A direct and efficient stereocontrolled synthetic route to the pseudopterosins, potent marine antiinflammatory agents

Described herein is a new synthetic route to pseudopterosin aglycone (3), a key intermediate for the synthesis of a group of antiinflammatory natural products including pseudopterosin A (1) and E (2). The pathway of synthesis starts with the abundant and inexpensive (S)-(-)-limonene and its long-kno wn cyclic hydroboration product (4) and leads to the chiral hydroxy ketone 6. Conversion of 6 to 10 followed by a novel aromatic annulation produced 1 5 which underwent a highly diastereoselective cyclization to afford the pro tected pseudopterosin aglycone 16. The naturally occurring pseudopterosins such as 1 and 2 are readily available from this key intermediate.