| We have investigated the use of ketal as a tether in RCM reaction to demonstrate a conceptually different synthesis of spiroketals or spiroaminals. In our pursuit of cyclic ketal- or aminal tethered RCM reactions, we encountered new possible mode of stereochemical control in anomeric substitutions to synthesize cyclic aminals. We rationalized the origin of the observed stereochemical outcome by mechanistic and computational study.;We explored Lewis acid-catalyzed intramolecular Gassman's [2+2] cycloaddition. We optimized the reaction conditions for the cycloaddition and established the substrate scope. To apply this methodology, we pursued the formal syntheses of raikovenal and epiraikovenal.;We have developed a novel approach to cyclic aminals by a stereoselective haloetherification of chiral enamides. The potential of this methodology was described by the sequential N-alkenylation via amidative cross-coupling/haloetherification toward synthetically challenging chiral secondary halide. |
