General Approach to 2,3-Dibenzyl-γ-butyrolactone Lignans: Application to the Total Synthesis of (±)-5′-Methoxyyatein, (±)-5′-Methoxyclusin, and (±)-4′-Hydroxycubebinone

The total synthesis of natural lignans 5′‐methoxyyatein (1), 5′‐methoxyclusin (2), and 4′‐hydroxycubebinone (3), in racemic form, has been achieved by a newly developed strategy, wherein lithium naphthalenide induced decyanation was employed as a key operation to establish the essential trans configuration of the butyrolactone ring. A concise synthetic route to the 2,3‐dibenzylbutyrolactone core has been developed, whereby the total synthesis of natural lignans 1, 2, and 3, in racemic form, in an overall yield of 25, 18, and 19 %, respectively, has been accomplished.