Enantioselective Bromocyclization of 2-Gernaylphenols Induced by Chiral Phosphite-Urea Bifunctional Catalysts
Yasuhiro Sawamura, Yoshihiro Ogura, Hidefumi Nakatsuji, Akira Sakakura* and Kazuki Ishihara*
Chem. Commun.2016, 52 (36), 6068–6071. (Published online: Mar 18, 2016)
DOI: 10.1039/C6CC00229C
Chiral phosphite-urea bifunctional catalysts have been developed for the first enantioselective bromocyclization of 2-geranylphenols with N-bromophthalimide (NBP). The chiral triaryl phosphite moiety activates NBP to generate a bromophosphonium ion. On the other hand, the urea moiety interacts with a hydroxyl group of the substrate through hydrogen bonding interactions. Enantioselectivity is effectively induced through two-point attractive interactions between the catalyst and substrate.