Reaction #1256725

Reaction equation

methyl 5-propyl-2-trifluoromethanesulfonyloxycyclohex-1-enecarboxylate

4-ethoxy-3-fluoro-2-(2-methoxyethoxymethoxy)benzeneboronic acid

sodium metaborate

hydrazinium hydroxide

→

3-ethoxy-4-fluoro-8-propyl-7,8,9,10-tetrahydrobenzo[c]chromen-6-one

Solvents

water

water

tetrahydrofuran

Conditions

Workup

1. 1
   Otherthe aqueous phase is separated off
2. 2
   Extractionextracted twice with MTB ether
3. 3
   WashThe combined organic phases are washed with saturated sodium chloride soln
4. 4
   Dryingand dried over sodium sulfate
5. 5
   OtherThe solvent is removed under reduced pressure
6. 6
   Filtrationthe residue is filtered through silica gel with n-heptane/MTB ether (6:4)

Procedure

18.2 g (56.6 mmol) of methyl 5-propyl-2-trifluoromethanesulfonyloxycyclohex-1-enecarboxylate, 21.5 g (74.6 mmol) of 4-ethoxy-3-fluoro-2-(2-methoxyethoxymethoxy)benzeneboronic acid, 1.5 ml of water, 33 g (120 mmol) of sodium metaborate, 1.12 g (1.6 mmol) of bis(triphenylphosphine)palladium(II) chloride and 0.1 ml (1.6 mmol) of hydrazinium hydroxide are heated under reflux overnight in 300 ml of tetrahydrofuran. After addition of water, the aqueous phase is separated off and extracted twice with MTB ether. The combined organic phases are washed with saturated sodium chloride soln. and dried over sodium sulfate. The solvent is removed under reduced pressure, and the residue is filtered through silica gel with n-heptane/MTB ether (6:4), giving 3-ethoxy-4-fluoro-8-propyl-7,8,9,10-tetrahydrobenzo[c]chromen-6-one as colourless crystals.

Source