3205-94-5

Valuable Diels-Alder dienophile, for example, in approach to the bicycloundecane system in taxanes.

If IR has OH peaks, then some hydrolysis to the diacid (m 178o) must have occurred. In this case reflux it with an appropriate volume of Ac2O for 30minutes, evaporate the Ac2O and distil it in vacuo. The distillate solidifies and can be recrystallised from EtOAc/hexane (1:1). The diacid distils without decomposition due to formation of the anhydride. The dimethyl ester has m 120-125o/11mm. [Askain Chem Ber 98 2322 1965, Beilstein 17/11 V 125.]