3-phenyl-1H-indene (Prepared in House by method of SP696)

3-chlorobenzaldehyde (Oakwood Chemical, 95%)

1,8-Diazabicyclo[5.4.0]undec-7-ene "DBU" (TCI, 98%)

2-MeTHF (Sigma-Aldrich, HPLC grade)

The synthesis was performed under ambient atmosphere. To a microwave reaction vial charged with indene  (0.204 g, 1.06 mmol) was added 3-chlorobenzaldehyde (0.154 g, 1.10 mmol), DBU  (0.172 g, 1.13 mmol), and 2-MeTHF (2 mL, 0.53 M). The vial was then heated via variable watt microwave irradiation to 60 °C for 10 minutes with a 30 second pre-stirring period. Upon completion a yellow sheen was observed on the sides of the vial. The reaction mixture was quenched using a silica plug. The solvent was removed under reduced pressure. The crude mixture was purified via preparative chromatography, (90:10 hexane:toluene) yielding the title compound as a crimson red solid, (0.190 g, 58%).

The synthesis was also performed on a 100 mg scale (indene) yielding 90 mg of the title compound (55%). 

3-chlorobenzaldehyde should be added before the DBU, and the time between the addition of the DBU and microwave heating should be minimized in order to maximize yield.

¹H NMR (CDCl₃, 500 MHz): δ ppm 7.06 (s, 1H), 7.29-7.36 (m, 4H), 7.39-7.44 (m, 2H), 7.46-7.51 (m, 3H), 7.59-7.62 (m, 2H), 7.69-7.75 (m, 3H)

 ¹³C NMR (CDCl₃, 125 MHz): δ ppm 119.5, 120.5, 122.5, 125.7, 126.2, 127.60, 127.7, 128.1, 128.2, 128.31,128.6, 129.8, 129.9, 134.6, 135.4, 138.6, 138.8, 140.3, 140.8, 148.3

GC-MS EI [M.+]: Predicted: 314.09, Actual: 314;   Predicted: 315.09 Actual: 315; Predicted: 316.08,  Actual: 316¹