We have combined the biocatalytic desymmetrization of 3,4-cis-substituted meso-pyrrolidines with an Ugi-type multicomponent reaction followed in situ by a Pictet-Spengler-type cyclization reaction sequence for the rapid asymmetric synthesis of alkaloid-like polycyclic compounds.
Abstract. Copper undecaarylcorroles were found to undergo acid-induced demetalation with unusual ease under both reductive and nonreductive conditions. The resulting free-base undecaarylcorroles were found to be rather reactive, readily photooxygenating to yield 5/10-hydroxyisocorroles and biliverdines. The use of nonreductive conditions led to fairly good yields of undecaarylisocorroles, a new class of sterically hindered ligands, of which one proved amenable to single-crystal X-ray structural analysis. In one case, interaction of an undecaarylisocorrole with gold(III) acetate resulted in aromatization of the macrocycle and a gold undecaarylcorrole. The Au complex exhibited Au-N distances of 1.941(3)-1.965(3) Å, and no significant nonbonded interactions involving the gold. The significant solubility of this complex in organic solvents, compared with the relative insolubility of gold -octabromo-mesotriarylcorroles, appears to be related to the lack of aurophilic and metallophilic interactions.2
3,4-cis-substituted imines, such as (I), prepared via biocatalytic desymmetrization as reported earlier, are used as imine components in an Ugi-type multicomponent reaction. The products (IV) obtained are further subjected to a Pictet-Spengler-type cyclization to assemble alkaloid-like polycyclic compounds, e.g. (V), (VI), (VII), and (IX). -(ZNABET, A.; ZONNEVELD, J.; JANSSEN, E.; DE KANTER, F. J. J.; HELLIWELL, M.; TURNER, N. J.; RUIJTER*, E.; ORRU, R. V. A.; Chem. Commun. (Cambridge) 46 (2010) 41, 7706-7708, http://dx.doi.org/10.1039/c0cc02938f ; Dep. Chem. Pharm. Sci., Vrije Univ., NL-1081 HV Amsterdam, Neth.; Eng.) -M. Paetzel
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