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Homoleptic Zincate‐Promoted Room‐Temperature Halogen–Metal Exchange of Bromopyridines
Author(s) -
Chau Nguyet Trang Thanh,
Meyer Maxime,
Komagawa Shinsuke,
Chevallier Floris,
Fort Yves,
Uchiyama Masanobu,
Mongin Florence,
Gros Philippe C.
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001664
Subject(s) - homoleptic , zincate , chemistry , reagent , halogen , bromine , tetramethylethylenediamine , negishi coupling , metal , lithium (medication) , reactivity (psychology) , inorganic chemistry , silylation , medicinal chemistry , stoichiometry , organic chemistry , catalysis , medicine , alkyl , alternative medicine , pathology , zinc , endocrinology
Homoleptic lithium tri‐ and tetraalkyl zincates were reacted with a set of bromopyridines. Efficient and chemoselective bromine–metal exchanges were realized at room temperature with a substoichiometric amount of n Bu 4 ZnLi 2 ⋅TMEDA reagent (1/3 equiv; TMEDA= N , N , N′ , N′ ‐tetramethylethylenediamine). This reactivity contrasted with that of t Bu 4 ZnLi 2 ⋅TMEDA, which was inefficient below one equivalent. DFT calculations allowed us to rationalize the formation of N⋅⋅⋅Li stabilized polypyridyl zincates in the reaction. The one‐pot difunctionalization of dibromopyridines was also realized using the reagent stoichiometrically. The direct creation of CZn bonds in bromopyridines enabled us to perform efficient Negishi‐type cross‐couplings.