Sulfonylation of 1,4-Diazabicyclo[2.2.2]octane: Charge-Transfer Complex Triggered C-N Bond Cleavage.

A novel charge-transfer complex triggered sulfonylation of 1,4-diazabicyclo[2.2.2]octane (DABCO) with mild reaction conditions has been developed. The formation of a charge-transfer complex between electron-withdrawing (hetero)aryl sulfonyl chloride and DABCO allows the synthesis of N-ethylated piperazine sulfonamide in good yields. The reaction has a high functional group tolerance. Spectroscopic studies confirmed the charge-transfer complex formation between sulfonyl chlorides and DABCO, which facilitates the C-N bond cleavage of DABCO.

Efficient synthesis of aliphatic sulfones by Mg mediated coupling reactions of sulfonyl chlorides and aliphatic halides.

Sulfonyl chlorides were reduced to anhydrous sulfinate salts with magnesium under sonication. These sulfinates were alkylated to sulfones with alkyl chlorides in the presence of catalytic sodium iodide under sonication. A variety of aliphatic sulfones was efficiently prepared by this one-pot two-step procedure.