Stereochemical assignment of the unique electron acceptor 5'-hydroxyphylloquinone, a polar analog of vitamin K 1 in photosystem I.

A unique electron-accepting analog of vitamin K ₁ found in photosystem I in several species of oxygenic photosynthetic microorganisms was confirmed to be 5'-hydroxyphylloquinone (1) through stereo-uncontrolled synthesis. Furthermore, the stereochemistry of 1 obtained from Synechococcus sp. PCC 7942 was assigned to be 5'S using proline-catalyzed stereocontrolled reactions.