Pd(II)-mediated cyclization of o-allylbenzaldehydes in water: a novel synthesis of isocoumarins.

Po-Yuan Chen, Keng-Shiang Huang, Chin-Chuan Tsai, Tzu-Pin Wang, Eng-Chi Wang

Index: Org. Lett. 14(18) , 4930-3, (2012)

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Abstract

A novel, concise and efficient synthesis of substituted isocoumarins is disclosed. o-Allylbenzaldehydes prepared from isovanillin were mediated by PdCl(2)-CuCl(2) in water to undergo a domino reaction sequence, including 6-exo-trig cyclization, the addition of water, the elimination of PdHCl, the isomerization of carbon-carbon double bond, the oxidation of hemiacetals with the elimination of PdHCl, and regeneration of PdCl(2)in situ to yield a series of new substituted isocoumarins in high yields, in one pot.