Straightforward Stereoselective Synthesis of Spiro‐epoxyoxindoles.

Abstract

Indole derivatives R 0140Straightforward Stereoselective Synthesis of Spiro-epoxyoxindoles. -The reaction proceeds via sulfonium ylides, prepared in situ, and affords the desired spirocyclic compounds with high diastereoselectivities. An asymmetric version is also presented. -(SCHULZ, V.; DAVOUST, M.; LEMARIE, M.; LOHIER, J.-F.; SOPKOVA DE OLIVEIRA SANTOS, J.; METZNER, P.; BRIERE*, J.-F.; Org. Lett. 9 (2007) 9, 1745-1748; Lab. Chim. Mol. Thio-Org., CNRS, Ec. Natl. Super. Ing., Univ. Caen, F-14050 Caen, Fr.; Eng.) -R. Steudel 36-100

Stereoselective synthesis and applications of spirocyclic oxindoles

“…64 Bencivenni was able to form axially enantioenriched 3-methylene oxindoles through a Knoevenagel condensation and, upon epoxidation, the high axially chiral enantioenrichment was maintained with a 5 : 1 dr. 65 The first report of an enantioselective epoxidation to form a spiro-epoxyoxindole was by Metzner and Briere in 2007, though only one example with 30% ee was given. 66 In 2011, Gasperi developed a moderately stereoselective epoxidation of 3-ylideneoxindoles using tert-butyl hydroperoxide with a prolinol catalyst. 67 More recently, Gasperi reported a full study of this work and disclosed a highly enantioselective epoxidation reaction of this type, when the oxindole protecting group was Boc, though the diastereoselectivity was poor.…”

Asymmetric Darzens Reaction of Isatins with Diazoacetamides Catalyzed by Chiral BINOL–Titanium Complex

“…1e In 2007, the group of Briere and Metzner first developed a stereoselective Darzens reaction between a stoichiometric amount of a C 2 symmetric chiral sulfide and αbromoacetamides, but the spiro-epoxyoxindole was achieved in only 30% ee. 3 In 2011, the research group of Gasperi succeeded in asymmetric epoxidation of α-ylideneoxindoles by using (S)α,α-diphenylprolinol as catalyst with tert-butylhydroperoxide as the oxidant, leading to the formation of epoxy-oxindoles with moderate to good stereoselectivities (up to 88% ee, up to 71:29 dr). 4 In 2014, Xiao's group reported an asymmetric synthesis of diethylacetamide-substituted epoxyoxindoles (>95:5 dr, up to 93% ee) by employing stoichiometric chiral sulfur ylides generated in situ from camphor-derived sulfonium salts.…”