“…Furthermore, although P(RNCH 2 CH 2 ) 3 N as an efficient promoter (Kisanga et al, 2002) has been introduced recently, the reaction has to be conducted in benzene or isobutyronitrile, which are not environmentally friendly solvents. Alternatively, coumarins could also be synthesized by other methods including Pechmann (Gu et al, 2005;Fang et al, 2008), Perkin (Camur and Bulut, 2008), Reformatsky (Chen et al, 2005), Wittig (Yavari et al, 1998) reactions, and by flash vacuum pyrolysis (Cartwright and McNab, 1997).…”