Reaktion #52389

Reaktionsgleichung

Intermediate 40

6-bromo-8-carbonyl-3,4-dihydro-4,4-dimethylspiro[2H-1-benzopyran-2,1′-cyclopropane]

methylidene triphenyl phosphorane

ethyl acetate

6-bromo-8-carbonyl-3,4-dihydro-4,4-dimethylspiro[2H-1-benzopyran-2,1′-cyclopropane]

→

title compound

6-Bromo-3,4-dihydro-4,4-dimethyl-8-vinylspiro[2H-1-benzopyran-2,1′-cyclopropane]

Lösungsmittel

hexane

Reaktionsbedingungen

Vorschrift

Following general procedure N and using A solution of methylidene triphenyl phosphorane [generated from methyl triphenylphosphonium bromide (7 g, 20 mmol) and 1.6M solution of n-butyl lithium in hexanes (11.8 mL, 19 mmol)], 6-bromo-8-carbonyl-3,4-dihydro-4,4-dimethylspiro[2H-1-benzopyran-2,1′-cyclopropane](Intermediate 40, 2.06 g, 7 mmol) followed by flash column chromatography over silica gel (230-400 mesh) using 1-2% ethyl acetate in hexane as the eluent, the title compound was obtained as a clear oil (1.36 g, 66%).

Quelle