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4-Methylpyrimidinium Ylides II: Selective Reactions of Pyrimidinium Ylides with Activated Alkynes
31 December 2000 (online)
The reaction of 4-methylpyrimidinium ylides (as 1,3-dipoles) with DMAD (dimethyl acetylenedicarboxylate) and DFA (diphenylacetylene) as dipolarophiles is presented. 4-Methylpyrimidinium ylides did not react with DFA. A selective route to obtain new azabicyclic structures derived from pyrimidine via the reaction of pyrimidinium ylides with DMAD is also presented. In addition to the azabicyclic compounds, an unexpected betaine structure has been obtained, and a possible mechanism for the reaction pathway is proposed. A selective way to increase the proportion of azabicyclic compound or betaine was determined.
nitrogen ylides - alkynes - cycloadditions - selective synthesis - pyrimidine