Catalytic Enantioselective Alkylation of Sulfenate Anions to Chiral Heterocyclic Sulfoxides Using Halogenated Pentanidium Salts

Abstract

We report halogenated pentanidiums as phase-transfer catalysts for the asymmetric alkylation of sulfenate anions to various sulfoxides with high enantioselectivities (up to 99% ee) and yields (up to 99%). This approach gives access to enantioenriched heterocyclic sulfoxides that might not be compatible with strong oxidants or organometallic reagents. Computational studies have revealed that the multiple noncovalent interactions such as halogen bonds and nonclassical hydrogen bonds are involved.

Bisguanidinium dinuclear oxodiperoxomolybdosulfate ion pair-catalyzed enantioselective sulfoxidation

“…1)29. We were attracted to the low cost and easy accessibility of molybdate salts and thus we attempted to investigate the direct sulfoxidation of 2-sulfanyl acetate, by utilizing a catalytic amount of molybdate salts and aqueous H 2 O 2 as terminal oxidant.…”

“…We have recently developed pentanidium27282930 and dicationic bisguanidinium ( BG ) as efficient phase-transfer3132 and ion pair catalysts3334353637. We have utilized bisguanidinium permanganate ion pair catalyst for the enantioselective oxidation of alkenes38.…”

“…This ion pair catalyst is stable and isolatable or it can be generated in situ . In a continuation of our current efforts towards developing practical approaches to enantiopure sulfoxides294041, we report a simple and scalable methodology for enantioselective sulfoxidation using this ion pair catalyst42434445.…”

Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3‐Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums

“…Recently,o ur group has developed several structurally novel pentanidiums [9] as efficient phase-transfer catalysts [10] for asymmetric transformations.T of urther investigate the application of pentanidiums,v ariations of the catalyst are prepared and their behavior is examined in av ariety of reactions.H erein, we report the highly enantioselective conjugate addition of 3-alkyloxindoles to phenyl vinyl sulfone catalyzed by previously unreported pentanidiums ( Figure 2, 1b-e).…”

A New Role for Sulfenate Anions: Organocatalysis

“…Sulfenates are prochiral and have been probed for their chemical reactivity, [4] organometallic chemistry [6] and nucleophilic chemistry, [7] the latter primarily taking the form of alkylation at sulfur to provide sulfoxide. Recent work has focussed on enantio- [8,9] and diastereoselective sulfoxide formation. [10] The sulfenic acid has a pK a of about 6-7, making the sulfenate a reasonable leaving group.…”