Process for the preparation of 3-unsubstituted indoles using methane sulfonic acid as an additional catalyst
US5157122A · kind A · utility
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Key dates
| Filing date | Jan 18, 1991 |
| Grant date | Oct 20, 1992 |
| Priority date | — |
| Expiry date | Jan 18, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D209/18
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
An indole having the formula I: ##STR1## is prepared by a Fischer-Indole reaction employing a mixture of phosphorous pentoxide and methane sulfonic acid as an acid catalyst. The reaction, which is optionally run in a co-solvent, provides 3-unsubstituted indoles in high yields with high regioselectivity. The indole thus prepared is an intermediate in the synthesis of leukotriene biosynthesis inhibitors.
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