SynBio-SynChem approaches to diversifying the pacidamycins through the exploitation of an observed Pictet-Spengler reaction

A nonenzymatic Pictet‐Spengler reaction has been postulated to give rise to a subset of naturally occurring uridyl peptide antibiotics (UPAs). Here, using a combination of strain engineering and synthetic chemistry, we demonstrate that Pictet‐Spengler chemistry may be employed to generate even greater diversity in the UPAs. We use an engineered strain to afford access to meta‐tyrosine containing pacidamycin 4. Pictet‐Spengler diversification of this compound using a small series of aryl‐aldehydes was achieved with some derivatives affording remarkable diastereomeric control.