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Acetylenic amides. 2 . The generation and reactions of dianions derived from 2‐propynamides
Author(s) -
Coppola Gary M.,
Damon Robert E.
Publication year - 1995
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570320406
Subject(s) - chemistry , yield (engineering) , carboxylation , trimethylsilyl , carbon dioxide , medicinal chemistry , organic chemistry , dimethyl sulfoxide , benzyl bromide , carbon fibers , bromide , catalysis , materials science , composite number , metallurgy , composite material
The dianion of N ‐benzyl‐2‐propynamide can be generated by the treatment of 4 with two equivalents of LDA at −65° or ethylmagnesium bromide at −20°. 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 chlorotrimethylsilane produces N ‐benzyl‐3‐trimethylsilyl‐2‐propynamide ( 13 ) in high yield. Reduction of 9 furnishes either fully saturated amides 15 or partially reduced cis ‐olefins 16 or 18 . Compounds 16 , on heating, rearrange to 4‐ketoamides 17 . Carboxylation of 5a with carbon dioxide produces 3‐benzyl‐2,4‐dioxo‐5‐oxazidinylacetic acid ( 11 ). Warming 11 in dimethyl sulfoxide results in the loss of carbon dioxide and the formation of N ‐benzylpyruvamide ( 21 ).