1020701-98-7Relevant academic research and scientific papers
Synthesis of substituted benzofurans and indoles by Zn-catalyzed tandem Sonogashira-cyclization strategy
Thankachan, Amrutha P.,Sindhu, Kallikkakam S.,Ujwaldev, Sankuviruthiyil M.,Anilkumar, Gopinathan
, p. 536 - 540 (2017)
Transition metal catalyzed cross-coupling reactions are one of the predominant strategies for the construction of heterocyclic structures which possess wide applications in the synthesis of natural products, pharmaceuticals, polymers, etc. Due to the vast importance of substituted benzofurans and indoles, numerous synthetic methodologies have been introduced for their synthesis. Among these methods, transition metal catalyzed cyclization reactions possess a unique position. In this manuscript, we disclose the first and efficient zinc-catalyzed protocol for the cyclization reactions of alkynes with 2-iodophenol and 2-iodoaniline leading to benzofurans and indoles respectively via a tandem Sonogashira coupling-cyclization process. Among the different metal catalysts, zinc has enormous potential due to its great availability, non-toxicity, eco-friendly and inexpensive nature. Zn(II) with N,N′-dimethylethylenediamine represents a suitable and efficient catalytic system for the desired tandem CC coupling-cyclization reactions, and a broad spectrum of functional groups are tolerated during the catalysis. A variety of substituted benzofurans and indoles have been successfully prepared in moderate to good yields under this new protocol.
Syntheses and pyrolyses of benzofuran analogues of α-oxo-o- quinodimethane. A study on vinylcarbene-cyclopropene rearrangement
Tseng, Pen-Wen,Yeh, Su-Wen,Chou, Chin-Hsing
, p. 3481 - 3485 (2008/09/21)
(Chemical Equation Presented) Flash vacuum pyrolyses (FVP) of benzoic 3-methyl-2-benzofurancarboxylic anhydride (12) and benzoic 2-methyl-3- benzofurancarboxylic anhydride (13) at 550°C and ca. 10-2 torr both give methylenebenzocyclobutenone (21) as the major product and indenone (22) as the minor one. A mechanism involving generation of α-oxo-o- quinodimethane 11 as the primary pyrolysis product from FVP of 13, followed by elimination of a CO molecule to give carbene 24, which undergoes a vinylcarbene-cyclopropene rearrangement and a ring contraction of the resulting carbene 23, is proposed to account for the observed results. The proposed mechanism is further supported by a deuterium-labeling study on FVP of (2-benzofuryl)methyl-α,α-d2 benzoate (28-d2).
