Sulfimidation of thioether groups--a versatile method for modifying and linking thia/oxa crowns.

Reaction of the mixed thioether/ether crowns [9]aneO2S , [12]aneO3S and [18]aneO4S2 with one mol. equivalent of the aminating agent MSH (o-mesitylsulfonylhydroxylamine) in Et2O results in the formation of the mono-sulfimidated systems {[9]aneO2(S=NH2)}+, {[12]aneO3(S=NH2)}+ and {[18]aneO4S(S=NH2)}+, while using two mol. equivalents of MSH with gives the disulfimidium cation {[18]aneO4(S=NH2)2}2+. All of these species have been isolated in good yields as the [mesSO3]- (mes=2,4,6-Me3C6H2) salts and can be readily converted to the [BPh4]- salts by metathesis with Na[BPh4]. Treatment of or with lithium diisopropylamide (LDA) and N-bromosuccinimide (NBS) at -78 degrees C, followed by addition of a further equivalent of the parent thia/oxa crown, gives monocationic N-bridged sulfimide bicyclic compounds ( and respectively), in which the crowns are linked by the sulfimidic nitrogen. Reaction of with LDA and NBS leads to formation of the {([18]aneO4S2)N}+ cation which exhibits an intramolecular S-N-S bridge. Crystallographic studies on representative examples of each compound type are described, together with their spectroscopic properties.