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
✍ Scribed by Adam, Waldemar ;Grabowski, Sven ;Hinz, Ricardo F. ;Lucchini, Vittorio ;Peters, Eva-Maria ;Peters, Karl ;Rebollo, Hector ;von Schnering, Hans Georg
- Book ID
- 102787656
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1987
- Tongue
- English
- Weight
- 550 KB
- Volume
- 120
- Category
- Article
- ISSN
- 0009-2940
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✦ Synopsis
4-Phenyl-l.2,4-triazolinc-3.5-dione (PTAD) or 4-mcthyl-l.2.4-triazolinc-3,5-dione (MTAD) cycloaddition to the 7-cyclohcptatrienecarboxylates gave the endo-urazolcs I . With the 7.7-cyclohcptatrienedicarboxylatcs 5 the urazoles 6 were formed. Dccarboxylation of urazole 6 c led to c,rtdo-l b, showing that steric factors prevcnt formation of the desired exo-1 b isomer. Attempts to isornerize undo-l b and rndo-1 c by base catalysis, afforded after methylation with mcthyl iodide the 2,4-dioxohcxahydro-1,3,5-triazine derivativcs 2a,b. This unusual rcarrangcmcnt also took placc with urazolc 3 leading to 1,3.5-triazine 4. but the urazolcs derived from butadicne and cyclopntadiene did not respond. ' H NMR diffcrentid NOE and X-ray analysis of 2b and 6c were necessary for the structural elucid:rtion of the 1.3.5-triazines 2a, b.