ethyl 9H-xanthene-9-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:-50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 1.5 g (5.9 mmol) of ethyl 9H-xanthene-9-carboxylate in 20 ml of THF and 1.6 ml of DMPU under an inert atmosphere is cooled to −50° C. 4 ml (6.4 mmol) of BuLi (1.6 M in hexane) are added dropwise to this medium with stirring, and the medium is then left stirring for 10 minutes at −40° C. After allowing the reaction medium to warm to 10° C., a flow of formaldehyde generated from 5.4 g (0.18 mol) of sublimed paraformaldehyde entrained by a stream of nitrogen is bubbled in. After stirring for 2 hours at room temperature, the suspension is dispersed in 50 ml of water. The reaction medium is then extracted twice with 100 ml of ether. The combined organic phases are dried over Na2SO4. After evaporation, the residual oil is chromatographed on silica. Eluent: CH2Cl2. 1.1 g of a yellow oil are obtained (yield: 68%). the medium is then left stirring for 10 minutes at −40° C to warm to 10° C. is bubbled in After stirring for 2 hours at room temperature the suspension is dispersed in 50 ml of water The reaction medium is then extracted twice with 100 ml of ether The combined organic phases are dried over Na2SO4 After evaporation the residual oil is chromatographed on silica