Use of RCM Reactions for Construction of Eight-Membered Carbocycles and Introduction of a Hydroxy Group at the Juncture between Five- and Eight-Membered Carbocycles

Model studies for total synthesis of YW3699 were carried out in order to introduce a hydroxy group at the ring juncture between 5- and 8-membered carbocycles. The five-membered ring part hydrazone and aldehyde with a cyclohexane ring were connected by the Shapiro reaction followed by conversion to diketones which were treated with IBX to afford hydroxylated models.

Construction of eight-membered carbocycles with trisubstituted double bonds using the ring closing metathesis reaction

Medium sized carbocycles are particularly difficult to synthesize. Ring closing metathesis reactions (RCM) have recently been applied to construct eight-membered carbocycles, but trisubstituted double bonds in the eight-membered rings are more difficult to produce using RCM reactions. In this review, model examples and our own results are cited and the importance of the preparation of suitably designed precursors is discussed. Examples of RCM reactions used in the total synthesis of natural products are also outlined.