Preferential cross‐coupling of naphthol derivatives mediated by copper(II)

Abstract

Preferential cross‐coupling of differently N‐substituted amides of 3‐hydroxy‐2‐naphthoic acids 1 and 2 catalyzed by Cu(OH)Cl•TMEDA was observed. The reaction mechanism was investigated using mass spectrometry tools. It was shown that the complexation properties of the N‐substituent significantly influence the properties of the corresponding copper complexes of the deprotonated compounds ([(1‐H)Cu(TMEDA)]+ and [(2‐H)Cu(TMEDA)]+). Analysis of the fragmentation patterns of the copper complexes revealed that while the former is prone to the one electron oxidation of (1‐H)ˉ, the latter has a larger binding energy between (2‐H)ˉ and copper(II). Interplay between the abundance of the copper complexes and their reactivities explains the preferential cross‐coupling. The results are further supported by exploratory density functional theory calculations. Copyright © 2013 John Wiley & Sons, Ltd.

Crown Ether-Derived Chiral BINOL: Enantioselective Michael Addition of Alkenyl Boronic Acids to α,β-Unsaturated Ketones

“…It is worthy of being mentioned that the first achiral 3,3′bis(aza-crown ether)-substituted BINOL was synthesized by Roithováet al via Cu(II)-catalyzed cross-coupling of naphthol derivatives. 19 Here, we first synthesized the chiral 3,3′-bis(azacrown ether)-derived BINOL catalysts (S)-1a and (S)-1b in five steps, respectively, from 2,2′-bis(methoxymethoxy)-1,1′binaphthalene (S)-2 (Scheme 1). After iodination of (S)-2, the resulting BINOL (S)-3 underwent the palladium-catalyzed S u z u k i − M i y a u r a c o u p l i n g r e a c t i o n w i t h ( 4 -(methoxycarbonyl)phenyl)boronic acid to produce (S)-4 in 61% yield.…”