Total synthesis of nepodin and torachrysone glucosides: Evidence for naturally occurring l-glucosides

The first concise synthesis of nepodin-1-O-β-d-glucopyranoside (D-1) and its l-glucopyranoside (L-1), as well as torachrysone-1-O-β-d-glucopyranoside (D-2) and its l-glucopyranoside (L-2), was achieved via Fries rearrangement and selective glycosylation. Spectral data, particularly the specific rotation signs of the synthetic l-glucosides, correlated with those of natural products previously isolated from Rumex dentatus. This confirms the presence of naturally occurring l-glucosides, L-1 and L-2, identified through synthetic approaches.