General synthesis of highly functionalized cyclopentane segments for the preparation of jatrophane diterpenes.

Short and efficient syntheses of two diastereomeric cyclopentane segments present in most jatrophane diterpenes were achieved. Key steps are a stereoselective C-2 elongation, an RCM, and a hydroboration reaction. An orthogonal protecting group methodology makes these segments useful building blocks for diterpene synthesis.