“Phosphite–Urea” Cooperative High-Turnover Catalysts for the Highly Selective Bromocyclization of Homogeranylarenes

Yasuhiro Sawamura, Hidefumi Nakatsuji, Akira Sakakura* and Kazuaki Ishihara* 
Chem. Sci.2013, 4 (11), 4181–4186.  (Published online: 02 Aug 2013) 
DOI: 10.1039/C3SC51432C 

Nucleophilic phosphite-urea cooperative high-turnover catalysts have been designed for the highly selective bromocyclization of homogeranylarenes.  The introduction of a urea moiety and bulky aryl groups in the catalyst inhibits decomposition of the catalyst and the generation of byproducts.  Only 0.5 mol% of the catalyst successfully promotes the bromocyclization of 4-homogeranyltoluene to give the desired product in 96% yield.