ADDITION OF N-METHYLTRIAZOLINEDIONE TO BIADAMANTYLIDENE

✍ Scribed by Stephen F. Nelsen; Susan J. Klein

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 78 KB
• Volume: 10
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199706)10:6<456::aid-poc908>3.0.co;2-j

✦ Synopsis

The addition of N-methyltriazolinedione (M) to biadamantylidene (A) gives the [2 + 2) adduct P, but clearly does not proceed in one step beause an aminoaziridinium intermediate (I) can be observed to build up during the reaction. The overall rate of P formation correlates with the amount of I that builds up, but not with any solvent polarity parameter, despite the fact that charge-separated intermediates are involved. NMR experiments established that the equilibrium constant for I formation is > 1000 M Ϫ 1 in CDCl 3 , ≥ 500 M Ϫ 1 in CD 2 Cl 2 and in the range ca 2-15 M Ϫ 1 for C 6 D 6 and C 6 D 5 Br. It is very unlikely that I is directly on the reaction pathway between M + A and P, and it is proposed that the zwitterionic intermediate with one CN bond, X, is the probable precursor of both I and P, although X does not build up in concentration enough to be observed. CH hydrogen bonding stabilizing both X and I in chloroform is suggested as a possible rationalization for the correlation between overall rate of P formation and stability of I relative to the starting materials. Formation of P in benzene is catalyzed by Meldrum's acid. M unfortunately reacts too rapidly with compounds containing OH bonds to study formation of P in the presence of strong hydrogen bonding reagents.