Indole → 1-Aminoindole

Participants

Reaction Conditions

Reaction Steps

Step 1 —Preparation of HOSA/indole solution: A 50-gal glass lined steel reactor is charged with 120.2 kg (116.3 L) NMP under nitrogen purge and slight exhaust, while the reactor temperature is maintained at 19–23° C. With agitation (ca. 130 rpm), charge 33.8 kg (32.8 kg corrected for 97% purity) HOSA in three portions (ca. 15.8 kg, 9.0 kg and 9.0 kg) through the manhole ca. 15–30 min apart. Expect an initial exotherm of 10–15° C. temperature rise. Circulate chilled water through the jacket or use gentle jacket heating to maintain a pot temperature of 20–35° C. (preferably 30–35° C. to facilitate dissolution). Expect dissolution after 1–2 h agitation. Cool the contents of the reactor to a temperature of about 20° C. (10–25° C.) and charge 15.8 kg (15.6 kg corrected for 99% purity) indole through the manhole. After dissolution (several minutes), cool the contents of the reactor to a temperature of about 0–5° C. (−5 to 15° C.), reduce agitation to about 50 rpm and then maintain a temperature at around 0–5° C. (−5 to 15° C.) for the remainder of the process. Step 2—Preparation of the potassium tert-butoxide solution: A 50-gal glass-lined steel reactor equipped with an empty condenser line is charged with 122.6 kg (118.7) NMP under nitrogen purge and slight exhaust, while maintaining the reactor temperature around 17–19° C. (15–22° C.). Charge 67.0 kg (63.7 kg corrected for 95% purity) potassium tert-butoxide (KOtBu) through the manhole at agitation ca. 150 rpm (100–200 rpm). Observe slight exotherm to 20–25° C. Cool if necessary to keep temperature below 25° C. After dissolution is attained (within 15–60 min), stir at about 50 rpm and at a temperature of about 17–25° C. for the remainder of the process. Step 3—Amination: A 150-gal glass-lined steel reactor is charged with 47.0 kg (45.5 L) NMP under nitrogen purge and slight exhaust, and cool to 10–22° C. with agitation at about 180 rpm. Charge an initial amount of about 0.05 equiv of KOtBu solution from step 2 (6.7 mole, total 2.2 kg of the solution). Then simultaneously pump the two solutions prepared above in steps 1 and 2 at the following rates: HOSA/indole solution from step 1 at a rate of 0.8 L/min=0.9 kg/min for 187.4 min total time; and KOtBu solution from step 2 at a rate of 1.0 L/min=1.0 kg/min for 187.4 min total time through sparging tubes (⅜-in o.d. 304 SS tubing) inserted in nozzles at opposite sides of the reactor head (about 180 degrees apart) while maintaining good agitation (>180 rpm) and maintaining the reaction temperature at about 15–30° C., preferably 24–30° C., using chilled water cooling. Monitor the progress of the reaction by withdrawing samples of the reaction mixture for HPLC assay, as further detailed below, at 0.5 equiv. intervals of HOSA charged (every 43 min, 35 sec during the simultaneous reagent feeds). Continue the simultaneous proportional feed until all of the reagents (133.5 mole scale) have been charged and the amination is judged complete as evidenced by HPLC assay. Rinse both of the reactors from steps 1 and 2 with L NMP each and pump the rinse to the 150-gal reactor in this step. The batch from this step is then used, as is, for the next step in the preparation of N-propylidene-1H-indol-1-amine.

Provenance & Evidence