O'Reilly RJ, Radom L. Ab initio investigation of the fragmentation of 5,5-diamino-substituted 1,4,2-oxathiazoles.
Org Lett 2009;
11:1325-8. [PMID:
19245242 DOI:
10.1021/ol900109b]
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Abstract
The mechanism for the fragmentation of 5,5-diamino-1,4,2-oxathiazole derivatives has been studied at the CCSD(T)/6-311+G(3df,2p)//MP2/6-31+G(2df,p) level of theory. The calculations suggest that the fragmentation occurs via a stepwise process involving the formation of polar intermediates that lie in shallow potential wells. We find a large thermodynamic driving force for fragmentation, which together with a weakening of the C-S bond through electron donation by the amino substituents provides the impetus for a low-barrier fragmentation.
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