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Paper | Special issue | Vol 37, No. 2, 1994, pp.759-774
Published online, 1st January, 1970
DOI: 10.3987/COM-93-S43
Synthesis of 2H-1-Benzopyrans from Aryllithium and α,β-Unsaturated Aldehydes

Raymundo Cruz-Almanza,* Francisco Pérez-Flores, and Cristina Lemini

*Instituto de Química, Universidad Nacional Autónama de México, Circuito Exterior, Ciudad Universitaria, Coyoacán 04510 Mexico, D.F., Mexico

Abstract

The synthesis of 2,2-dialkyl-2H-1-benzopyrans (23), (25), (27), (30), (31) and (29) was performed employing the 1,2-addition reaction of aryllithium salts to cyclocitral, 3-methyl-2-butenal, citral and farnesal respectively. Subsequent deprotection with a Mexican bentonitic earth (Tonsil) in wet acetone was followed by ring closure reaction as the key step. Interesting intermediate products were isolated in the formation of benzopyrans (30) and (31).