ACETYLENIC AMIDES .2. THE GENERATION AND REACTIONS OF DIANIONS DERIVED FROM 2-PROPYNAMIDES

The dianion of N-benzyl-2-propynamide can be generated by the treatmen t of 4 with two equivalents of LDA at -65 degrees or ethylmagnesium br omide at -20 degrees. The trilithio species 6 is readily formed using 3 equivalents of LDA. Reaction of 5 with aldehydes or ketones produce hydroxypropynamides 9 in good yields. Silation of 5a with chlorotrimet hylsilane produces N-benzyl-3-trimethylsilyl-2-propynamide (13) in hig h yield. Reduction of 9 furnishes either fully saturated amides 15 or partially reduced cis-olefins 16 or 18. Compounds 16, on heating, rear range to 4-ketoamides 17. Carboxylation of 5a with carbon dioxide prod uces 3-benzyl-2,4-dioxo-5-oxazidinylacetic acid (11). Warming 11 in di methyl sulfoxide results in the loss of carbon dioxide and the formati on of N-benzylpyruvamide (21).