Cascade Reactions. A Simple One-pot Synthesis of the Mitomycin Skeleton
作者:Albert Defoin、Guillaume Geffroy、Didier Le Nouen、Didier Spileers、Jacques Streith
DOI:10.1002/hlca.19890720604
日期:1989.9.20
types of cascade reactions which give pyridinium betaines 6 and pyrrolo-indoles 8 as the major reaction products. The one-pot syntheses of pyrroloindoles 8 represent a new and easy access to the basicskeleton of mitomycins 10. The scope and limitations of the cascade reactions were investigated.
Reaction of [E,E]-hexa-2,4-dienal with nitrosobenzene led regiospecifically to the Diels-Alder cycloadduct which is unstable at room temperature. Its enol form underwent a hetero-Cope rearrangement, giving ultimately the pyrroloindole . Simultaneously base-catalyzed deprotonation of gave the dicarbonyl intermediate which ring-closes in two ways, leading eventually to the betaïne and to small amounts
An unusual furan cycloadduct from N-phenylbetaine and dimethyl acetylenedicarboxylate. The crystal and molecular structure of dimethyl 5-(3-N-phenyliminoprop-1-enyl)furan-2,3-dicarboxylate
作者:George Ferguson、Keith J. Fisher、Badr Eldin Ibrahim、Christina Y. Ishag、George M. Iskander、Alan R. Katritzky、Masood Parvez
DOI:10.1039/c39830001216
日期:——
Cycloaddition of dimethylacetylenedicarboxylate with betaines such as 1-phenyl-3-oxidopyridinium does not yield the expected bicyclic product; instead, addition occurs at the exocyclic oxygen atom and ring carbon 2 of the betaine, with concomitant opening of the pyridine ring.
Analysis of the products formed by the addition of N-phenylpyridium betaines to someunsymmetricalalkenes revealed that the 2-methyl-or-mehtyl-or 2-phenyl-N-phenylpyridinium betaine tends to form the reverseorientation products, whereas the unsubstituted N-phenylpyridium betaine gives the expected orientation.