Enantioselective, Organocatalyzed, Intramolecular Aldol Lactonizations with Keto Acids Leading to Bi- and Tricyclic β-Lactones and Topology-Morphing Transformations
作者:Carolyn A. Leverett、Vikram C. Purohit、Daniel Romo
DOI:10.1002/anie.201004671
日期:2010.12.3
Quickly emerging complexity characterizes the asymmetric, nucleophile‐catalyzed aldollactonization (NCAL) process with ketoacid substrates and subsequent topology‐altering reactions. The utility of chiral cyclic isothiourea catalysts as nucleophilic promoters (Lewis bases) for desymmetrization reactions through scaleable NCAL processes is demonstrated (see picture; HBTM=homobenzotetramisole).
Dyotropic Rearrangements of Fused Tricyclic β-Lactones: Application to the Synthesis of (−)-Curcumanolide A and (−)-Curcumalactone
作者:Carolyn A. Leverett、Vikram C. Purohit、Alex G. Johnson、Rebecca L. Davis、Dean J. Tantillo、Daniel Romo
DOI:10.1021/ja303414a
日期:2012.8.15
Dyotropic rearrangements of fused, tricyclic β-lactones are described that proceed via unprecedented stereospecific, 1,2-acyl migrations delivering bridged, spiro-γ-butyrolactones. A unique example of this dyotropic process involves a fused bis-lactone possessing both β- and δ-lactone moieties which enabled rapid access to the core structures of curcumanolide A and curcumalactone. Our current mechanistic