Gold‐Catalyzed Tandem Cyclization/Cycloaddition Reaction of Enynones: Highly Regioselective Synthesis of Oxabicyclic Compounds and Naphthyl Ketones

Abstract

A gold‐catalyzed benzannulation of enynones for synthesizing oxabicyclic compounds and naphthyl ketones with high regioselectivity has been developed. Divergent products can be obtained from the same substrates through different types of cycloaddition. In this reaction, enynones were selectively transformed through [3+2] cycloadditions to give oxabicycles 2 in the presence of [L3AuCl] (L3=[tris(para‐trifluoromethylphenyl)phosphine], 5 mol %). When [L2(CNCH3)Au]SbF6 (L2=[2‐(di‐tert‐butylphosphino)biphenyl]) was used as the catalyst, the [4+2] cycloaddition naphthyl ketone products dihydrobenzo[f]isoquinolines 3 were obtained. The value of this method is indicated by the applicability of various enynones substrates and the highly regioselective synthesis of two potentially useful polycyclic compounds.

Transition metal catalysed cascade C–C and C–O bond forming events of alkynes

“…Interestingly, after several years, they reported the same cyclization for the synthesis of similar compounds through the usage of 5 mol% of Au( i )-complex catalyst instead of iodine (Scheme 11, section 3). 33 It was really interesting to observe a different outcome, i.e. exclusive formation of quinolines 11f upon the use of different gold( i )-complexes (Scheme 11, section 2).…”

Tandem C–H oxidation/cyclization/rearrangement and its application to asymmetric syntheses of (−)-brussonol and (−)-przewalskine E

“…In recent decades, the significant biological activity and potential pharmaceutical value of molecules with this skeleton have driven chemists to devise several methods for constructing it ( Fig. 1b ) 3 4 5 6 7 8 9 10 11 12 13 14 . Nevertheless, more efficient and practical methods are needed.…”