A series of Wieland-Miescher ketone analogues bearing highly functionalized substituents are efficiently constructed in high enantioselectivities and good yields using catalytic amounts of prolinamide and PPTS. We have successfully utilized this reaction as a key step to synthesize the tricyclic core of cylindricine type alkaloids.
efficient and practical protocol for the synthesis of both Wieland–Miescher ketone and Hajos–Parrishketone as well as their analogues. The reaction can be conducted in gram scale with 1% mol catalyst loading producing high enantioselectivity (up to 96% ee) and excellent yields (up to 98%). This procedure represents one of the most efficient methods for the synthesis of these versatile chiral building blocks
Efficient Solvent-Free Robinson Annulation Protocols for the Highly Enantioselective Synthesis of the Wieland-Miescher Ketone and Analogues
作者:Ben Bradshaw、Gorka Etxebarría-Jardi、Josep Bonjoch、Santiago F. Viózquez、Gabriela Guillena、Carmen Nájera
DOI:10.1002/adsc.200900321
日期:2009.10
A highly efficient (93% overall yield) and enantioselective (94% ee) synthesis of the Wieland–Miescher ketone (10-g scale) through a solvent-free Robinsonannulation procedure is reported. The process involves only 1 mol% triethylamine as the base in the initial Michael process and the organocatalyst N-tosyl-(Sa)-binam-L-prolinamide (2 mol%) and benzoic acid (0.5 mol%) for the intramolecular aldol