Research Article

Synthetic Studies on Potent Marine Drugs: Synthesis and the Crystal Structure of 6-tert-butyl-4-phenyl-4H-chromene-2-carboxylic Acid

Table 2

Condensation of an β,γ-unsaturated α-ketoester 11 with phenol 12 a.

106908.table.002a

Entry111213Yield

1106908.table.002b106908.table.002f106908.table.002j43%b
211a12a13a37%
311a106908.table.002g0
411a106908.table.002h0
511a106908.table.002i106908.table.002k92%b
611a12d13b92%
7106908.table.002c12d106908.table.002l90%
8106908.table.002d12d106908.table.002m87%
9106908.table.002e12d106908.table.002n91%

General conditions: The mixture of AuCl3 (15.2 mg, 0.05 mmol) and AgOTf (38.6 mg, 0.15 mmol) in 1,2-dichloroethane (5 mL) was stirred at room temperature for 0.5 hour and then was added with a β,γ-unsaturated α-ketoester 11 (1.0 mmol) and a phenol 12 (1.0 mmol). The resulting mixture was stirred at reflux for 6 hours.
The crude products in 1,2-dichloroethane (5 mL) were filtered through Celite, added with a drop of concentrated sulfuric acid, and stirred at room temperature for 0.5 hour.