RESUMO
O-Sulfation is a vital post-translational modification in bioactive molecules, yet there are significant challenges with their synthesis. Dialkyl sulfates, such as dimethyl sulfate and diisopropyl sulfate are commonly used as alkylation agents in alkaline conditions, and result in the formation of sulfate byproducts. We report herein a general and robust approach to O-sulfation by harnessing the tunable reactivity of dimethyl sulfate or diisopropyl sulfate under tetrabutylammonium bisulfate activation. The versatility of this O-sulfation protocol is interrogated with a diverse range of alcohols, phenols and N-OH compounds, including carbohydrates, amino acids and natural products. The enhanced electrophilicity of the sulfur atom in dialkyl sulfates, facilitated by the interaction with bisulfate anion (HSO4-), accounts for this pioneering chemical reactivity. We envision that our method will be useful for application in the comprehension of biological functions and discovery of drugs.
RESUMO
Described here is the first example of solvent-promoted catalyst-free N-incorporation multicomponent domino reaction for the direct construction of novel π-extension [60]fullerene-fused dihydrocarbolines from simple hydrocarbons. This unprecedented transformation is proposed to proceed by a sequential N-incorporation/[4+2] cycloaddition/elimination process, involving multiple types of bond cleavage and formation in a single chemical operation. Mechanistic studies uncover that solvent is crucial for the success of the transformation, and multiple solvent-aided deprotonation and proton transfer are involved as key steps.