title: Neighboring group participation of the indole nucleus: An unusual DAST-mediated rearrangement reaction
abstract: A rearrangement reaction involving the indole nucleus was investigated using stereochemical markers and low-temperature NMR experiments. Treatment of (3S, 4S)-3-hydroxy-4-(2-phenyl-1H-indol-3-yl)-piperidine-1-carboxylic acid benzyl ester (>90% ee) with diethylaminosulfur trifluoride gave stereospecifically (3S, 4S)-4-fluoro-3-(2-phenyl-1H-indol-3-yl)-piperidine-1-carboxylic acid benzyl ester (>90% ee) with complete regioselectivity. The initial formation of a reactive spirocyclopropyl-3H-indole intermediate is believed to be responsible for the stereo- and regiochemical outcome of the reaction.
authors.affiliation: Merck & Co., Inc., 126 East Lincoln Avenue, Rahway, New Jersey 07065, USA.
authors.initials: DJ
authors.lastname: Hallett
authors.initials: U
authors.lastname: Gerhard
authors.initials: SC
authors.lastname: Goodacre
authors.initials: L
authors.lastname: Hitzel
authors.initials: TJ
authors.lastname: Sparey
authors.initials: S
authors.lastname: Thomas
authors.initials: M
authors.lastname: Rowley
authors.initials: RG
authors.lastname: Ball