Cycloisomerization of Olefins in Water

Preparative chemical reactions that occur efficiently under dilute, buffered, aqueous conditions in the presence of biomolecules find application in ligation, peptide synthesis, polynucleotide synthesis and sequencing. However, the identification of functional groups or reagents that are mutually reactive with one another, but unreactive with biopolymers and water, is challenging. Here we show that cobalt catalysts will react with the alkenes of unsaturated tertiary amines under dilute, aqueous, buffered conditions and promote efficient cycloisomerization, in many cases mediating a formal Friedel-Crafts reaction. We find the constraining conditions of biorthogonal chemistry to be beneficial for reaction efficiency as we obtain superior conversion at low catalyst concentration and maintain competent rates in dilute conditions. The efficiency at high dilution in the presence of buffer and nucleobases suggests that these conditions may find use on or in the presence of biomolecules.