Synthesis of α-indanones via intramolecular direct arylation with cyclopropanol-derived homoenolates

Abstract

A palladium-catalysed, tandem cyclopropanol rearrangement and direct arylation approach for the synthesis of 1-indanones is reported. The reaction is generally high yielding, uses oxygen as the terminal oxidant and tolerates a range of functional groups on the aryl ring.

Recent Advances in the Synthesis of Indanes and Indenes

“…Suitably substituted cyclopropane derivatives are excellent substrates for the synthesis of indanes . In a recent example, 2,2‐dialkyl‐1‐phenylcyclopropanols 155 were converted into 1‐indanones 156 when treated with catalytic amounts of Pd(OAc) 2 , KOAc and TBAF under oxygen atmosphere (Scheme ) .…”

“…In a recent example, 2,2‐dialkyl‐1‐phenylcyclopropanols 155 were converted into 1‐indanones 156 when treated with catalytic amounts of Pd(OAc) 2 , KOAc and TBAF under oxygen atmosphere (Scheme ) . The proposed mechanism involves the ring opening, promoted by O‐palladation, followed by intramolecular ortho ‐metalation, reductive elimination, and palladium reoxidation (Scheme ) . In another process, trans ‐2‐aroyl‐3‐arylcyclopropane‐1,1‐dicarboxylates afforded functionalized 1‐indanone derivatives upon treatment with TiCl 4 , through a ring‐opening Nazarov‐type cyclization sequence …”

“…The proposed mechanism involves the ring opening, promoted by O‐palladation, followed by intramolecular ortho ‐metalation, reductive elimination, and palladium reoxidation (Scheme ) . In another process, trans ‐2‐aroyl‐3‐arylcyclopropane‐1,1‐dicarboxylates afforded functionalized 1‐indanone derivatives upon treatment with TiCl 4 , through a ring‐opening Nazarov‐type cyclization sequence …”

“… Synthesis of 1‐indanones 156 by Pd II ‐catalyzed ring expansion of 2,2‐dialkyl‐1‐phenylcyclopropanols 155 …”

“…[72] Chem.E ur.J.2016, 22,5056 -5094 www.chemeurj.org Suitably substituted cyclopropane derivatives are excellent substrates for the synthesis of indanes. [73] In ar ecent example, 2,2-dialkyl-1-phenylcyclopropanols 155 were converted into 1indanones 156 when treated with catalytic amounts of Pd(OAc) 2 ,K OAc and TBAF under oxygen atmosphere (Scheme 63). [73a] The proposed mechanismi nvolves the ring opening, promoted by O-palladation, followed by intramolecular ortho-metalation,r eductivee limination, and palladium reoxidation (Scheme 63).…”