US5399713A
Expired / Lapsed
US
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Process for the production of 5,6-dihydroxyindolines
Assignee: Henkel AG and Co KGaA
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Filing: 1994-03-18
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Granted: 1995-03-21
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Expires: 2014-03-18
Abstract
Abstract Process for the production of 5,6-dihydroxyindolines by ether cleavage of corresponding ether procursors with aqueous hydrogen bromide and subsequent direct crystallization from the aqueous reaction mixture.
Inventors
- 👤 Georg Knuebel
- 👤 Guenther Konard
- 👤 Roswitha Michel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:05
CPC Classifications
C; C07; C07D; C07D209/00; C07D209/02; C07D209/04; C07D209/30; C07D209/42; C07D209/08
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
178 words
A process for the production of a 5,6-dihydroxyindoline of formula (I) ##STR3## in which R 1 and R 3 independently of one another represent hydrogen or a C 1-4 alkyl group and R 2 is hydrogen, a C 1-4 alkyl group, or a carboxyl group, comprising the steps of A) reacting an idoline ether of formula (II) or a salt thereof ##STR4## in which R 1 and R 3 independently of one another represent hydrogen or a C 1-4 alkyl group, R 4 and R 5 represent C 1-4 alkyl groups or, together with the oxygen atoms to which they are attached, form a C 1-4 alkylenedioxy group, and R 6 is hydrogen, a C 1-4 alkyl group or a group COOR 7 or CONR 7 R 8 and R 7 and R 8 are hydrogen or a C 1-4 alkyl group, with an aqueous solution of hydrobromic acid; B) cooling the resulting aqueous reaction mixture to crystallize the compound of formula I therefrom; and C) isolating the crystallized compound of formula I from the aqueous reaction mixture.
Claim 2
Dependent Claim
178 words
A process for the production of a 5,6-dihydroxyindoline of formula (I) ##STR3## in which R 1 and R 3 independently of one another represent hydrogen or a C 1-4 alkyl group and R 2 is hydrogen, a C 1-4 alkyl group, or a carboxyl group, comprising the steps of A) reacting an idoline ether of formula (II) or a salt thereof ##STR4## in which R 1 and R 3 independently of one another represent hydrogen or a C 1-4 alkyl group, R 4 and R 5 represent C 1-4 alkyl groups or, together with the oxygen atoms to which they are attached, form a C 1-4 alkylenedioxy group, and R 6 is hydrogen, a C 1-4 alkyl group or a group COOR 7 or CONR 7 R 8 and R 7 and R 8 are hydrogen or a C 1-4 alkyl group, with an aqueous solution of hydrobromic acid; B) cooling the resulting aqueous reaction mixture to crystallize the compound of formula I therefrom; and C) isolating the crystallized compound of formula I from the aqueous reaction mixture.
Claim 3
Dependent Claim
20 words
The process of claim 1 wherein in the indoline ether of formula II in step A, R 3 is hydrogen.
Claim 4
Dependent Claim
24 words
The process of claim 1 wherein in the indoline ether of formula II in step A, R 1 is hydrogen or a methyl group.
Claim 5
Dependent Claim
21 words
The process of claim 2 wherein in the indoline ether of formula II, R 1 is hydrogen or a methyl group.
Claim 6
Dependent Claim
10 words
The process of claim 4 wherein R 1 is hydrogen.
Claim 7
Dependent Claim
23 words
The process of claim 1 wherein in step A the indoline ether of formula II is in the form of the free amine.
Claim 8
Dependent Claim
37 words
The process of claim 1 wherein in the indoline ether of formula II in step A, R 4 and R 5 together with the oxygen atoms to which they are attached form a C 1-4 alkylenedioxy group.
Claim 9
Dependent Claim
22 words
The process of claim 1 wherein in step A the aqueous solution of hydrobromic acid contains from 40 to 62% hydrobromic acid.
Claim 10
Dependent Claim
27 words
The process of claim 1 wherein in step A the molar ratio of hydrobromic acid to the indoline ether of formula II is from 3:1 to 30:1.
Claim 11
Dependent Claim
14 words
The process of claim 9 wherein said molar ratio is from 5:1 to 15:1.
Claim 12
Dependent Claim
16 words
The process of claim 1 wherein in step A the reaction mixture is heated under reflux.
Claim 13
Dependent Claim
16 words
The process of claim 11 wherein the reaction mixture is heated under reflux for several hours.
Claim 14
Dependent Claim
15 words
The process of claim 1 wherein step C) is carried out by filtration under suction.
Claim 15
Dependent Claim
36 words
The process of claim 1 wherein in step A the molar ratio of hydrobromic acid to the indoline ether of formula II is from 3:1 to 30:1 and the reaction mixture is heated under reflux. .
Claim 16
Dependent Claim
20 words
The process of claim 14 wherein in the indoline ether of formula II R 1 and R 3 are hydrogen.
Claim 17
Dependent Claim
20 words
The process of claim 14 wherein the indoline either of formula II is in the form of the free amine.
Claim 18
Dependent Claim
14 words
The process of claim 14 wherein said molar ratio is from 5:1 to 15:1.
Claim 19
Dependent Claim
34 words
The process of claim 14 wherein in the indoline ether of formula II, R 4 and R 5 together with the oxygen atoms to which they are attached form a C 1-4 alkylenedioxy group.
References Cited (Backward Citations)
DE2905054A1
Cited
EP0462857A1
Cited
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