Reaction of benzoylacetaldehyde and of benzoylacetone with hydroxylamine. Acetylation of the resulting “oximes”

Abstract

Reaction of hydroxylamine with benzoylacetaldehyde gives a derivative which, in solution, is a mixture of (I; R = H), (11; R = H), and (111; R = H), whereas that from the reaction with benzoylacetone is, exclusively, (I ; R = Me) ; acetylation of the former gives (VI) and true diacetates (V; R = H), whereas that of the latter gives only true diacetates (V; R = Me).THE spectral properties of the known solid mono-oxime of benzoylacetaldehyde,l m.p. 85-7", are only interpretable by accepting that, in solution, it exists as an equiEibrium mixture of the two open oximes (11) and (111; R = H) and the "cyclo-oxime" ( I ; R = H). This is the first time we have found such an (n.m.r. observable) equilibrium mixture of open and cyclic forms in derivatives of this kind.2 Spectral properties: i.r. : 3200 (broad band; associated OH), 1672 (C=O), and 1640 cm.-l (C=N) (KBr); 3600 (free OH) and 1695 cm.-l (C=O)

A Novel Tandem [1,2]-Brook/Retro-[1,6]-Brook Rearrangement of a 1-(Trimethylsilyl)-2,4-pentadien-1-ol Anion

“…A similar 1 H NMR correlation exists with methyl ketone 13b . Isomer 13a is also inherently more stable than 14a : in methanol, 14a is completely converted to 13a in 3 h . Thermodynamic studies of the methyl ketones ( 13b, 14b ), the simplest analogues to 7 investigated in the literature, show a K eq of ≥100 in favor of 13b , or a Δ G of ≥14 kJ mol -1 .…”

“…The structure of 7 was assigned as the E -isomer based on analogy to the work of Castells, who synthesized both isomers of 3-methoxy-2-butenal ( 13a, 14a ). In the 1 H NMR of 7 , the alkene proton appears at δ 5.41, which compares more favorably to 13a (δ 5.33) than 14a (δ 5.05).…”