Molecules, Vol. 29, Pages 1445: Rearrangement of Arylsulfamates and Sulfates to Para-Sulfonyl Anilines and Phenols

Molecules, Vol. 29, Pages 1445: Rearrangement of Arylsulfamates and Sulfates to Para-Sulfonyl Anilines and Phenols Molecules doi: 10.3390/molecules29071445 Authors: Yifei Zhou Alan M. Jones The C(sp2)-aryl sulfonate functional group is found in bioactive molecules, but their synthesis can involve extreme temperatures (>190 °C or flash vacuum pyrolysis) and strongly acidic reaction conditions. Inspired by the 1917 Tyrer industrial process for a sulfa dye that involved an aniline N(sp2)-SO3 intermediate en route to a C(sp2)-SO3 rearranged product, we investigated tributylsulfoammonium betaine (TBSAB) as a milder N-sulfamation to C-sulfonate relay reagent. Initial investigations of a stepwise route involving TBSAB on selected anilines at room temperature enabled the isolation of N(sp2)-sulfamate. Subsequent thermal rearrangement demonstrated the intermediary of a sulfamate en route to the sulfonate; however, it was low-yielding. Investigation of the N-sulfamate to C--sulfonate mechanism through control experiments with variation at the heteroatom positions and kinetic isotope experiments (KIEH/D) confirmed the formation of a key N(sp2)-SO3 intermediate and further confirmed an intermolecular mechanism. Furthermore, compounds without an accessible nitrogen (or oxygen) lone pair did not undergo sulfamation- (or sulfation) -to-sulfonation under these conditions. A one-pot sulfamation and thermal sulfonation reaction was ultimately developed and expl...
Source: Molecules - Category: Chemistry Authors: Tags: Article Source Type: research