反应详情

温度

-40 °C

A solution of ethyl 2-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylpropanoate (43 g) in tetrahydrofuran was added to lithium aluminium hydride (220 ml of a 1M solution in ether) with stirring at -40° C. After 1 hour the solution was cooled to -70° C., diluted with ether, and treated with brine via dropwise addition, initially at -70° C. and then at -30° C. After warning to room temperature the organic layer was dried (magnesium sulphate), evaporated and the residue purified by dry column chromatography on silica gel eluting with dichloromethane to give 2-(2,3-dihydro-6-methyl-4-oxo-5-phenyl-4H-1,3-oxazin-3-yl)-2-methylpropionaldehyde as a cream solid (22.5 g), NMR 1.35(s,6H), 1.95(s,3H), 5.25(s,2H), 7.22-7.38(m,5H), 9.42(s,1H).

1. temperatureAfter 1 hour the solution was cooled to -70° C.
2. customat -30° C
3. customAfter warning to room temperature
4. dry with materialwas dried (magnesium sulphate)
5. customevaporated
6. customthe residue purified
7. dry with materialby dry column chromatography on silica gel eluting with dichloromethane