Phosphazene-Base-Catalyzed Tandem Addition-Cyclization Reaction of o-Alkynylbenzaldehyde with Oxygen and Nitrogen Nucleophiles

Abstract

The tandem addition-cyclization reaction between o-alkynylbenzaldehyde and nucleophile catalyzed by P4- ^t Bu, a phosphazene base, is demonstrated. The nucleophilic cyclization is efficiently triggered not only by alcohols, including sterically demanding ones, but also by nitrogen nucleophiles, such as amide and pyrrole, under the influence of a catalytic amount of P4- ^t Bu. The method enables efficient access to isobenzofuran derivatives under mild conditions.

Key words

phosphazene - tandem reaction - cyclization - isobenzofuran - o-alkynylbenzaldehyde

References

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7

Other nucleophiles, such as phenol, 1-butanethiol, dimethyl malonate, and phenylacetylene did not give desired product.