title: Phosphine-catalyzed enantioselective intramolecular [3+2] annulations to generate fused ring systems.
abstract: Substantial progress has been described in the development of asymmetric variants of the phosphine-catalyzed intermolecular [3+2] annulation of allenes with alkenes; however, there have not been corresponding advances for the intramolecular process, which can generate a higher level of complexity (an additional ring and stereocenter(s)). In this study, we describe the application of chiral phosphepine catalysts to address this challenge, thereby providing access to useful scaffolds that are found in bioactive compounds, including diquinane and quinolin-2-one derivatives, with very good stereoselectivity. The products of the [3+2] annulation can be readily transformed into structures that are even more stereochemically rich. Mechanistic studies are consistent with β addition of the phosphepine to the allene being the turnover-limiting step of the catalytic cycle, followed by a concerted [3+2] cycloaddition to the pendant olefin.
authors: †Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.|‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Sarah Yunmi
authors: SY
authors: Lee
authors: ‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Yuji
authors: Y
authors: Fujiwara
authors: †Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.|‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Atsuko
authors: A
authors: Nishiguchi
authors: †Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
authors: Marcin
authors: M
authors: Kalek
authors: †Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.|‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Gregory C
authors: GC
authors: Fu
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry; D002384:Catalysis; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D019086:Bridged Bicyclo Compounds, Heterocyclic; D010720:Phosphines; C044646:phosphine