Ethanol → Picrate

HRID 1031900Notes

Reaction equation

HRID 1031900 reaction equation
[C:1]1([C:15]([O-])=[C:11]([N+]([O-])=O)[CH:10]=[C:6]([N+]([O-])=O)[CH:5]=1)[N+]([O-])=O.[C:17]1([C:31]([OH:32])=[C:27]([N+:28]([O-:30])=[O:29])[CH:26]=[C:22]([N+:23]([O-:25])=[O:24])[CH:21]=1)[N+:18]([O-:20])=[O:19].[CH2:33](O)C>>[CH2:33]1[C:15]2[C:1](=[CH:5][CH:6]=[CH:10][CH:11]=2)[CH:26]=[CH:27][NH:28]1.[C:27]1([C:31]([O-:32])=[C:17]([N+:18]([O-:20])=[O:19])[CH:21]=[C:22]([N+:23]([O-:25])=[O:24])[CH:26]=1)[N+:28]([O-:30])=[O:29]

Participants

5

Reactant 3

HCID 702EthanolHCID 6954Picric AcidHCID 4432340Picrate

Product 2

HCID 4225111,2-dihydroisoquinolineHCID 4432340PicrateYield 66%

Procedure

A solution of N-3,4-dimethoxybenzoyl-2-phenylethylamine (A1) (9.3 g, 0.033 mol) in 550 ml of tetrachloroethane was distilled to remove 75 ml of the solvent. The resulting solution was added in one portion to a cooled solution of P2O5 (44.5 g, 0.31 mol) in hexamethyldisiloxane which had been heated to reflux for 1 h under nitrogen to dissolve the P2O5. The reaction mixture was boiled with stirring under nitrogen for 2.5 h after which an additional 4.5 g (0.031 mol) of P2O5 was added. After 2 h further heating another portion of P2O5 (12 g, 0.085 mol) was added. Continued boiling for 30 min completed the reaction as indicated by tlc. The reaction was cooled in an ice bath and water (770 ml) was added with stirring. The layers were separated and the organic layer was washed with 500 ml of water. The combined aqueous extract was brought to pH 8 and extracted three times with 300 ml portions of ether. Removal of the ether afforded the crude dihydroisoquinoline A2 which was converted to the picrate by treatment with picric acid (8.7 g, 0.038 mol) in ethanol (105 ml). The crude picrate was crystallized from chloroform-ethanol to give A2 picrate (10.5 g, 66%) mp 148-151° dec. A2 picrate in methylene chloride was extracted three times with saturated NaHCO3 and eluted from a short column of basic alumina to give the title compound (6.0 g) which was dissolved in ethanol and treated with 2 ml. of concentrated hydrochloric acid. Evaporation of the ethanol solution gave the crude hydrochloride which was recrystallized from acetone to give pure 1-(3,4-dimethoxyphenyl)-3,4-dihydroisoquinoline hydrochloride (4.5 g 45%) mp 200-201°.

Workup

  1. customThe crude picrate was crystallized from chloroform-ethanol

Sources & evidence

ORD record
ord-f7e8e63244c041ac82489d600d44fa14
Source dataset
uspto-grants-1990_09
Patent number
US04956371

Reaction notes

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