Search results for "molecule"

Asymmetric Organocatalytic Michael Addition–Cyclization Cascade of Cyclopentane-1,2-dione with Substituted α,β-Unsaturated Aldehydes

2017

An asymmetric organocatalytic Michael addition–cyclization cascade reaction has been developed using cyclopentane-1,2-dione as a Michael donor and α,β-unsaturated aldehydes as Michael acceptors. Bicyclic hemiacetals were obtained in excellent yields and enantioselectivities. On the basis of the results, a one-pot reaction has been developed to obtain chiral 3-substituted cyclopentane-1,2-diones and substituted dihydropyrans in good yields and excellent enantioselectivity.

Dependence of the Substituent Effect on Solvent Properties

2018

The influence of a solvent on the substituent effect (SE) in 1,4-disubstituted derivatives of benzene (BEN), cyclohexa-1,3-diene (CHD), and bicyclo[2.2.2]octane (BCO) is studied by the use of polarizable continuum model method. In all X–R–Y systems for the functional group Y (NO2, COOH, OH, and NH2), the following substituents X have been chosen: NO2, CHO, H, OH, and NH2. The substituent effect is characterized by the charge of the substituent active region (cSAR(X)), substituent effect stabilization energy (SESE), and substituent constants σ or F descriptors, the functional groups by cSAR(Y), whereas π-electron delocalization of transmitting moieties (BEN and CHD) is characterized by a geo…

1H and13C NMR assignments and conformational analysis of some tetracyclic compounds with a bicyclo[4.2.0]octane ring system

1998

Rhodium(III)-catalyzed ring-opening of strained olefins through C–H activation of O-acetyl ketoximes: an efficient synthesis of trans-functionalized …

2013

An efficient strategy for the stereoselective synthesis of functionalized cyclopentenes and spiro[2.4]heptenes from strained olefins via C–H activation of aryl ketone O-acetyl ketoximes using [RhCl2Cp∗]2 catalyst is described. The results revealed that a wide range of readily accessible aryl and heteroaryl ketoximes are compatible in this method for the ring opening of bicyclic and spirotricyclic olefins.

Dimeres und Trimers 1-Methyl-1-aza-5-stannabicyclo[3.3.01,5]-octan sulfid [MeN(CH2CH2CH2)2SnS]n, Röntgenstrukturanalyse des Dimeren und Gleichgewicht…

1991

Abstract The crystal structure of the dimeric title compound has been determined and refined to R = 0.0266. The core of the nearly centrosymmetric dimer is formed by an almost perfect [SnS]2 rectangle (Sn-S 2.39 and 2.51 A). The two sulfur atoms of this rectangle establish the connecting edge of two distorted trigonal bipyramids around the two tin atoms (Sn … N 2.55 A). Solutions of the title compound contain in addition to the dimer (σ(119Sn) = −4.6 ppm) about 20% of the trimer (+ 10.3 ppm). By quick crystallization a mixture of both oligomers can be transferred into the solid state.

Elektronenstoß-induzierte massenspektrometrische Fragmentierung von 2,2′-Bisindolylmethoxy- und Trisindolyl-methanen

1986

An exclusive approach to 3,4-disubstituted cyclopentenes and alkylidene cyclopentenes via the palladium catalyzed ring opening of azabicyclic olefins…

2013

A simple and efficient method for the stereoselective ring opening of bicyclic hydrazines with various aryl halides under palladium catalysis has been elaborated. The reactions afforded trans-3,4-disubstituted cyclopentenes or alkylidene cyclopentenes in good to excellent yields. By taking advantage of multiple points of functionalization in the synthesized trans-3-phenyl-4-hydrazino-cyclopentene, we have synthesized the antidepressant Cypenamine (trans-2-phenylcyclopentylamine).

Coordinating properties of the Cephalexine antibiotic. A potentiometric study of the complexes formation between Cephalexine and Co(II), Ni(II) and C…

1989

Abstract The formation of complexes between Co(II), Ni(II) and Cu(II) with Cephalexine has been investigated using potentiometric techniques. The stability constants of the complexes formed were calculated using the non-linear least-squares computer program SUPERQUAD. The obtained values were: Co(II) logβ1=2.40, logβMLOH=8.89; Ni(II) logβ1=2.80, logβ2=5.10, logβML2OH=12.09; Cu(II) logβ1=4.094 (25 °C, 0.1 M KNO3). The compound [Ni(CEX)(OH2)4]BPh4 has been synthesized and characterized by electronic, IR and NMR spectroscopies as well as by magnetic measurements. From these studies it is proposed that the Cephalexinate anion acts as a bidentate ligand and is bound to the metal ion through the …

New Reactions of Amino-Functionalized 3-Vinyl-1H-indoles and Tetrahydropyridin-4-yl Analogues with Dienophiles

1991

Reactions of 3-[2-(morpholin-4-yl)vinyl]-1H-indole (1), the 1,2-dihydro-9H-carbazole 2, as well as the 3-(tetrahydropyridin-4-yl)-1H-indoles 3a and 3b with some carbo- and heterodienophiles are described. The scope and limitations of the synthetic utility of these amino- (or homoamino)-functionalized 3-vinyl-1H-indoles are reported and some MO calculations for the qualitative prediction of their reactivities are presented. The reactions gave rise to substitution products, redox products, Diels-Alder adducts, ene adducts, and Michael-type adducts (Schemes 2 and 3).

Reactions of 3-(tetrahydropyrid-4-yl)-indoles with dienophiles: new heterocyclic functionalized indoles and pyrido[]annellated carbazoles

1991

First reactions of 3-(1,2,3,6-tetrahydropyrid-4-yl)-indoles 1 with a variety of carbo- and heterodienophiles are described. These reactions provide a new access to heterocyclic functionalized indoles and pyrido[c]annellated carbazoles, compounds of interest as potential antidepressive and antitumor active agents.