Hydrogen‐Bond‐Mediated Asymmetric Cascade Reaction of Stable Sulfur Ylides with Nitroolefins: Scope, Application and Mechanism

Abstract

A hydrogen-bond-mediated asymmetric [4+1] annulation/rearrangement cascade of stable sulfur ylides and nitroolefins was developed. This reaction provides a facile route to enantioenriched 4,5-substituted oxazolidinones in moderate to excellent isolated yields (65-96 %) with excellent stereocontrol (up to more than 95:5 d.r. and 97:3 e.r.). This methodology was successfully applied to the concise synthesis of two bioactive molecules. The stereocontrolled modes and mechanism have been proposed to explain the origin of this stereochemistry.

Recent Progress in Organocatalytic Asymmetric Domino Transformations

“…Xiao and co‐workers successfully employed a combination of DMAP and C 2 ‐symmetric bisurea catalyst 531 in a stereoselective domino [4+1] annulation/rearrangement reaction for the synthesis of enantioenriched 4,5‐substituted oxazolidinones 530 from sulfur ylides 529 and nitroalkenes 76 (Scheme ) . The oxazolidinone products 530 were useful for synthesizing the natural products (+)‐ epi ‐cytoxazone ( 532 ) and valinoctin A ( 533 ) (Scheme ) …”

Asymmetric trapping of zwitterionic intermediates by sulphur ylides in a palladium-catalysed decarboxylation-cycloaddition sequence

“…More importantly, their synthetic potential has been well demonstrated in the synthesis of numerous bioactive natural products and pharmaceuticals 6,9,10 . In the past decade, the cycloaddition chemistry of sulphur ylides has evolved dramatically beyond three-membered rings, largely as a consequence of the valuable contributions made by Aggarwal and co-workers [11][12][13][14][15][16][17][18][19][20][21][22] , among others. For instance, in 2006, Aggarwal's group developed an elegant epoxy-annulation sequence reaction of vinyl sulphonium salts, which are important precursor of sulphur ylides, to rapidly convert aminoaldehydes, ketones and imines into epoxide-fused heterocycles (Fig.…”

“…In the same year, our own group developed a cascade reaction involving acyl-stabilized sulphur ylides and nitroolefins-specifically, a [4 þ 1] cycloaddition/rearrangement cascade (Fig. 1c) [15][16] . Notably, chiral H-bonding catalysis was successfully applied to this transformation, affording enantio-enriched oxazolidin-2-one products in good efficiency and selectivity.…”

“…Until very recently, p-Lewis-acid-gold complex-assisted cycloadditions of sulphur ylides with electron-neutral alkynes 17,18 and alkenes 19 have been sporadically reported. However, limited success has been achieved using catalytic asymmetric technologies to achieve asymmetric cycloadditions of sulphur ylides 16,[20][21][22] . In general, stoichiometric amounts of chiral auxiliaries or starting materials are required in the majority of reports to ensure good reaction efficiency and stereo-control.…”

“…In the past several years, we are interested in carbo-and heterocycle synthesis by using acyl-stabilized sulphur ylides 12,15,16,[27][28][29] . We herein describe an unprecedented Pdcatalysed DC reactions of vinyl benzoxazinanones by using sulphur ylides to highly enantioselectively trap Pd-stabilized zwitterionic intermediates I (Fig.…”