Keteneiminium triflates

This tricky sequence was first achieved by Deyrup (75JOC2048) N-Methylation of imines with methyl triflates produces labile N-methyliminium triflates 66 and 68 in quantitative yields. Deprotonation of keteneiminium triflate 66 can be best carried out with sodium bis(trimethylsilyl)amide to... 

A similar treatment of stable keteneiminium triflate 72 with sodium bis(trimethylsilyl)amide generates azomethine ylide 73, together with a small amount of the demethylated product of 72. Ylide 73 undergoes readily dimerizes, leading to l,4-diethyl-2,5-bis[2,2-dimethyl-l-(t-butyl)propyridene]-piperazine when no dipolarophile is present. The trapping of ylide 73 with electron-deficient olefins is completely unsuccessful because these activated olefins cannot withstand such strongly basic conditions. The only dipolar-... 

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See also in sourсe #XX -- [ ]

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