Regioselective alkynylation followed by Suzuki coupling of 2,4-dichloroquinoline: Synthesis of 2-alkynyl- 4-arylquinolines

• Ellanki A. Reddy,
• Aminul Islam,
• K. Mukkanti,
• Venkanna Bandameedi,
• Dipal R. Bhowmik and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 32, doi:10.3762/bjoc.5.32

• ) 10.3762/bjoc.5.32 Abstract A two step synthesis of 2-alkynyl-4-arylquinolines has been accomplished via Pd/C-mediated regioselective C-2 alkynylation of 2,4-dichloroquinoline in water followed by Suzuki coupling at C-4 of the resulting 4-chloro derivative. Keywords: alkyne; boronic acid; catalysis; 2,4

• biological significance we have reported Pd/C-mediated regioselective C-2 alkynylation of 2,4-dichloroquinoline in water [6]. However, only one example of regioselective C-2 alkynylation was reported and no detailed study has been carried out previously. Herein we report the preparation of a series of 2

• Discussion A number of 2-alkynyl-4-chloroquinolines (3) were prepared via coupling of 2,4-dichloroquinoline (1) in the presence of 10% Pd/C (10 mol%), PPh3 (20 mol%) and CuI (5 mol%) as a catalyst system in water. The results are presented in Table 1. Both aryl and alkyl substituted terminal alkynes