Stereochemistry Part 1 Solutions: #1

1.* (1997 F 6) Taxol is an exciting anticancer agent for the treatment of advanced ovarian and breast cancer. Taxol is derived from the bark of the yew tree (which kills the tree) and by chemical modification of more readily available natural product from the needles of the yew. The structure of taxol is shown below.

A. Place an asterisk beside each chiral carbon in taxol.

B. What is the absolute configuration of the rightmost carbon attached to an OH (labelled with an arrow in the figure).

S. The lowest priority substituent (H) is already convieniently pointing back into the page. The highest priority substituent is the OH, second highest is the group to the right (because of the double bond to O), and third highest is the group to the left. Thereforer the priorities are arranged in a counterclockwise fashion. This is S.

C. How many sites of unsaturation are in taxol?