Trimethylamine → 1,2,3,9-Tetrahydro-9-methyl-3-methylene-4H-carbazol-4-one

HRID 36773

Reaction equation

HRID 36773 reaction equation
CC1N([CH2:7][CH:8]2[C:21](=[O:22])[C:12]3[C:13]4[CH:14]=[CH:15][CH:16]=[CH:17][C:18]=4[N:19]([CH3:20])[C:11]=3[CH2:10][CH2:9]2)C=CN=1.CI.CN(C)C>>[CH3:20][N:19]1[C:11]2[CH2:10][CH2:9][C:8](=[CH2:7])[C:21](=[O:22])[C:12]=2[C:13]2[C:18]1=[CH:17][CH:16]=[CH:15][CH:14]=2

Participants

4

Reactant 3

HCID 1146TrimethylamineHCID 4595OndansetronHCID 6328Methyl iodide

Product 1

HCID 117905051,2,3,9-Tetrahydro-9-methyl-3-methylene-4H-carbazol-4-one

Procedure

Peculiarly, the above-said patent specification indicates this tertiary amine to be known per se and, in addition, ondansetron can be prepared therefrom in an other way, too. After quaternizing the tertiary amine with methyl iodide, trimethylamine is split off from the obtained methoiodide by Hofmann's elimination reaction to give 9-methyl-3-methylene-1,2,3,9-tetrahydro-4H-carbazol-4-one. The thus-obtained electrophilic conjugated enone is subjected to an addition reaction with 2-methylimidazole (see Example 8 of the specification). The surprisingly moderate yield of 43.2% of the reaction shows that the significance of this simple direct addition, starting from the separated enone, should not be overestimated.

Workup

  1. customcan be prepared
  2. customis split off from the obtained methoiodide by Hofmann's elimination reaction

Sources & evidence

ORD record
ord-c36be793b02543d6ad007afe1cf74764
Source dataset
uspto-grants-1995_05
Patent number
US05416221

Linked notes

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