(3 + 3) Annulation of Nitroallylic Acetates with Stabilized Sulfur Ylides for the Synthesis of 2-Aryl Terephthalates

Abstract

A novel (3 + 3) annulation approach has been developed for the synthesis of 2-aryl terephthalates from nitroallylic acetates and stabilized sulfur ylides. The 2-aryl terephthalates, which are also biaryls bearing a terephthalate moiety, are formed through a cascade of reactions such as a γ-selective S2' reaction, γ-selective intramolecular Michael addition, and two eliminations in the presence of CsCO in CHCN at room temperature. The products are formal precursors of farnesyltransferase inhibitors and are also potential monomers in polymer chemistry.

Construction of Oxepino[3,2‐b]indoles via [4+3] Annulation of 2‐Ylideneoxindoles with Crotonate‐Derived Sulfur Ylides

“…Based on our experimental results and previous related studies, [4c,f,g,h] a possible mechanism for this [4+3] annulation reactions was also proposed (Scheme 6). Firstly, deprotonation of crotonate‐derived sulfur ylides 2 results in a carbanion allylic ylide intermediate A in the presence of a base (such as Cs 2 CO 3 ).…”

“…Carbanion allylic ylide intermediates B is formed by resonance of sulfur ylide intermediate A . Then, an intermolecular Michael addition involving α‐selective addition of carbanion allylic ylide intermediate B to 2‐ylideneoxindoles 1 via soft‐soft interaction [4h] forms zwitterionic intermediate C . Next, the intermediate C easily transforms into zwitterionic intermediate E underwent two proton transfer processes (intermolecular proton transfer process may be involved).…”

Construction of CF3‐containing Oxepino[2,3‐c]pyrazole Motif via Sulfur Ylide‐mediated Annulation or Me2S involved One‐pot Reaction

“…The crotonate‐derived sulfonium salt 2 a was treated with K 2 CO 3 to give carbanion allylic ylide intermediates A , which resonated to carbanion allylic ylide B . Then an intermolecular Michael addition of B to 1 a via soft‐soft interaction [15] afforded the zwitterionic intermediate C . The intermediate C subsequently transformed into the zwitterionic intermediate F through two proton transfer processes.…”

Recent Advances on Annulation Reactions with Allyl and Propargyl Sulfonium Salts

“…As shown in Scheme 10, Namboothiri and Satham described a [3+3] annulation/aromatization of allyl sulfonium salts with the dielectrophiles 16. 18 The proposed mechanism of this annulation involves two nucleophilic attacks of the sulfur ylide on 16 and the elimination of both the dimethyl sulfide and NO 2 moieties. In the presence of Cs 2 CO 3 , terephthalates 17, which contained two different electronwithdrawing groups and an aryl group, were delivered in 31-65% yields (see selected examples 17a and 17b).…”