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).
Concise Synthesis of Spirocyclic, Bridged γ-Butyrolactones via Stereospecific, Dyotropic Rearrangements of β-Lactones Involving 1,2-Acyl and δ-Lactone Migrations
作者:Vikram C. Purohit、Andrea S. Matla、Daniel Romo
DOI:10.1021/ja803579z
日期:2008.8.13
Dyotropic processes involving unprecedented 1,2-acyl migrations provide access to novel spirocyclic, bridged keto-gamma-lactones from a series of fused, tricyclic-beta-lactones, available via biscyclization of ketoacids including a new asymmetric variant. In addition, a spirocyclic bis-gamma-lactone was generated via a dyotropic process involving a 1,2-beta-lactone/sigma-lactone interchange. Overall