Asymmetric Roadmap to Diverse Polycyclic Benzopyrans via Phosphine-Catalyzed Enantioselective [4+ 2]-Annulation Reaction

…, N Kesava-Reddy, C Golz, C Strohmann, K Kumar

Index: Waldmann, Herbert; Khedkar, Vivek; Dueckert, Heiko; Schuermann, Markus; Oppel, Iris M.; Kumar, Kamal Angewandte Chemie - International Edition, 2008 , vol. 47, # 36 p. 6869 - 6872

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Abstract

The catalytic addition of the amino acid derived bifunctional N-acylaminophosphine to an α- substituted allene ester generated a zwitterionic dipole that engaged the vinylogous ester function of 3-cyano-chromones in a [4+ 2] annulation reaction to deliver tetrahydroxanthones