Reaktion #80564

Reaktionsgleichung

NaCNBH3

HOAc

cyclobutanone

(R)-3-(N-cyclopentylamino)-8-fluoro-5- methoxy-3,4-dihydro-2H-1-benzopyran

→

title compound

Ausbeute 53.0%

(R)-3-(N-Cyclopentyl-N-cyclobutyl-amino)-8-fluoro-5-methoxy-3,4-dihydro-2H-1-benzopyran

Ausbeute 53.0%

Lösungsmittel

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONadded in portions at room temperature
2. 2
   workup.ADDITIONwas added
3. 3
   SonstigeThe solvent was evaporated
4. 4
   Extraktionthe residue worked up by extraction

Vorschrift

To a solution of (R)-3-(N-cyclopentylamino)-8-fluoro-5- methoxy-3,4-dihydro-2H-1-benzopyran (0.9 g, 3.4 mmol), HOAc (0.22 g, 3.6 mmol) and cyclobutanone (2g, 30 mmol) in methanol (25 mL), were NaCNBH3 (1 g, 16 mmol) added in portions at room temperature. After stirring for four days GC indicated 37% product. pH was adjusted to 5 (HOAc)and additional (1 g, 15 mmol) cyclobutanone was added. After stirring for further 6 days, GC indicated 64% conversion. The solvent was evaporated and the residue worked up by extraction. Flash chromatography (EtOAc/P-ether, 1+1), gave 0.53 g (53% yield) of the title compound as a colourless oil. GC/MS (70 eV) M=319 (3%).

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