Stereocontrolled asymmetric synthesis*

Abstract: Stereo differentiated asymmetric syntheses have been achieved by S-indoline deri-vations. Diels–Alder cycloadditions of S-indoline chiral acrylamides with cyclopentadiene proceed with high diastereofacial selectivity, giving either endo-R or endo-S products depending on Lewis acid and the structures of chiral dienophiles. Diastereo- and enantio-selective pinacol coupling reactions of chiral α-ketoamides mediated by samarium diiodide afforded extremely high diastereoselectivities. Enantiopure (S,S)- or (R,R)-2,3-dialkyltar-taric acid and derivatives can be synthesized for the first time depending on the structure of α-ketoamides. Lewis acid-catalyzed addition of dienes to chiral acrylamides is a useful reaction because it provides one of the most effective methods for creating new chiral centers during the formation of six-membered rings [1]. Lewis acids have been used for chelate formation in Diels–Alder cyclizations to obtain high diastereofacial selectivities [1–5]. In general, the S-form of the chiral dienophile (auxiliary) exclusive-ly affords the endo-R adduct over the endo-S one, and the R form exclusively gives the S adduct over the endo-R one. Issues associated with this absolute stereochemical control depending upon Lewis acids and the structures of dienophiles provide an important challenge in the area of practical Diels–Alde