Synthesis and Structure of Condensed Heterocycles Derived from Intramolecular 1,3-Dipolar Cycloaddition of Transient and Enantiomerically Pure α-Allylamino Nitrones and Nitrile Oxides in a High Level of Diastereoselectivity
absolute stereochemistry of the products were confirmed by extensive 2D-NMR spectroscopy and single crystal X-ray analyses and the reasons for the observed selectivity were explained by the energy calculations of the transition states using semiempirical (MOPAC AM1 and MOPAC PM3) and abinitio methods (3-21G* and 6-31G*).
Halogenovinyl Sulfones. 6.<sup>1</sup> Synthesis of Condensed Heterocycles by Diastereoselective Intramolecular Diels−Alder Reactions of Sulfonyl-Substituted Trienes
Sulfonyl trienes having a chiral center on the allyl carbon of the diene moiety were prepared from L-amino acid as chiral building blocks. Intramolecular Diels-Alderreaction of the sulfonyl trienes having E-geometry on the diene moiety proceeded on the si-face and exo-selectively to give cis-isoindoles as a sole product in good yields. But using the sulfonyl trienes having Z-geometry on the diene