Abstract
Oligosulfonic acids are promising linker compounds for coordination polymers and metal-organic
frameworks, however, compared to their carboxylic acid congeners, often not readily
accessible by established synthetic routes. This Account highlights the synthesis
of recently developed aromatic and aliphatic di-, tri- and tetrasulfonic acids. While
multiple electrophilic sulfonations of aromatic substrates are rather limited, the
nucleophilic aromatic substitution including an intramolecular variant, the Newman–Kwart
rearrangement, allows the flexible introduction of up to four sulfur-containing moieties
at an aromatic ring. Sulfonic acids are then accessed by oxidation of thiols, thioethers,
or thioesters either directly with hydrogen peroxide or in two steps with chlorine
(generated in situ from N-chlorosuccinimide/hydrochloric acid) to furnish sulfochlorides which are subsequently
hydrolyzed. In the aliphatic series, secondary alcohols as starting materials are
converted into thioethers, thioesters, or thiocarbonates by nucleophilic substitutions,
which are also subsequently oxidized to furnish sulfonic acids.
1 Introduction
2 Electrophilic Aromatic Substitution
3 Nucleophilic Aromatic Substitution
3.1 Intermolecular SNAr
3.2 Intermolecular with Subsequent Oxidation
3.3 Intramolecular with Subsequent Oxidation
4 Nucleophilic Aliphatic Substitution with Subsequent Oxidation
5 Oxidation
5.1 Oxidation of Thiocarbonates
5.2 Oxidation of Thioethers
5.3 Oxidation of Thioesters
6 Thermolysis of Neopentylsulfonates
7 Functionalization via Diazonium Ions
8 Conclusion
Keywords
sulfur compounds - sulfonic acids - nucleophilic substitution - oxidation - protective
groups - linker molecules
