Tetralone-2-formylpyrazoles: Valuable Precursors in the Tandem Cyclization for Asymmetric Synthesis of Highly
Liying Cui1, Changchun Yuan1, Yin Zheng2
1School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, P. R. China.
Abstract:
Tetralone-2-formylpyrazoles have been synthesized and applied as valuable precursors in a highly stereoselective tandem reaction with 2-nitrovinylphenols catalyzed by a chiral squaramide. This scenario provides a facile strategy to access various highly substituted spiro-3,4-dihydrocoumarins bearing contiguous quaternary and tertiary stereogenic centers with excellent stereoselectivities (>19:1 dr, up to 96:4 er). This reaction represents the first example of novel cyclic pyrazoleamide reagents derived from 1-tetralones being employed as trisubstituted 2-carbon synthons in catalytic asymmetric cyclizations.
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