Diastereoselective Synthesis of an Isoprostane:<b> (</b>±)-8-<i>epi</i>-PGF₂_α Ethyl Ester

A total synthesis of the isoprostane (±)-8-<i>epi</i>-PGF₂_α ethyl ester (<b>5</b>) is described, based on the diastereoselective cyclization of α-diazo ketone <b>7</b>. This ketone is assembled by aldol condensation between α-diazo ketone <b>8</b> and aldehyde <b>9</b>. The sequential α-diazo ketone aldol/insertion described here offers a powerful new approach to cycloalkane construction.