Reaktion #1523395

Reaktionsgleichung

bromine

bromine

bromine

Acetic acid

Pyridine

DCHA

(+/−)-[5-bromo-4-(4-chlorobenzyl)-7-fluoro-1,2,3,4-tetrahydrocyclopenta[b]indol-3-yl]acetic acid

→

(+/−)-(5-bromo-7-fluoro-1,2,3,4-tetrahydrocyclopenta[b]indol-3-yl)acetic acid

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturmaintaining the temperature between −20° C. and −15° C. (
2. 2
   workup.ADDITION) After completion of the addition
3. 3
   Sonstigewas aged for one additional hour at −15° C
4. 4
   Sonstige(about −15° C. to −10° C.)
5. 5
   workup.WAITThe whole operation takes around 30 to 45 minutes

Vorschrift

A slurry of the DCHA salt from Step 1 above in dichloromethane (0.241 M solution) was cooled to −20 to −15° C. Pyridine (2 eq.) was added in one shot and to the slurry was added dropwise bromine (2.5 eq.) over 30 to 45 minutes maintaining the temperature between −20° C. and −15° C. (At about ⅓ addition of bromine, the reaction mixture was thick and an efficient stirring was needed. Eventually, at about ½ addition of bromine, the mixture became “loose” again.) After completion of the addition, the reaction mixture was aged for one additional hour at −15° C. Acetic acid (3.04 eq.) was then added over 5 minutes and zinc dust (3.04 eq.) was added portion wise. (A portion of zinc was added at −15° C. and the mixture was aged for about 5 minutes to ensure that the exotherm was going (about −15° C. to −10° C.)). This operation was repeated with about 5 shots of zinc over about 30 min. When no more exotherm was observed, the remaining zinc was added faster. The whole operation takes around 30 to 45 minutes.

Quelle