Sulfuric Acid → 6-Chloro-2-methyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole

HRID 717796Notes

Reaction equation

Cl.[Cl:2][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=1[NH:9]N.OS(O)(=O)=O.[CH3:16][N:17]1[CH2:22][CH2:21][C:20](=O)[CH2:19][CH2:18]1>O1CCOCC1>[Cl:2][C:3]1[C:4]2[NH:9][C:20]3[CH2:21][CH2:22][N:17]([CH3:16])[CH2:18][C:19]=3[C:5]=2[CH:6]=[CH:7][CH:8]=1

Participants

Conditions

Temperature: 80 °C

Procedure

To a suspension of 2-chlorophenyl hydrazine hydrochloride (19.7 g, 0.110 mol) in dioxane (190 mL) at RT was added conc. H2SO4 (8 mL, 0.150 mol) dropwise and the reaction mixture was stirred for 10 min. To this was added N-methyl-4-piperidone (17.53 g, 0.154 mol) and the reaction mixture was stirred at RT for 20 min, then heated at 80° C. for 4 h. The reaction was monitored by TLC. The solvent was evaporated and pH adjusted to pH 8-9 with saturated sodium bicarbonate solution. The product was extracted with EtOAc (3×300 mL). The combined organic layer was washed with water and brine, dried over sodium sulfate, and concentrated under vacuum. The crude product was purified by recrystallization (Ether/Hexane). The filtered solid was dried in vacuo to obtain 7.5 g of product as a brown solid. 1H NMR (CDCl3, freebase) d (ppm): 8.10 (bs, 1H), 7.30 (d, 1H), 7.10 (d, 1H), 7.0 (t, 1H), 3.62 (s, 2H), 2.90 (m, 2H), 2.82 (m, 2H), 2.38 (s, 3H).

Workup

stirringthe reaction mixture was stirred at RT for 20 min
customThe solvent was evaporated
extractionThe product was extracted with EtOAc (3×300 mL)
washThe combined organic layer was washed with water and brine
dry with materialdried over sodium sulfate
concentrationconcentrated under vacuum
customThe crude product was purified by recrystallization (Ether/Hexane)
customThe filtered solid was dried in vacuo

Sources & evidence

ORD record: ord-24ea880e26d44712858cc15187d6e6f6
Source dataset: uspto-grants-2015_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09193728B2

Reaction notes

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