A Total Synthesis of Galbonolide B

An ester enolate rearrangement/silicon mediated fragmentation cascade was used to convert <b>7</b> and <b>8</b> into the alcohol <b>9</b>. The alcohol <b>9</b> was converted into the allylic alcohol <b>12</b> and then to the ester <b>14</b>. A further ester enolate rearrangement furnished the stereochemical identity of galbonolide B <b>1</b>. Base mediated macrocyclization of the acetate ester <b>16</b> followed by base mediated alkylation and acetal deprotection gave galbonolide B <b>1</b>.