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An Indenone Synthesis Involving a New Aminotransfer Reaction and Its Application to Dibenzopentalene Synthesis
Author(s) -
Katsumoto Kenta,
Kitamura Chitoshi,
Kawase Takeshi
Publication year - 2011
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.201100575
Subject(s) - chemistry , quenching (fluorescence) , intramolecular force , yield (engineering) , reagent , transamination , alkyl , medicinal chemistry , combinatorial chemistry , reaction conditions , organic chemistry , catalysis , physics , materials science , quantum mechanics , metallurgy , fluorescence , enzyme
o ‐(Phenylethynyl)phenyllithiums, generated by treatment of o ‐(phenylethynyl)bromobenzenes with t BuLi, were quenched with N , N ‐dimethylcarboamides to afford various 2‐phenylindenone derivatives in moderate to good yields upon acidic workup. The choice of lithiation reagents was critical. When n ‐butyllithium was used the yields were reduced. The N ‐alkyl groups in the carboamides were also important: quenching with N , N ‐diethylbenzamides also afforded 2,3‐diphenylindenones as the sole isolated products, but quenching with N ‐benzoylpiperidine led to 2‐benzoyltolane in good yield. Control experiments revealed that the reactions proceed through a multi‐step reaction sequence involving a novel intramolecular transamination to the α‐acetylenic carbon of the alkynyl group. The method was applicable to the synthesis of dibenzopentalene derivatives as well as various indenone derivatives. A mechanism for the reaction is discussed.