Bi? O chemistry : A direct regioselective route to bismuth bis(amino)naphthalene compounds, incorporating Bi? O and Bi? C bonds is described, in which an amide precursor is treated with aldehydes, ketones, alkenes, and alkynes, leading to insertion into the Bi? NMe2 bond.
A happy ending : The germanium(II) hydride [LGeH], where L=[HC{(CMe)(2,6‐iPr2C6H3N)}2], reacts with a diazoalkane to form the hydrazone derivative (see picture). The reaction proceeds through the unprecedented end‐on nitrogen insertion of the diazo compound.
Monoclonal antibodies are typically glycosylated at asparagine residues in the Fc domain, and glycosylation heterogeneity
at the Fc sites is well known. This paper presents a method for rapid analysis of glycosylation profile of the therapeutic
monoclonal antibody trastuzumab from different production batches using electrospray quadrupole ion-mobility time-of-flight
mass spectrometry (ESI-Q-IM-TOF). The global glycosylation profile for each production batch was obtained by a fast LC-MS
analysis, and comparisons of the glycoprofiles of trastuzumab from different lots were made based on the deconvoluted intact
mass spectra. Furthermore, the heterogeneity at each glycosylation site was characterized at the reduced antibody level and
at the isolated glycopeptide level. The glycosylation site and glycan structures were confirmed by performing a time-aligned-parallel
fragmentation approach using the unique dual-collision cell design of the instrument and the incorporated ion-mobility separation
function. Four different production batches of trastuzumab were analyzed and compared in terms of global glycosylation profiles
as well as the heterogeneity at each glycosylation site. The results show that each batch of trastuzumab shares the same types
of glycoforms but relative abundance of each glycoforms is varied. 相似文献
A chiral epoxidation catalyst based on a tricyclic octahydro-1H-4,7-methanoisoindol-1-one scaffold, in which a hydrogen bonding site and the catalytically active ruthenium center are spatially separated, was synthesized. It was shown that epoxidation reactions in such a supramolecular catalyst occur with high enantio- and regioselectivity because the hydrogen bonds expose the substrate to the ruthenium porphyrin complex with a clear conformational preference. The epoxidation of 3-vinylquinolone proceeded in up to 95% ee (71% yield). 相似文献
Herein, we report the synthesis and characterization of two organozinc complexes that contain symmetrical phenalenyl (PLY)-based N,N-ligands. The reactions of phenalenyl-based ligands with ZnMe(2) led to the formation of organozinc complexes [N(Me),N(Me)-PLY]ZnMe (1) and [N(iPr),N(iPr)-PLY]ZnMe (2) under the evolution of methane. Both complexes (1 and 2) were characterized by NMR spectroscopy and elemental analysis. The solid-state structures of complexes 1 and 2 were determined by single-crystal X-ray crystallography. Complexes 1 and 2 were used as catalysts for the intramolecular hydroamination of unactivated primary and secondary aminoalkenes. A combined approach of NMR spectroscopy and DFT calculations was utilized to obtain better insight into the mechanistic features of the zinc-catalyzed hydroamination reactions. The progress of the catalysis for primary and secondary aminoalkene substrates with catalyst 2 was investigated by detailed kinetic studies, including kinetic isotope effect measurements. These results suggested pseudo-first-order kinetics for both primary and secondary aminoalkene activation processes. Eyring and Arrhenius analyses for the cyclization of a model secondary aminoalkene substrate afforded ΔH(≠) =11.3?kcal?mol(-1) , ΔS(≠) =-35.75?cal?K(-1) mol(-1) , and E(a) =11.68?kcal?mol(-1) . Complex 2 exhibited much-higher catalytic activity than complex 1 under identical reaction conditions. The in situ NMR experiments supported the formation of a catalytically active zinc cation and the DFT calculations showed that more active catalyst 2 generated a more stable cation. The stability of the catalytically active zinc cation was further supported by an in situ recycling procedure, thereby confirming the retention of catalytic activity of compound 2 for successive catalytic cycles. The DFT calculations showed that the preferred pathway for the zinc-catalyzed hydroamination reactions is alkene activation rather than the alternative amine-activation pathway. A detailed investigation with DFT methods emphasized that the remarkably higher catalytic efficiency of catalyst 2 originated from its superior stability and the facile formation of its cation compared to that derived from catalyst 1. 相似文献
Diradicals have been of tremendous interest for over a century ever since the first reports of p‐ and m‐phenylene‐bridged diphenylmethylradicals in 1904 by Thiele and 1915 by Schlenk. Reported here are the first examples of cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon, a Kekulé diradical, and Schlenk's hydrocarbon, a non‐Kekulé diradical, without using CAAC as a precursor. The CAAC analogue of Thiele's hydrocarbon has a singlet ground state, whereas the CAAC analogue of Schlenk's hydrocarbon contains two unpaired electrons. The latter forms a dimer, by an intermolecular double head‐to‐tail dimerization. This straightforward synthetic methodology is modular and can be extended for the generation of redox‐active organic compounds. 相似文献
The subject of this paper are algorithms for measuring the similarity of patterns of line segments in the plane, a standard problem in, e.g., computer vision, geographic information systems, etc. More precisely, we define feasible distance measures that reflect how close a given pattern H is to some part of a larger pattern G. These distance measures are generalizations of the well-known Fréchet distance for curves. We first give an efficient algorithm for the case that H is a polygonal curve and G is a geometric graph. Then, slightly relaxing the definition of distance measure, we give an algorithm for the general case where both, H and G, are geometric graphs. 相似文献
In dendrochronology wood samples are dated according to the tree rings they contain. The dating process consists of comparing the sequence of tree ring widths in the sample to a dated master sequence. Assuming that a tree forms exactly one ring per year a simple sliding algorithm solves this matching task.
But sometimes a tree produces no ring or even two rings in a year. If a sample sequence contains this kind of inconsistencies it cannot be dated correctly by the simple sliding algorithm. We therefore introduce a
algorithm for dating such a sample sequence against an error-free master sequence, where n and m are the lengths of the sequences. Our algorithm takes into account that the sample might contain up to missing or double rings and suggests possible positions for these kind of inconsistencies. This is done by employing an edit distance as the distance measure. 相似文献
The activity of cerium alkoxide complexes supported by a Schiff base ligand was controlled using redox reagents during the ring-opening polymerization of L-lactide. The rate of L-lactide polymerization was modified by switching in situ between the cerium(III) and cerium(IV) species. 相似文献