反应详情

4-(1′-(tert-Butyl)-1′,2′,3′,6′-tetrahydro-3,4′-bipyridinyl-6-yl)-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester (0.44 g, 0.98 mmol) is placed in 60 ml of ethyl acetate in a Parr apparatus bottle. Platinum oxide (0.089 g, 0.39 mmol) is added. After stirring for 4 h under 32 psi H2, the catalyst is filtered off and rinsed with ethyl acetate. The filtrate is concentrated to dryness and then the residue is again stirred in 60 ml of ethyl acetate in the presence of 90 mg of platinum oxide under 35 psi for 18 h. The operation is repeated for 5 h and then 7 h. After filtering off the catalyst and rinsing with ethyl acetate, the filtrate is concentrated and then chromatographed on silica gel, elution being carried out with a methanol/aqueous ammonia gradient in dichloromethane varying from 100/0/0 to 9/1/0.1 (dichloro-methane/methanol/aqueous ammonia). 0.166 g of 4-(1′-(tert-butyl)-1′,2′,3′,4′,5′,6′-hexahydro-3,4′-bipyridinyl-6-yl)-3,4-dihydro-2H-quinoxaline-1-carboxylic acid tert-butyl ester is obtained.

1. filtrationthe catalyst is filtered off
2. washrinsed with ethyl acetate
3. concentrationThe filtrate is concentrated to dryness
4. stirringthe residue is again stirred in 60 ml of ethyl acetate in the presence of 90 mg of platinum oxide under 35 psi for 18 h
5. waitThe operation is repeated for 5 h
6. custom7 h
7. filtrationAfter filtering off the catalyst
8. washrinsing with ethyl acetate
9. concentrationthe filtrate is concentrated
10. customchromatographed on silica gel, elution