Synthesis of Enantiopure Estrone via a Double Heck Reaction

Abstract

An novel efficient catalytic approach to steroids by a double Heck reaction of the vinyl bromides 2 and the CD-building block 3 is presented. The new estrogen analogues 1a and 1b are formed via 23a and 23b in a highly regio- and stereoselective manner in good yields. They contain a cis -BC ring junction and two double bonds in the 6,7- and the 11,12-positions which can be functionalized in a selective way. Inter alia, homogeneous hydrogenation with (PPh 3 ) 3 RhCl to give 28 followed by hydrogenation with 1,4-cyclohexadiene in the presence of palladium affords the known estradiol derivative 29a in 76% yield which can easily be transformed into estrone 31 .