Base-induced rearrangement of tritylamines to imines: discovery and investigation of the mechanism

An unexpected compound, the aniline derived benzophenone imine, was isolated when tritylamine was treated with n-BuLi and alkyl halides, during the formation of N-alkyl tritylamines, in the process of preparing primary amines. A nucleophilic attack of the nitrogen anion of tritylamide on the adjacent C-bonded phenyl, either substituted or not, involving a bridging anionic intermediate, is proposed for this base-induced tritylamine rearrangement to produce the corresponding imine. Electron-withdrawing groups in the aromatic ring, favoring the negative charge development, affect the relative migratory tendencies.     

Diastereoselectivity in the Staudinger reaction: a useful probe for investigation of nonthermal microwave effects

The effect of microwave irradiation on the selectivity, especially stereoselectivity, is one of the most important issues in microwave-assisted organic reactions. The diastereoselectivity in Staudinger reactions involving the representative ketenes and the corresponding matched imines has been used as a probe to investigate carefully the existence of the specific nonthermal microwave effects. The results indicate that the microwave irradiation-controlled stereoselectivity in the Staudinger reaction is in fact the contribution of temperature. No specific nonthermal microwave effect was found in the Staudinger reaction.     

Facile Syntheses of Substituted, Conformationally-Constrained Benzoxazocines and Benzazocines via Sequential Multicomponent Assembly and Cyclization

A multicomponent assembly process (MCAP) was utilized to prepare versatile intermediates that are suitably functionalized for subsequent cyclizations via Ullmann and Heck reactions to efficiently construct substituted 2,6-methanobenzo[b][1,5]oxazocines and 1,6-methanobenzo[c]azocines, respectively. The intramolecular Ullmann cyclization was conducted in tandem with an intermolecular arylation that enabled the rapid syntheses of a number of O-functionalized methanobenzoxazocines.     

Diruthenium σ-iminophenylacetylide complexes from on-complex Schiff base condensation

Six diruthenium(II,III) compounds of the formula Ru₂(ap)₄-(CC-C₆H₄-4-NCH-4′-C₆H₄-R) (ap as 2-anilinopyridinate, 3) and Ru₂(ap)₄-(CC-C₆H₄-3-NCH-4′-C₆H₄-R) (4), where R is H (a), Br (b) or CHO (c), were prepared from the condensation reactions between Ru₂(ap)₄(CC-C₆H₄-4/3-NH₂) (1/2) and an appropriate aldehyde. X-ray structural studies of compounds 3a and 3b revealed minimal changes upon the formation of the imine bond in the coordination sphere of the Ru₂ core with respect to the parent compounds. Voltammetric measurements show that compounds 3a/b and 4a/b exhibit four one electron redox processes: an oxidation of Ru₂, two reductions of Ru₂, and a reduction of the imine group. Both compounds 3c and 4c also undergo a fourth reduction attributed to the aldehyde functional group.     

Selective Acceptorless Dehydrogenation of Primary Amines to Imines by Core–Shell Cobalt Nanoparticles

Core–shell nanocatalysts are attractive due to their versatility and stability. Here, we describe cobalt nanoparticles encapsulated within graphitic shells prepared via the pyrolysis of a cationic poly-ionic liquid (PIL) with a cobalt(II) chloride anion. The resulting material has a core–shell structure that displays excellent activity and selectivity in the self-dehydrogenation and hetero-dehydrogenation of primary amines to their corresponding imines. Furthermore, the catalyst exhibits excellent activity in the synthesis of secondary imines from substrates with various reducible functional groups (C=C, C≡C and C≡N) and amino acid derivatives.     

双二茂铁基醛亚胺钼（ＶＩ）配合物的合成及催化性能

通过二茂铁甲醛与丙二胺反应得到双二茂铁基醛亚胺配体N~1,N~3-双二茂铁亚甲基丙烷-1, 3-二胺(FcMP), FcMP与MoO_2Cl_2(THF)_2的四氢呋喃溶液作用, 合成了双二茂铁基醛亚胺钼(VI)配合物. 以配合物为催化剂, 叔丁基过氧化氢为氧化剂, 分别以苯乙烯和环己烯为底物, 考察了温度、时间、催化剂量及溶剂对于烯烃均相环氧化反应的催化性能的影响. 结果表明, 在最优实验条件下, 反应12 h, 环己烯的转化率为88%, 环氧环己烷的选择性为98%;苯乙烯的转化率为84%, 氧化苯乙烯的选择性为76%. 催化剂经简单分离可回收使用, 且催化活性基本保持不变. 同时对环氧化反应的机理进行了初步探讨.     

Characterizing some gossypol and gossypolone Schiff's bases by studying their fragmentation patterns with electrospray ionization tandem mass spectra

To investigate the structural form of gossypol and gossypolone Schiff's bases,seven relevant Schiff's bases were synthesized and the electrospray ionization-tandem mass spectrometry(ESI-MS/MS) with low-energy collision-induced dissociation was used to analyze their fragmentations.A common fragmentation pathway with the loss of RNH_2 from those schiff's bases quasi-molecular ions was observed and proposed on the basis of their MS/MS spectra data.This common pathway indicated that those Schiff's bases exis...