E). To the best of our knowledge, only two examples of this strategy are present in the literature [34,35] …”