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Novel Furo‐pyridine Derivatives via Sonogashira Reactions of Functionalized Pyridines
Author(s) -
Lechel Tilman,
Dash Jyotirmayee,
Brüdgam Irene,
Reißig HansUlrich
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200800398
Subject(s) - chemistry , sonogashira coupling , pyridine , iodine monochloride , halogenation , iodine , combinatorial chemistry , derivative (finance) , medicinal chemistry , palladium , organic chemistry , catalysis , economics , financial economics
A series of 4‐pyridyl nonaflates was coupled with several terminal alkynes to efficiently provide new 4‐alkynyl‐substituted 3‐alkoxypyridine derivatives. Apt conditions were developed for their conversion into furo[2,3‐ c ]pyridines. Sonogashira reactions of 4‐alkoxy‐substituted 3‐pyridyl nonaflates allowed an access to regioisomeric furo[3,2‐ c ]pyridines. For both types of alkynyl‐substituted alkoxypyridinesan alternative method for cyclization employing iodine monochloride furnished iodinated furo[2,3‐ c ]‐ or furo[3,2‐ c ]pyridines, which can undergo a second palladium‐catalyzed step. Iodination of 4‐hydroxypyridine derivative 24 with iodine afforded a pentasubstituted pyridine which after Sonogashira reaction immediately undergoes a cyclization to furo‐pyridine 25 . Thus, three different types of furo‐pyridines can be prepared starting from one precursor. Several compounds prepared are fluorescent and show strong Stokes shifts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)