反应详情

According to the procedure reported by Wynberg (J. Org. Chem. 1993, 58, 5101), a solution 0.50 g (2.9 mmol) of racemic (7RS,9aSR)-7-hydroxymethyl-2,3,4,6,7,8,9,9a-octahydro-1H-pyrido[1,2-a]pyrazine in 10 mL of dry THF at 0° C. was treated with 2.59 mL (6.5 mmol) of n-butyl lithium (2.5 M in hexane). The mixture was kept at 0° C. for 30 min and at room temperature for 1 h, and 0.39 mL (2.94 mmol) of 2,6-dimethoxypyridine was added and the solution refluxed for 16 h. After cooling to room temperature, the mixture was poured into 1 M HCl and washed with toluene (3×). The aqueous layer was basified with 1 M NaOH and extracted with toluene (1×) and ethyl acetate (1×). The combined organic layers were dried (magnesium sulfate), filtered, and evaporated to give a yellow oil. Purification by flash silica gel chromatography with 9:1 chloroform:methanol gave 0.304 g (37%) of (7RS,9aSR)-7-hydroxymethyl-2-(6-methoxypyridin-2-yl)-2,3,4,6,7,8,9,9a-octahydro-1H-pyrido[1,2-a]pyrazine.

1. temperaturethe solution refluxed for 16 h
2. washwashed with toluene (3×)
3. extractionextracted with toluene (1×) and ethyl acetate (1×)
4. dry with materialThe combined organic layers were dried (magnesium sulfate)
5. filtrationfiltered
6. customevaporated
7. customto give a yellow oil
8. customPurification by flash silica gel chromatography with 9:1 chloroform