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A Convenient Synthetic Route to Spiro[indole‐3,4′‐piperidin]‐2‐ones
Author(s) -
Freund Ralf,
Mederski Werner W. K. R.
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20000607)83:6<1247::aid-hlca1247>3.0.co;2-1
Subject(s) - chemistry , piperidine , intramolecular force , yield (engineering) , indole test , nitro , medicinal chemistry , catalysis , stereochemistry , combinatorial chemistry , organic chemistry , materials science , alkyl , metallurgy
Starting from 1‐[( tert ‐butoxy)carbonyl]piperidine‐4‐carboxylic acid and 2‐bromoaniline, the spiro[indole‐3,4′‐piperidin]‐2‐one system was obtained in three high‐yielding steps: anilide formation, N (1)‐protection, and intramolecular cyclization under Pd catalysis as the key reaction. The preparation of the corresponding 2‐bromoanilide was studied. In extension, the same sequence was developed with 4‐methyl‐ and 4‐nitro‐2‐bromoaniline. In the key step, the NO 2 group led to a rather diminished yield. The transformation of the protected spiro[indole‐3,4′‐piperidin]‐2‐one to the corresponding unprotected dihydroindoles is discussed.