Nucleophilic Substitution by Grignard Reagents on Sulfur Mustards

Abstract

With proper activation of the leaving group, sulfur mustards react with Grignard reagents with neighboring group participation of the sulfur atom. 2,6-Dichloro-9-thiabicyclo[3.3.1]nonane is especially useful in this regard, providing clean reactivity with organomagnesium nucleophiles on a topologically constrained scaffold.

The reaction of selenium dichloride with divinyl sulfide

“…It is known that a halogen atom is strongly activated in 2-haloethyl sulfides and selenides due to the anchimeric assistance effect with participation of sulfur or selenium atoms [25][26][27][28]. Nucleophilic substitution of halogen atoms in such compounds proceeds easily with a variety of nucleophiles.…”

A model SN2 reaction ‘on water’ does not show rate enhancement

“…In recent years there has been growing interest in the study of chemical reactions carried out 'on water' [1][2][3][4][5][6][7]. This refers to reactants with low solubility in water, which thus remain adsorbed at the air-water interface.…”

Addition of selenium dibromide to divinyl sulfide: spontaneous rearrangement of 2,6-dibromo-1,4-thiaselenane to 5-bromo-2-bromomethyl-1,3-thiaselenolane

“…The driving force for the rearrangement may be due to anchimeric assistance, [29][30][31] which causes high mobility of the bromine atom. This effect is important for the stabilization of cation 4, the assumed intermediate.…”

“…The halogen atom in 2-haloethyl sulfides and selenides is known to be strongly activated by the anchimeric assistance effect with participation of the sulfur or selenium atom. [29][30][31] Replacement of halogen atoms by a nucleophile in 2-haloethyl sulfides and selenides proceeds exceptionally easily. The formation of 3-membered thiirane and selenirane intermediates has been suggested to explain the considerable increase of the rate in nucleophilic substitution reactions.…”