反应详情

Using the procedure of example 30, 2.7 g (10 mmoles) of the aldehyde product from example 83 was condensed with 3.7 g (10.6 mmoles) of (carbethoxymethylene)triphenylphosphorane, in 30 ml of toluene (1.5 hours at 100° C.). After chromatography of the crude product on 50 g of silica gel (eluting with toluene), there was obtained 3.0 g (88.8%) of racemic-3,4-dihydro-7-(phenylmethoxy)-2H-1-benzopyran-2-propenoic acid ethyl ester (mixture of E- and Z-isomers), as a pale-yellow oil.