Search results for " Force"

3-(1H-Indol-3-yl)-4-(3,4,5-trimethoxyphenyl)-2,5-dihydro-1H-pyrrole-2,5-dione

2005

The crystal structure of the title compound, C21H18N2O5, was determined in order to study the electrocyclic reactivity of 3,4-di­aryl-1H-pyrrole-2,5-dione derivatives. Intermolecular hydrogen bonds form sheets.

Synthesis of Elemane Bis-Lactones from Santonin – Synthesis of the Reported Structure ofseco-Isoerivanin Pseudo Acid and Formal Synthesis of (+)-8-De…

2000

The synthesis of the reported structure for seco-isoerivanin pseudo acid (1) and of an elemane bis-lactone 5 from santonin (4) through a common vinylic precursor 12 is described. Compound 5 is a known intermediate in a previous synthesis of the antitumor compound (+)-8-deoxyvernolepin (3). The vinyl group of 12 underwent a regio- and diastereoselective anti addition of an external electrophile and an intramolecular condensation to yield either the selenolactone 13 or the hydroxylactone 17. The lactones 13 and 17 served as key intermediates in the total synthesis of 1 and 5 respectively. A revision of the structure of seco-isoerivanin pseudo acid to the C-10 epimer is suggested on the basis …

ChemInform Abstract: A New Tandem Cross Metathesis-Intramolecular Aza-Michael Reaction for the Synthesis of α,α-Difluorinated Lactams.

2012

Difluorinated amides are treated with methyl vinyl ketone or analogous esters to produce the desired γ- and δ-lactam units including optically active versions.

The complexation of tetraphenylborate with organic N-heteroaromatic cations

2001

Complexation studies of eleven N-heteroaromatic cations with tetraphenylborate are reported. Tetraphenylborate forms complexes with five cations and reacts to form Lewis-base boranes with six cations. The complexes and the displacement reaction products were characterised by 1H NMR spectroscopy, elemental analysis and crystallographic methods. In the complexes C–H⋯π or N–H⋯π hydrogen bonds are the principal intermolecular interactions. The stability constants for the complexes are determined by 1H NMR titration in acetonitrile–methanol (1 ∶ 1) solution. Crystal structures of four of the complexes and three of the Lewis-base triphenylborane products are reported.

Intramolecular Cycloaddition Azomethine Ylides and α-(Trifluoromethyl)styrenes as Dipolarophiles

2019

Understanding the Intramolecular Diels-Alder Reactions of N-Substituted N-Allyl-Furfurylamines: An MEDT Study

2017

Recent Advances in the Synthesis of Piperidines: Functionalization of Preexisting Ring Systems

2018

Abstract The present review focuses on strategies for the construction of piperidines which have appeared in the literature since 2003 through mid-2017. In a preceding chapter ( 2017AHC191 ), we summarized synthetic methods involving the construction of the piperidine ring from essentially acyclic starting materials in an intra- or intermolecular manner. The present chapter aims at giving a general overview of decoration or modification of previously generated pyridines or piperidines. The hydrogenation of preformed pyridine or pyridinium rings and introduction of substituents into fully saturated piperidines as well as ring expansion of pyrrolidines to piperidines are the most prevalent me…

The Chemistry of the [1,2,3]Triazolo[1,5-a]pyridines: An Update

2010

Publisher Summary This chapter discusses the recent advancement in the chemistry of [1,2,3] triazolo[1,5-a]pyridines. It describes new discoveries in the physical properties and theoretical chemistry, focusing on synthesis of [1,2,3]triazolo[1,5-a]pyridine system, synthesis of novel aryltriazolopyridines, chiral ligands from [1,2,3]triazolo[1,5-a]pyridines, pyridylcarbene formation from triazolopyridines, ring-chain isomerization on [1,2,3]triazolo[1,5-a]pyridines, and novel pyridylcarbonylpyridines. All triazolopyridines have interesting ligand properties to form polynuclear complexes with different metal ions. X-ray single-crystal studies, magnetic, photo-magnetic, and colorimetric measur…

An approach to polymer-supported triplet benzophenone photocatalysts. Application to sustainable photocatalysis of an α-diazocarbonyl compound

2013

Covalent immobilization of 4-hydroxybenzophenone on Merrifield resins affords new heterogeneous polymeric triplet photocatalysts. Their successful application in the intramolecular triplet-sensitized photolysis of a α-diazo β-keto ester has been achieved under sustainable criteria. Remarkably, the simple recovery and reuse for up to five sequential applications have been performed, although resulting in a slightly decreasing activity.

1983

The kinetics of the electrophilic bromination of 17 oligonuclear phenolic compounds with molecular bromine in acetic acid were studied at 22°C. Some of these compounds, consisting of up to 6 phenolic units, which are linked in ortho-position by methylene bridges, and having only one (or two) reactive ortho-position(s) at the end of the molecule, were synthesized for the first time. It could be shown, even for hexanuclear compounds, that the variation of substituents at one end of the molecule leads to a change in the reactivity at the other end, that means over a distance of 22 nonconjugated covalent links. So far, this can be explained only by a chain of intramolecular hydrogen bonds betwe…