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Stereoelectronic Effects in the Iodine‐Promoted Oxidation of Pentacyclic Tetrahydroisoquinolines
Author(s) -
Koepler Oliver,
Laschat Sabine,
Miehlich Burkhard,
Baro Angelika,
Fischer Peter
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490173
Subject(s) - chemistry , iminium , diastereomer , moiety , aminal , intramolecular force , stereochemistry , tetrahydroisoquinoline , medicinal chemistry , ion , organic chemistry
Iodine‐promoted oxidations of the pentacyclic tetrahydroisoquinolines 4a, 4b , and 10 were investigated. Whereas the all‐ cis diastereoisomer 4a containing an arylamino moiety gave the iminium ion 5 as the primary product, which subsequently underwent intramolecular aminal formation to 6 , the corresponding all‐ trans diastereoisomer 4b epimerized to the all‐ cis diastereoisomer 4a via iminium ion 7 . In contrast, tetrahydroisoquinoline 10 could be cleanly oxidized to the corresponding isoquinolizidinium ion 11 . Mechanistic considerations were supported by molecular‐modeling calculations.