Nucleophilic Addition of Organozinc Reagents to 2-Sulfonyl Cyclic Ethers: Stereoselective Synthesis of Manassantins A and B

A convergent route to the synthesis of manassantins A and B, potent Inhibitors of HIF-1, is described. Central to the synthesis is a stereoselective addition of an organozinc reagent to a 2-benzenesulfonyl cyclic ether to achieve the 2,3-cis-3,4-trans-4,5-cis-tetrahydrofuran of the natural products. Preliminary structure-activity relationships suggested that the (R)-configuration at C-7 and C-7''' is not critical for HIF-1 inhibition. In addition, the hydroxyl group at C-7 and C-7''' can be replaced with a carbonyl group without loss of activity.