Hydrochloric Acid → Methyl 5-benzyl-3-(chloromethylene)-2,3,4,5-tetrahydro-1-benzoxepin-7-carboxylate

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Reaction Conditions

Reaction Steps

1.1 equivalents of n-butyllithium are added to a suspension of 40 mg (0.12 mmol) of chloromethyltriphenylphosphonium chloride in 3 ml of tetrahydrofuran cooled to 0° C. After stirring for one hour, the ylide is added at 0° C. via a hollow tube to 30 mg (0.1 mmol) of methyl 5-benzyl-3-oxo-2,3,4,5-tetrahydro-1-benzoxepin-7-carboxylate, prepared according to example 9. After stirring at ambient temperature for 30 minutes, water, 1N hydrochloric acid and dichloromethane are added. The phases are separated by settling and then the aqueous phase is extracted three times with dichloromethane. The combined organic phases are washed with brine, are then dried and are finally concentrated under vacuum. The crude reaction product is then purified by chromatography on silica gel (ethyl acetate/heptane 5/95) to provide 18 mg (53%) of methyl 5-benzyl-3-(chloromethylene)-2,3,4,5-tetrahydro-1-benzoxepin-7-carboxylate in the form of a mixture of two isomers in a Z/E ratio (60/40); exact mass (CI): calculated 343.11009; found 343.11027.

Provenance & Evidence