Rearrangements from the 2-Hydroxyl Group

In the first experiment using racemic l,2-[2-l80]propanediol a 43% retention of 180 was observed in the propanol. This important result demonstrates that a 1,2-migration of the secondary hydroxyl group to C-l does indeed occur during the rearrangement, and an explanation for the loss of almost 50% of the label, when using a racemic substrate, was also forthcoming from two subsequent experiments. 

Under oxidizing conditions (Jones reagent), taxol is converted to the 7-keto derivatives 20a and 20b (43) (see Scheme 3). Under these same conditions (2,11,28), the free 13-hydroxyl group of baccatin III (13b) and 10-deacetyl baccatin III (13a) is oxidized to form 13-oxobaccatin III (21b) and the deacetyl derivative (21a), respectively. Treatment of compound 20c, derived from the oxidation product 20a after protection of its 2 -hydroxyl group, with base leads to rearrangement products such as D-seco taxane 22. 

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