反应详情

To a solution of 42.0 g of (RS)-3,4-dihydroxy-6-methoxy-7-methyl-1,3-dihydro-isobenzofuran-1-one in 1 l of N,N-dimethylformamide were added 23.0 g of 1,1,3,3-tetramethylguanidine. The solution was stirred for 30 min and then, 48.4 g of allyl bromide were added and stirring was continued for 3 h. The mixture was evaporated in vacuo and the residue was dissolved in 0.7 l of ethyl acetate. The solution was washed with brine, dried over sodium sulfate, and the solvent was evaporated in vacuo. The solid residue was crystallized from tert-butyl methyl ether to give 37.3 g of 2-formyl-3-hydroxy-5-methoxy-6-methylbenzoic acid allyl ester as white crystals of m.p. 73°-74° C.

1. stirringstirring
2. waitwas continued for 3 h
3. customThe mixture was evaporated in vacuo
4. dissolutionthe residue was dissolved in 0.7 l of ethyl acetate
5. washThe solution was washed with brine
6. dry with materialdried over sodium sulfate
7. customthe solvent was evaporated in vacuo
8. customThe solid residue was crystallized from tert-butyl methyl ether