Structure of trimethylsilyl derivatives of acetic acid hydrazides

Silylation of N,O-Diacylhydroxylamines: NMR Spectra and Structure of the Products

“…h Coupling to the CH3 acetyl proton 3 J( 15 N-1 H) ) 3.1 Hz. formation of Si-O products was reported for the structurally close N′,N′-dimethylhydrazides of carboxylic acids [20][21][22] and proved for the silylation of hydroxamic acids, 14,23,24 in contrast to the originally proposed structure. 15,25 The E/Z ratios of O-silylated isomers, i.e., 7:8, found here can be compared to those established in silylated hydroxamic acids and N′,N′-dimethylhydrazides, which are controlled in a similar way.…”

“…The E/Z ratios of O-silylated isomers, i.e., 7 : 8 , found here can be compared to those established in silylated hydroxamic acids and N ‘ ,N ‘ -dimethylhydrazides, which are controlled in a similar way. Ring-substituted benzhydroxamic acids produced solely Z isomers of disilyl derivatives, ,, while the aliphatic hydroxamic acids yielded mixtures of E and Z isomers. , Trimethylsilylation of aromatic N ‘ ,N ‘ - dimethylhydrazides also leads only to the Z isomers, while in the case of the aliphatic derivative the E isomer is formed as well. − …”

“…14,27 Trimethylsilylation of aromatic N′,N′-dimethylhydrazides also leads only to the Z isomers, while in the case of the aliphatic derivative the E isomer is formed as well. [20][21][22] Calculated Structures and Energies. The absence of N-silyl derivatives among our products may have both kinetic and thermodynamic origins: i.e., the low nucleophilicity of nitrogen or subsequent equilibration.…”

“…1 H NMR (CDCl3): 0.39 (s, 6H, CH3Si), 0.98 (s, 9H, CH3-CSi), 2.12 (s, 3H, CH3CdN), 7.46 (m, 2H, H-3/5), 7.57 (m, 1H, H-4), 8.05 (dd, 2H, H-2/6). MS (EI; m/z (%)): 236 (22) [M -C4H9 + ]; 179 (31); 135 (10); 105 (100).…”

The Chemistry of Hydrazonates

“…Likewise, Shawali et al [12,13] reported that aryl alkanehydrazonates undergo similar base catalyzed rearrangement when refluxed in ethanol in the presence of triethylamine. Trimethylsilyl N,N-disubstituted ethanehydrazonate was reported to exist in equilibrium with the hydrazide 128 [78,79].…”