Terpenes have a large variety of carbon skeletons characterized by branched chains, and often complex multicyclic ring systems. They are oligomers of the biological isoprene unit, which is a relativel...Terpenes have a large variety of carbon skeletons characterized by branched chains, and often complex multicyclic ring systems. They are oligomers of the biological isoprene unit, which is a relatively reduced hydrocarbon comprised of five carbons. It is produced in nature from three molecules of a relatively oxidized two carbon starting material, acetic acid in the form of acetyl CoA.
Thus, dislocation of the monocyclic target to a bicyclic target recognizes the potential of retroaldol cleavage of a cyclobutane ring for generation of the required vicinal cis relationship of the mal...Thus, dislocation of the monocyclic target to a bicyclic target recognizes the potential of retroaldol cleavage of a cyclobutane ring for generation of the required vicinal cis relationship of the malonyl and carboxaldehyde substituents of the target. Since this involves stereospecific addition of the borane to the least hindered face of 18, the configuration at the carbinol carbon had to be inverted during the preparation of the acetate 19.
