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.