Stereochemical assignment of the unique electron acceptor 5′-hydroxyphylloquinone, a polar analog of vitamin K₁ in photosystem I

Figures & data

Fig. 1. 600 MHz ¹H NMR spectrum of as-synthesized 5′-hydroxyphylloquinone (1) determined in CDCl₃ using a JEOL ECA-600.

Fig. 2. Chiral GLC charts of stereocontrolled and uncontrolled products 4 derived from industrial VK₁. (a) (4S)-enriched 4 derived from l-proline-catalyzed reaction, (b) (4R)-enriched 4 derived from d-proline-catalyzed reaction, (c) (4RS)-4 derived from VK₁, and (d) stereoisomeric mixture of 4 prepared in Scheme 3.

Fig. 3. TIC and mass chromatogram charts of compound 4 derived from natural 1 and stereo-controlled synthetic products 4 derived from industrial VK₁. The TIC chart for (a) 4 derived from the natural product. Mass cromatograms at m/z 283 for 4 derived from the (b) natural product, (c) synthetic (4S)-4, (d) synthetic (4R)-4 and (e) synthetic (4RS)-4. The chart of (a) was integrated three times (n = 3) and smoothed using a seven-point weighted moving average.

Scheme 1. Retrosynthesis of 5′-hydroxyphylloquinone (1).

Scheme 2. Preliminary process for the five-carbon-unit extension.

Scheme 3. Preparation of the hydrocarbon chain component.

Scheme 4. Structure of the Friedel–Crafts adduct 11 and its derivative 12.

Scheme 5. Structural determination and asymmetric synthesis of 4.