Sulfinyl Group as an Intramolecular Nucleophile:  Synthesis of Bromohydrins from β-Methyl-γ,δ-unsaturated Sulfoxides with High 1,2-Asymmetric Induction

Abstract

Bromohydrins have been prepared from beta-methyl-gamma,delta-unsaturated sulfoxides with high regio- and stereoselectivity. The reaction proceeds via neighboring group participation of the sulfinyl moiety with inversion of sulfoxide configuration as proven by an (18)O labeling study and X-ray crystallography.

Stereoselective synthesis of the C13–C22 fragment of callystatin A by a non-aldol approach

“…The epimeric nature of 13, differing at sulfur, was confirmed by oxidation of 13 with m-CPBA to yield sulfone 14 (90% yield), which revealed a single set of signals in its 1 H NMR spectrum. In agreement with earlier results, 8 in this instance too, the methyl center alone influenced the stereochemical outcome of the reaction and sulfur chirality proved to be inconsequential. The stereochemical outcome of the reaction can be rationalized through the involvement of intermediates I and II.…”

“…Compound 5 can be obtained from γ,δ-unsaturated sulfoxide 6 by intramolecular oxidative functionalization employing the methodology developed in the group. 8 Unsaturated ester 6 can be traced to carbinol 7.…”

Flexible Approach to Stemona Alkaloids: Total Syntheses of (−)-Stemospironine and Three New Diastereoisomeric Analogs

“…Reaction of thiophenol, 71, with methyl bromoacetate, 72, and subsequent oxidation with NaIO 4 yielded sulfoxide 74. 50 The sulfoxide was treated with sodium hydride to afford the corresponding anion, which was subsequently alkylated with methyl 4-bromobutanoate, 76, rendering sulfoxide 75.…”

(+)‐Lentiginosine, a Potent and Selective Inhibitor of Amyloglucosidase: Synthetic Efforts and Disputes on Its Absolute Configuration

“…Unsaturated sulfoxide 105 was readily obtained by condensation of ester 104 with the α‐lithium derivative of 103 , followed by diastereoselective reduction of the resulting β‐ketosulfoxide. Sulfoxide 105 was converted into bromohydrin 106 by regio‐ and stereoselective methodology developed earlier by the same authors 63. After transformation of 106 into epoxide 107 , the nitrogen atom was introduced by a regioselective displacement with sodium azide.…”