CuBr-mediated synthesis of 1,4-naphthoquinones via ring expansion of 2-aryl-1,3-indandiones

Abstract

A CuBr-mediated direct insertion of alkenes into an unstrained ring 2-aryl-1,3-indandiones is reported, which provides a one-carbon ring expansion strategy for the synthesis of 1,4-naphthoquinones. Entirely differing from the existing...

Synthesis of the Tetracyclic Spiro-naphthoquinone Chartspiroton

“…18 More recently, Zhang and co-workers extended this chemistry to the construction of 1,4-naphthoquinones via a copper(I)-mediated insertion of alkenes into 2-aryl-1,3-indandiones. 19 The implementation of this ring expansion strategy to the retrosynthesis of chartspiroton (1) led to removal of the spiro-lactone and revealed biaryl 5a as our first key intermediate (Figure 1B). Ring contraction of the naphthalene component produced the 2,2-disubstituted 1,3-indandione 6, which was further traced back to 7.…”

“…As a result, we evaluated alternative ring expansion strategies for their potential to produce the desired molecular architecture. This guided us to 2-arylated 1,3-indandiones as valuable precursors to tetra- ortho -substituted biaryl subunits. , In seminal work by Radulescu and Gheorgiu, it was shown that indanones undergo acid- and base-mediated ring expansion to tetrasubstituted naphthalenes . More recently, Zhang and co-workers extended this chemistry to the construction of 1,4-naphthoquinones via a copper­(I)-mediated insertion of alkenes into 2-aryl-1,3-indandiones .…”

“…This guided us to 2-arylated 1,3-indandiones as valuable precursors to tetra- ortho -substituted biaryl subunits. , In seminal work by Radulescu and Gheorgiu, it was shown that indanones undergo acid- and base-mediated ring expansion to tetrasubstituted naphthalenes . More recently, Zhang and co-workers extended this chemistry to the construction of 1,4-naphthoquinones via a copper­(I)-mediated insertion of alkenes into 2-aryl-1,3-indandiones . The implementation of this ring expansion strategy to the retrosynthesis of chartspiroton ( 1 ) led to removal of the spiro-lactone and revealed biaryl 5a as our first key intermediate (Figure B).…”