Enantioselective and aerobic oxidative coupling of 2-naphthol derivatives using chiral dinuclear vanadium(V) complex in water

Abstract

a b s t r a c tThe enantioselective oxidative coupling of 2-naphthols in water was established using dinuclear vanadium(V/IV) catalysis with O 2 as the sole co-oxidant. In the vanadium-catalyzed reaction, the corresponding coupling products were obtained in good to excellent yields with up to 94% enantiomeric excess. In water, racemization of the coupling product was suppressed even at high temperature (70°C).

Synthetic Applications of Oxidative Aromatic Coupling—From Biphenols to Nanographenes

“…Dinuclear vanadium catalysts are among the most efficient examples for the enantioselective syntheses of BINOLs, useful even in the dimerization of PAH‐based phenols . However, recent studies have revealed that chiral mononuclear vanadium(V) catalysts are also useful.…”

Base-promoted lipase-catalyzed kinetic resolution of atropisomeric 1,1′-biaryl-2,2′-diols

“…The spectroscopic data are in good agreement with those reported. 28 Its optical purity (99% ee) was determined by chiral HPLC analysis at 20 C using a CHIRALPAK IC-3 column (hexanes/2-propanol ¼ 97.5 : 2.5; ow rate: 1.0 mL min À1 ; retention times: 29.2 min for (R)-1b; 31.6 min for (S)-1b). 6H).…”

Enantioselective vanadium-catalyzed transformations. An update

“…Especially, chiral vanadium complexes have been successfully applied to catalyze these reactions. For example, in 2015 Sasai et al described the enantioselective oxidative coupling of 2-naphthols performed in water in the presence of dinuclear vanadium complex 1 [9]. This amino acid-derived Schiff base catalyst was earlier developed by these authors starting from VOCl 3 , (S)-tert-leucine and (R)-3,3 0 -diformyl-2,2 0 -dihydroxy-1,1 0 -b inaphthyl [10].…”

“…As depicted in Scheme 28, the process consisted in an enantioselective domino oxidative coupling/intramolecular cyclization reaction of 2-hydroxybenzo [c]phenanthrenes 49a-i promoted by chiral preformed binaphthyl vanadium catalyst 50. The reaction was performed at 50°C under O 2 atmosphere in tetrachloromethane as solvent and led to the corresponding chiral oxa [9]helicenes 51a-i in good to high yields (56-86%) and moderate to excellent enantioselectivities (44-94% ee). After a first oxidative coupling of 49a-i which gave intermediate 52, an intramolecular cyclization occurred to afford domino products 51a-i.…”