Process for preparation of fused pyrroles

Details Process for preparation of fused pyrroles Process for preparation of fused pyrroles

2005-03-29

2005-03-29

Richter, Johann (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

06872835

ABSTRACT:
The invention provides processes for the preparation of fused pyrroles, preferably indoles, which permit the use of inexpensive aromatic amines themselves as the raw material and attain high atomic efficiency and high regioselectivity. Specifically, a process for the preparation of fused pyrroles, e.g., indoles bearing methyl at the 3-position of pyrrole ring and R1(or R2) of the general formula (4) at the 2-position thereof, or 3,3-disubstituted indoles bearing R1and R2at the 3-position of pyrrole ring and methyl at the 2-position thereof, characterized by reacting an alkynol of the general formula (4) with an aromatic primary amine in the presence of a ruthenium complex, more preferably with an acid or an ammonium salt thereof being made to coexist.[In the general formula (4), R1and R2are each independently hydrogen, optionally substituted alkyl, or optionally substituted aryl, or alternatively R1and R2may be united to form an alkylene chain.]

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M. Tokunaga, et al., “A practical one-pot synthesis of 2, 3-disubstituted indoles from unactivated anilines”,Tetrahedron Letters42 (2001) 3865-3868.
M. Tokunaga, et al., “Ruthenium-Catalyzed Intermolecular Hydroamination of Terminal Alkynes with Anilines: A Practical Synthesis of Aromatic Ketimines”,Angew. Chem. Int. Ed 111, (1999) 3408-3411, 1433-7851/99/3821-3224.
M. Fagnola et al.,Tetrahedron Letters, 13:2307-2310 (1997).
J. Mahanty et al.,Tetrahedron, 39:13397-13418 (1997).

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