ISSN:
0894-3230
Keywords:
N-methyltriazolidinedione
;
biadamantylidene
;
addition reaction
;
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
---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-1 in CDCl3, ≥500 M-1 in CD2Cl2 and in the range ca 2-15 M-1 for C6D6 and C6D5Br. 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. © 1997 John Wiley & Sons, Ltd.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
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