1172612-81-5Relevant articles and documents
Asymmetric approach to the pentacyclic skeleton of Aspidosperma alkaloids via enantioselective intramolecular 1,3-dipolar cycloaddition of carbonyl ylides catalyzed by chiral dirhodium(II) carboxylates
Nambu, Hisanori,Hikime, Mayuka,Krishnamurthi, Janagiraman,Kamiya, Megumi,Shimada, Naoyuki,Hashimoto, Shunichi
supporting information; experimental part, p. 3675 - 3678 (2009/10/04)
This Letter describes asymmetric tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reaction of diazo imides containing a tethered indole catalyzed by chiral dirhodium(II) carboxylates as an approach to the pentacyclic skeleton of Aspidosperma alkaloids. The cycloaddition of carbonyl ylides derived from indolyl-substituted 2-diazo-5-imido-3-ketoesters under the influence of dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], Rh2(S-TCPTTL)4, provides cycloadducts in moderate yields and enantioselectivities of up to 66% ee as well as with perfect endo diastereoselectivity. This is the first example of asymmetric induction in an intramolecular cycloaddition of a carbonyl ylide across an indolyl π-bond.
