Taxol (compound 3) can be isolated from the bark of the Pacific yew tree, Taxus

Chapter 9, Problem 9.84

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Taxol (compound 3) can be isolated from the bark of the Pacific yew tree, Taxus brevifolia, and is currently used in the treatment of several kinds of cancer, including breast cancer. Each yew tree contains a very small quantity of the precious compound (approximately 300 mg), enough for just one dose for one person. This fueled great interest in a synthetic route to taxol, and indeed, several total syntheses have been reported. During K. C. Nicolaous classic synthesis of taxol, compound 1 was treated with BH3 in THF, followed by oxidative workup, to afford alcohol 2. The formation of 2 is observed to occur regioselectively as well as stereoselectively (Nature 1994, 367, 630634): O O O O O O O O O H 1 2 2) H2O2, mild base O OH O OH O O H 3 O O O O O O N H OH O 1) BH3 THF (a) Identify the functional group in 1 that will react with BH3 and justify your choice. (b) Predict the regiochemical and stereochemical outcome of the process and draw the structure of compound 2.