Finally, further catalytic enamine activation initiates an intramolecular aldol condensation to close the six-membered ring.

Sorbiterrin A is a newly discovered member of the sorbicillin family of polyketides in which the unusual [3.3.1] ring system was proposed to be generated via an intramolecular aldol/dehydration ...

The fatty acid ester was nonenzymatically converted to a butenolide phosphate by intramolecular aldol condensation. The butenolide phosphate was then reduced by BprA that was encoded just downstream ...