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Phosphonium-mediated synthesis of a new class of indoloquinazoline derivatives bearing C-12 aryloxy ester and spiro-γ-lactone
Indoloquinazolines functionalized at C-12 which are structure analogs of the natural alkaloid cephalanthrin B were readily constructed via a Ph3P-I2 mediated one-pot reaction of isatins with aromatic alcohols. In the presence of excess phenols, the C-12 aryloxy ester products were afforded in moderate to good yields under mild conditions. Moreover, fused bicyclic hydroxyaryl derivatives such as 8-hydroxyquinoline gave rise to novel C-12 spiro-γ-lactone derivatives. Reactive iminium cation species derived from dehydration of the C-12 hydroxy ester precursor is proposed to be transient intermediates responsible for these unprecedented transformations.
Received: 01 November 2021
Accepted after revision: 26 November 2021
26 November 2021 (online)
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