Ketimines From Ketones and Ammonia

The First Acetimine Gold(I) and Gold(III) Complexes and the First Acetonine Complexes

“…[3] Unlike N-substituted imines, the unsubstituted NH-aldimines, HN CHR, or NH-ketimines, HNCRR', are, with the exception of diarylketimines, unstable compounds that need to be trapped with various reagents. [2] In particular, HNCMe 2 (acetimine) can be prepared from acetone and ammonia, but requires an ammonium chloride-catalyzed reaction at 50 bar and 120 8C [4] or the use of zeolite HZSM-5 over 250 8C. [5] Although it is stable at 0 8C for short periods of time it decomposes on storage to give 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine (acetonine; see Scheme 1).…”

“…The formation of acetimine from acetone and ammonia. Conditions: either a) NH 4 Cl catalyst, 50 bar, 120 8C; or b) zeolite HZSM-5 catalyst, 250 8C. Acetimine is stable for short periods at 0 8C, but eventually decomposes to give acetonine.…”

“…It has been reported to form among the decomposition products of acetimine (NH CMe 2 ) [6] but it is best obtained from the reaction of acetone with ammonia, and many attempts are currently reported, most of them patents, to improve its synthesis. Thermal [25] or photochemical [26] activation as well as a wide variety of catalysts including Mg/Al complexes, [27] Fe carboxylates, [28] halo complexes of B, Al, Si, P, As, Ti, Pd, Pt, [29] zeolites, [30] NH 4 Cl, [31] or p-nitro-calix [4]arene [32] have been used to that purpose. Acetonine finds its main use in its reaction with acetone to give triacetonamine (2,2,6,6-tetramethyl-4-oxopiperidine).…”

The crystal structure of Afc-containing peptides

“…18 -20,23,37,38 The crystal structures of four peptides Z-Gly A solution of N-Z-amino acid (Z-AA 1 ; 11 mmol), 9-fluorenonimine (1.97 g, 11 mmol), prepared according to Verardo, 39 and methyl isocyanoacetate or methyl 2-isocyano-2-methylpropionate (10 mmol) in CH 2 Cl 2 (12 mL), was stirred at room temperature for 12 or 14 days. The solvent was removed under vacuum, and the residue was dissolved in CHCl 3 (60 mL).…”

Benzophenone Imine

“…1 It is a commercially available liquid which is easily prepared by addition of phenylmagnesium bromide to benzonitrile followed by hydrolysis with methanol 2 or by reaction of benzophenone with ammonia. 3 Synthetic applications of 1 have been historically related to peptide chemistry, specifically as protecting group of primary amines during the preparation of optically active a-amino acids. 4 Used in conjunction with other anionstabilising groups, 1 provides activation for proton abstraction.…”