Diethyl Malonate → 2H-1-Benzopyran-3-carboxylic acid, 7-(diethylamino)-2-oxo-, ethyl ester

Participants

Reaction Steps

--A solution of 4-diethylamino-2-hydroxy-benzaldehyde (29.8 g, 154 mmol) and diethyl malonate (23.8 ml, 157 mmol) in ethanol (185 ml) was treated with piperidine (1.37 ml, 13.9 mmol) and heated under reflux for 4 h. The solution was allowed to cools then concentrated under reduced pressure to approx. half-volume diluted with ether and washed with water, dilute aq. NaOH and water, dried and evaporated under reduced pressure. Trituration of the residue with EtOH (approx. 15 ml) gave yellow crystals which were recrystallised from EtOAc-light petroleum to give the ester 1 as bright yellow prisms (18 the m.p. 76-77° C. A sample recrystallised a second time had m.p. 77-78° C. (Found: C, 66.4; H, 6.7g N, 4.8. C16H9NO4 requires C, 66.4; H, 6.6; N, 4.8%). The discrepancy with the m.p. (87° C.) reported by Kendal et al. (GB 867,592), together with the sharp m.p. and satisfactory analytical result for the present sample suggests that the digits of the reported value may accidently have been transposed.

Provenance & Evidence