Reaktion #2507828

Reaktionsgleichung

N-formylpiperidine

n-butyllithium

7-bromo-6-fluoro-3-pentylchroman

hydrochloric acid

→

6-fluoro-3-pentylchroman-7-carbaldehyde

Lösungsmittel

THF

n-hexane

THF

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Extraktionextracted three times with MTB ether
2. 2
   Waschenphases are washed with water and sat. sodium chloride soln
3. 3
   Trocknenand dried over sodium sulfate
4. 4
   Sonstigethe solvent is removed in vacuo
5. 5
   Sonstigethe residue is recrystallised from heptane at −25° C.

Vorschrift

15.5 g (51.5 mmol) of 7-bromo-6-fluoro-3-pentylchroman are dissolved in 85 ml of THF, and 35 ml (55.7 mmol) of a 15 percent solution of n-butyllithium in n-hexane are slowly added at −70° C. After 1 h, 6.3 ml (56.7 mmol) of N-formylpiperidine in 15 ml of THF are added dropwise, and the mixture is stirred for 1 h. The batch is subsequently allowed to thaw, added to water, acidified using dil. hydrochloric acid and extracted three times with MTB ether. The combined org. phases are washed with water and sat. sodium chloride soln. and dried over sodium sulfate, the solvent is removed in vacuo, and the residue is recrystallised from heptane at −25° C., giving 6-fluoro-3-pentylchroman-7-carbaldehyde as colourless crystals (Rf=0.4; 1-chlorobutane).

Quelle