Dibromotetrachloroethane (C(2)Br(2)Cl(4)) is demonstrated as a halogenating reagent for the one-pot conversion of sulfones to alkenes by way of the Ramberg-Bäcklund rearrangement. Dibromotetrachloroethane successfully replaces known ozone depleting agents CCl(4), CBr(2)F(2) and C(2)Br(2)F(4). A formal synthesis of E-resveratrol is demonstrated using C(2)Br(2)Cl(4).

A series of Boc-protected β-amino sulfoxides were prepared by the reaction of arenesulfenate anions with chiral Boc-protected β-amino iodides. The stereoselective substitution reaction is believed to arise through precoordination of the sulfenate counterion with the nitrogen lone pair of the electrophile.

Building from a previous communication, the reaction of sulfenate anions with chiral N-Boc-protected β-substituted β-amino iodides was evaluated as a conceptually different synthetic approach to chiral β-substituted β-amino sulfoxides. Using arenesulfenates, yields typically ranged from 71% to 92%, and dr's were often near 9:1. Alkanesulfenates proved less reactive, delivering lower yields and dr's. 1-Alkenesulfenates demonstrated high reactivity, returning chemical yields of 60-86% and dr's often close to 9:1 and as high as 95:5. (S)-β-Amino iodide electrophiles yielded (R(S),S(C))-β-amino sulfoxides, whereas (R)-amino iodides afford (S(S),R(C))-β-amino sulfoxides. The absolute configuration of the products makes the sulfenate protocol complementary to other existing preparations, including the commonly employed sulfoxidation of β-amino sulfides. The reactivity of N-Boc-protected 2-benzyl-2-aminoethyl iodide was found to be superior to the less sterically encumbered n-butyl iodide. A transition state model is proposed to account for the stereochemistry of the products and also for the high reactivity of the electrophile. Overall, the chemistry represents a new means of introducing sulfur stereogenicity in a molecule.

No abstract

Intramolecular conjugate additions of homochiral (E)-1-alkenyl 2-aminoalkyl sulfoxides and sulfones were investigated. The relative position of the 3,5-substituents of the resulting 1,4-thiazane oxides was found to be dependent on the oxidation state of the sulfur atom, demonstrating a simple and highly stereodivergent synthetic protocol. Selected cis- and trans-3,5-disubstituted 1,4-thiazane dioxides were converted to cis- and trans-2,5-disubstituted pyrrolidines, known ant venom alkaloids.