Reaktion #79944

Reaktionsgleichung

methylidene triphenyl phosphorane

6-bromo-2,2,4,4-tetramethyl chroman-8-carbaldehyde

Intermediate 30

6-bromo-2,2,4,4-tetramethyl chroman-8-carbaldehyde

n-butyl lithium

→

title compound

Ausbeute 72.0%

6-Bromo-8-vinyl-2,2,4,4-tetramethyl-chroman

Ausbeute 72.0%

Lösungsmittel

—

hexanes

hexane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Waschenwashed with brine (×1)
2. 2
   Trocknendried over anhydrous sodium sulfate
3. 3
   Filtrationfiltered
4. 4
   Sonstigeevaporated in vacuo to a clear oil which

Vorschrift

A solution of methylidene triphenyl phosphorane [generated from methyl triphenylphosphonium bromide (7 g, 20 mmol) and (11.8 mL, 19 mmol) of a 1.6M solution of n-butyl lithium in hexanes] was added 6-bromo-2,2,4,4-tetramethyl chroman-8-carbaldehyde (Intermediate 30, 0.52 g, 1.75 mmol). After 1 h the reaction mixture was diluted with hexane, washed with brine (×1), dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to a clear oil which was subjected to flash column chromatography over silica gel (230-400 mesh) using 2% ethyl acetate in hexane as the eluent to afford the title compound as a clear oil (0.37 g, 72%).

Quelle