The readily available and enzymatically derived cis-1,2-dihydrocatechol 4 has been elaborated, over 11 steps including an Overman rearrangement, into the non-natural enantiomer, (-)-1, of the alkaloid lycoricidine [(+)-1]. Related chemistries have provided analogues 18, 19, and 26.

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A concise asymmetric approach to the indeno-tetrahydropyridine core of the unusual alkaloid haouamine B allowed for an investigation of a biomimetic oxidative phenol coupling as a proposed biosynthetic step, and ultimately provided access to the published structure of the natural product. As a consequence of our synthetic studies, the structure of haouamine B has been revised.

Non-enzymatic posttranslational modifications (nPTMs) affect at least ∼30 % of human proteins, but our understanding of their impact on protein structure and function is limited. Studies of nPTMs are difficult because many modifications are not included in common chemical libraries or protein expression systems and should be introduced site-specifically. Herein, we probed the effect of the nPTM argpyrimidine on the structure and function of human protein Hsp27, which acquires argpyrimidine at residue 188 in vivo. We developed a synthetic approach to an argpyrimidine building block, which we then incorporated at position 188 of Hsp27 through protein semisynthesis. This modification did not affect the protein secondary structure, but perturbed the oligomeric assembly and impaired chaperone activity. Our work demonstrates that protein function can be altered by a single nPTM and opens up a new area of investigation only accessible by methods that allow site-selective protein modification.

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