Abstract
The first total synthesis of the 9,10-seco-kaurene velloziolone (3) has been accomplished using an atom transfer
tandem free-radical cyclization to prepare the 6-methylenebicyclo[3.2.1 ]octan-2-one moiety. The known diol 11 is converted to iodo acetate 10 in three steps. Alkylation of d-keto ester 22 with 10 affords 33 that is converted
to -iodo ketone 7 in one pot by silylation, followed by palladium-catalyzed decarboxylation to give the tetra- substituted silyl enol ether regiospecifically and iodination of the enol ether. Atom transfer cyclization at 150 °C, but not at 25 or 85 °C, provides a mixture of bicyclic iodides. Elimination of HI and hydrolysis of the acetate furnishes velloziolone.