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.