1193-17-5Relevant academic research and scientific papers
Air Stable Iridium Catalysts for Direct Reductive Amination of Ketones
Polishchuk, Iuliia,Sklyaruk, Jan,Lebedev, Yury,Rueping, Magnus
, p. 5919 - 5922 (2021)
Half-sandwich iridium complexes bearing bidentate urea-phosphorus ligands were found to catalyze the direct reductive amination of aromatic and aliphatic ketones under mild conditions at 0.5 mol % loading with high selectivity towards primary amines. One of the complexes was found to be active in both the Leuckart–Wallach (NH4CO2H) type reaction as well as in the hydrogenative (H2/NH4AcO) reductive amination. The protocol with ammonium formate does not require an inert atmosphere, dry solvents, as well as additives and in contrast to previous reports takes place in hexafluoroisopropanol (HFIP) instead of methanol. Applying NH4CO2D or D2 resulted in a high degree of deuterium incorporation into the primary amine α-position.
Ni-Catalyzed reductive amination of phenols with ammonia or amines into cyclohexylamines
Cuypers, Thomas,Morias, Thomas,Windels, Simon,Marquez, Carlos,Van Goethem, Cédric,Vankelecom, Ivo,De Vos, Dirk E.
, p. 1884 - 1893 (2020/04/07)
Phenol and its derivatives, which naturally occur in lignocellulose, can be considered as a renewable feedstock not only for aromatic, but also for alicyclic compounds, such as primary and N-substituted cyclohexylamines. So far, the latter are mostly produced from non-renewable starting materials like benzene via problematic nitration/reduction or cross-coupling routes. Herein, an efficient reductive amination of phenol with ammonia or amines is demonstrated, for the first time without the need for rare and expensive noble metals and without using any additives. Various supported Ni catalysts were screened and we elucidated the influence of the key parameters, including the acid-base properties of the supporting material. Acquired knowledge was then applied to different phenol-ammonia/amine combinations, resulting in the synthesis of various primary, secondary and tertiary cyclohexylamines in fair to very high yields.
The Rhodium Catalysed Direct Conversion of Phenols to Primary Cyclohexylamines
Tomkins, Patrick,Valgaeren, Carlot,Adriaensen, Koen,Cuypers, Thomas,Vos, Dirk E. De
, p. 3689 - 3693 (2018/07/31)
Cyclohexylamines are important intermediates in chemical industry, which are currently produced from petrochemical sources. Phenols, however, are an attractive sustainable feedstock. We here demonstrate the transformation of phenols with ammonia to primary cyclohexylamines. In contrast to previously reported chemistry which used palladium catalysts, we here show that rhodium is an excellent catalyst for the formation of primary cyclohexylamines. Different parameters were studied and it was shown that the reaction is applicable to a scope of phenolic compounds providing high selectivity.
Enhanced Selectivity in the Hydrogenation of Anilines to Cyclo-aliphatic Primary Amines over Lithium-Modified Ru/CNT Catalysts
Tomkins, Patrick,Müller, Thomas E.
, p. 1438 - 1445 (2018/03/30)
The hydrogenation of aromatic amines to the corresponding cycloaliphatic primary amines is an important industrial reaction. However, secondary amine formation and other side reactions are frequently observed, resulting in reduced selectivity. The side products are formed mostly on the support, yet support effects are little understood at present. This study describes the facile modification of Ru/CNT catalysts with LiOH, by this means significantly improving catalyst selectivity in toluidine hydrogenation without decreasing the activity of the catalysts. The effect is explained by LiOH diminishing acidic sites on the catalyst support and enhancing the adsorption of the aromatic ring on the metallic ruthenium nanoparticles. With the LiOH-modified Ru/CNT catalyst, other substrates, such as methylnitrobenzenes, are also converted efficiently. This study thus describes an improved catalyst for the preparation of cyclohexylamines and provides guidelines for future catalyst design.
HIGHLY STEREOSELECTIVE SYNTHESIS OF CYCLIC PRIMARY AMINES VIA HYDRIDE REDUCTIONS.
Hutchins, Robert O.,Su, Wei-Yang
, p. 695 - 698 (2007/10/02)
The reduction of p,p'-dimethoxybenzhydryl imines of substituted cyclohexanones with lithium tri-sec-butyl or tri-ethylborohydride and subsequent cleavage of the resulting secondary amines with formic acid affords the corresponding axial cyclohexyl primary amines with high stereoselectivity.
Synthesis of analogues of N (2 chloroethyl) N' trans 4 methylcyclohexyl) N nitrosourea for evaluation as anticancer agents
Johnston,McCaleb,Clayton,Frye,Krauth,Montgomery
, p. 279 - 290 (2007/10/04)
The superior activity of N (2 chloroethyl) N' (trans 4 methylcyclohexyl) N nitrosourea (MeCCNU) against advanced murine Lewis lung carcinoma in comparisons with the cis form and other nitrosoureas prompted the synthesis of a number of MeCCNU analogues, including several cis trans pairs. The methyl group was replaced by a variety of substituents (CO2H, CH2CO2H, CO2Me, CH2OAc, CH2Cl, OMe); the trans 3 methylcyclohexyl, cis 2 methyl 1,3 dithian 5 yl, cis and trans 2 methyl 1,3 dithian 5 yl tetraoxide, and 1 methylhexyl (open chain) analogues were also prepared. Preliminary tests against murine leukemia L1210 revealed therapeutic indices (ED50/LD10) ranging from 0.26 to 0.79; all but 3 analogues effected 50% cure rates at nontoxic doses, the open chain analogue being one of the least active. In terms of therapeutic index, diequatorial (trans 4) isomers were, with one exception, as active as or, in 4 of the 8 examples, somewhat more active than the corresponding axial equatorial (cis 4) isomers. In this series, 4 of the 5 2-fluoroethyl analogues prepared were clearly inferior to the corresponding 2 chloroethyl analogues.
