Search results for "combinatorial"
showing 10 items of 1208 documents
<strong>QUANTITATIVE QUANTUM MECHANICAL NMR ANALYSIS: THE SUPERIOR TOOL FOR ANALYSIS OF BIOFLUIDS</strong>
2016
Almost automatic quantitative analysis of biofluids is now behind only a few clicks from sample to EXCEL table after minimal sample preparation (move 0.3 ml sample into NMR tube and add buffer), without separations, calibration and reference materials, even for unknown compounds! Each organic compound with protons gives a highly diagnostic and unique NMR spectrum which is practically identical with any spectrometer operating at certain field. A distinctive feature of high-resolution 1D NMR spectra is that even the most complex spectrum of a compound can be described by a few spectral parameters within experimental accuracy, employing a quantum mechanical theory. The NMR spectral parameters…
New Synthesis oftrans-Disubstituted Cyclam Macrocycles – Elucidation of the Disubstitution Mechanism on the Basis of X-ray Data and Molecular Modeling
1998
A new way to synthesize trans-disubstituted cyclam tetraazamacrocycles 1 is reported. The synthesis proceeds in three steps via the tricyclic 1,4,8,11-tetraazatricyclo[9.3.1.14,8]hexadecane system 2, which can be selectively dialkylated and hydrolyzed under basic conditions to give the final product 1. An understanding of the reactivity, based on the X-ray experimental electrostatic potential and molecular modeling of the 1,4,8,11-tetraazatricyclo[9.3.1.14,8]hexadecane macrotricycle, has permitted the elucidation of a new reaction pathway leading to the trans-disubstituted cyclam.
Solid-Phase Synthesis of Oligo(p-benzamide) Foldamers
2006
[reaction: see text] A coupling protocol has been developed which allows the synthesis of oligo(p-benzamide)s on solid support. Aromatic carboxylic acids are activated in situ with thionyl chloride and used to acylate secondary aromatic amines. N-p-Methoxy benzyl (PMB) as well as N-hexyl protected monomers were investigated. Heterosequences of both monomers were synthesized. Such nanoscale objects are important building blocks for supramolecular chemistry.
Topochemical reactions of monomers with conjugated triple bonds. III. Solid-state reactivity of derivatives of diphenyldiacetylene
1971
SYNTHESIS AND REARRANGEMENT OFN-METHYL-N-(2-THIAZOLYL)-NITRAMINE
2001
Methylation of N-(2-thiazolyl)-nitramine in alkaline solution gives 1,2-dihydro-3-methyl-2-nitriminothiazole which rear-ranges in concentrated sulphuric acid yielding small amount of 2-(N-methylamino)-5-nitrothiazole, identical with the product of rearrangement of N-methyl-N-(2-thiazolyl)-nitramine. The latter compound was obtained by the action of sodium hydride on 2-(N-methylamino)-thiazole followed by the nitration with n-butyl nitrate.
ChemInform Abstract: Electroorganic Synthesis of Nitriles via a Halogen-Free Domino Oxidation-Reduction Sequence.
2016
A direct electroorganic sequence yielding nitriles from oximes in undivided cells is reported. Despite the fact that intermediate nitrile oxides might be formed, the method is viable to prepare benzonitriles without substituents ortho to the aldoxime moiety. This constant current method is easy to perform for a broad scope of substrates and employs common electrodes, such as graphite and lead.
A New Tandem Cross Metathesis-Intramolecular Aza-Michael Reaction for the Synthesis of α,α-Difluorinated Lactams
2012
A new tandem cross metathesis–intramolecular aza-Michael reaction in which an α,α-difluorinated amide serves as a source of nucleophilic nitrogen is described. This process gives rise to a new family of fluorinated γ- and δ-lactams. The tandem protocol is catalyzed by the Hoveyda–Grubbs second-generation ruthenium catalyst with titanium(IV) tetraisopropoxide as a co-catalyst and it is highly efficient when conjugated ketones are used as the Michael acceptors. With conjugated esters, however, it is necessary to perform a step-by-step procedure in which the cyclization event is activated by the addition of a base. An asymmetric version of the process is also evaluated.
ChemInform Abstract: Cooperative Assistance in Bifunctional Organocatalysis: Enantioselective Mannich Reactions with Aliphatic and Aromatic Imines.
2013
both of which contain a thiourea moiety (Scheme 1).The catalysts are capable of deprotonating suitable nucleo-philes, such as activated carbonyl compounds. This proton-transfer reaction generates an ion pair, which is composed ofthe protonated catalyst and the anionic nucleophile interact-ing through hydrogen bonds. At least one of the NH moietiesin the protonated catalyst is involved in activating theelectrophilic reaction partner.
Diastereoselective Synthesis of Enantioenriched Trifluoromethylated Ethylenediamines and Isoindolines Containing Two Stereogenic Carbon Centers by Nu…
2020
Fluoroform, HFC-23, is an industrial byproduct from the synthesis of polytetrafluoroethylene and is a vastly underused resource; however, its physicochemical properties have hindered progress toward synthetic uses. Herein, we describe the use of HFC-23 as a cheap trifluoromethylating agent in two reactions for the highly diastereoselective synthesis of medicinally attractive chiral amines with two stereogenic carbon centers: a base-dependent, stereodivergent nucleophilic addition to synthesize enantioenriched vicinal diamines and a tandem nucleophilic addition/aza-Michael sequence toward enantioenriched isoindolines.