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Synthesis and Transformations of Urazoles Derived from 7,7‐Dicarboxynorcaradiene: Formation of 2,4‐Dioxohexahydro‐1,3,5‐Triazines by an Unusual Base‐Catalyzed Rearrangement
Author(s) -
Adam Waldemar,
Grabowski Sven,
Hinz Ricardo F.,
Lucchini Vittorio,
Peters EvaMaria,
Peters Karl,
Rebollo Hector,
von Schnering Hans Georg
Publication year - 1987
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19871201219
Subject(s) - chemistry , cycloaddition , methyl iodide , decarboxylation , cyclopentadiene , catalysis , stereochemistry , iodide , base (topology) , triazine , medicinal chemistry , cope rearrangement , organic chemistry , mathematical analysis , mathematics
4‐Phenyl‐1,2,4‐triazoline‐3,5‐dione (PTAD) or 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (MTAD) cycloaddition to the 7‐cycloheptatrienecarboxylates gave the endo ‐urazoles 1 . With the 7,7‐cycloheptatrienedicarboxylates 5 the urazoles 6 were formed. Decarboxylation of urazole 6c led to endo ‐ 1b isomer. Attempts to isomerize endo ‐ 1b and endo ‐ 1c by base catalysis, afforded after methylation with methyl iodide the 2,4‐dioxohexahydro‐1,3,5‐triazine derivatives 2a, b . This unusual rearrangement also took place with urazole 3 leading to 1,3,5‐triazine 4 , but the urazoles derived from butadiene and cyclopentadiene did not respond 1 H NMR differential NOE and X‐ray analysis of 2b and 6c were necessary for the structural elucidation of the 1,3,5‐triazines 2a, b .