A partial synthesis of (-)-shinjulactone H (3) from (+)-quasin (1) required the selective manipulation of two similar 0-methyldiosphenol groups. Protection of the &lactone in 1 as an ortho ester, selective reduction of the C-1 carbonyl group, hydrolysis of the resulting enol ether in the A ring, and catalytic hydrogenation of the 0-methyldiosphenol in the C ring delivered an intermediate possessing an a-keto1 group in the A ring and an a-methoxy ...