Radical-carbanion cyclo-coupling in armed aromatics: overriding steric hindrance to ring closure

Abstract

Omega-(2-Halophenyl)alkyl-2-oxazolines were prepared and reacted via base promoted intramolecular coupling of radical with carbanionic centres to yield 1-phenyl-1-oxazolino-indan and -tetralin derivatives containing quaternary C-atoms.

One‐Pot Synthesis of 3‐Substituted Isoquinolin‐1‐(2H)‐ones and Fused Isoquinolin‐1‐(2H)‐ones by SRN1 Reactions in DMSO

“…Compound 13b exhibits spectral and analytical data in accordance with that in ref. [29] 5, 11,12,13-Tetrahydro-5-aza-benzo[3,4]cyclohepta[1,2-a] (19). Compound 15b exhibits spectral and analytical data in accordance with that in ref.…”

“…[16,17] Recently, this method has been applied to the synthesis of a new family of 2H-1,2-benzothiazine 1,1-dioxides [18] and 1-phenyl-1-oxazolino-indane derivatives containing quaternary carbon atoms. [19] In this field, an important example is the synthesis of 2-substituted and fused indoles by the reaction of 2-iodoaniline with ketone enolates. [20] Substituted isoquinolin-1-(2H)-ones have been obtained by reaction of o-iodo-or o-bromobenzamides with enolates of ketones in liquid ammonia under photostimulation.…”

Formation of a Tetracyclic Isoquinoline Derivative by Rearrangement of a [(Bromophenyl)butyryl]oxazolidinone

“…The presence and siting of the two carbonyl groups facilitate further rearrangement, which results in the one-pot assembly of an unusual isoquinolinone derivative with an alkyl bridge between the benzo and heterocyclic rings. The initial steps were most likely similar to those reported for the analogous oxazoline [5] and led to the radical anion 3, which closed by S RN 1-type cyclo-coupling to produce 4. An analogous process via initial aryne formation could not be ruled out.…”

“…[4] We previously reported that precursors containing bromoaryl groups attached to oxazolines by propyl and butyl linkers yielded indane and tetralin derivatives, respectively, when treated with LDA. [5] We decided to investigate analogous precursors containing oxazolidinones in the hope that more efficient and selective methodology could be developed. Accordingly, we carried out exploratory experiments with [(bromophenyl)butyryl]oxazolidinone derivatives 1, but found that, in practice, LDA-promoted reactions of 1 led to the assembly of a new fused tetracyclic cyclopentaoxazoloisoquinoline system in a remarkable multistage rearrangement.…”

Aromatic and Heteroaromatic Substitution by S RN 1 and S N 1 Reactions

“…is modest [55]. However, the maximum selectivity achieved with a 4-isopropyl substituent in the oxazoline (48% d.r.)…”