Preparation Of Cis Research Articles

Stereospecific thermal cycloadditions and catalyzed isomerizations: An organic laboratory project

The authors have prepared a sequence of experiments for their undergraduate organic chemistry laboratory concerned with the preparation of cis and trans 1,4-diphenyl-2-butene-1,4diones, their cycloadditions reactions with cyclopentandiene, and with related isomerization reactions of both the sequence, which has met with much success experimentally, clearly and collectively demonstrates certain aspects of the concepts of thermodynamics, kinetics, and stereochemistry and photochemistry.

Preparation of cis and trans isomers of 4-phenylcyclohexyl and 4-cyclohexylcyclohexyl bromides

Preparation of cis and trans isomers of 4-phenylcyclohexyl and 4-cyclohexylcyclohexyl bromides

1,10-Phenanthroline and 2,2′-bipyridyl complexes of rhodium(III)

The preparation of cis-[Rh(aa)2Cl2]+(aa = 2,2′-bipyridyl or 1,10-phenanthroline) has been re-examined and shown to be catalytic. The preparation and characterisation of cis-[Rh(aa)2X2]n+(X = I–, CN–, H2O, and NH3) and cis-[Rh(aa)2ClY]m+(Y = H2O, NH3, pyridine, and NO2–) is described and the possible mechanisms of base hydrolysis and of substitution by cyanide and by iodide into cis-[Rh(aa)2Cl2]+ are discussed; the effect of dioxygen on these substitutions is also discussed. The resolution of cis-[M(aa)2Cl2]+(M = Rh or Ir) into optical isomers is described and their stability is discussed. A convenient catalytic preparation of [Rh(aa)3]3+ is given.

Preparation of cis- and trans-cyclodec-2- and -3-enones and studies of interconversions between them

The cis- and trans-cyclodec-2- and -3-enones have been synthesised by stereospecific routes; a preparation of 3-hydroxycyclodecanone has also been developed. Under conditions of acid catalysis cis- and trans-cyclodec-2-enones are rapidly interconverted to give an equilibrium mixture containing 96% of the cis- and 4% of the trans-isomer. Efficient equilibration with the unconjugated isomers was not achieved. Deuteriation of the unsaturated ketones has given information on their relative ease of enolisation and the position of protonation (deuteriation) of the respective enols.The acid-catalysed isomerisation of trans- to cis-cyclodec-2-en-1-ol has been studied by use of [1-2H]-labelled substrates.

Preparation and Structural Elucidation of cis-and trans-Phenyl-2-methylcyclohexanol

The preparation of cis- and trans-1-phenyl-2-methylcyclohexanol by hydrolysis of an isomeric mixture of the corresponding hydrogen phthalate esters is described. The elucidation of the structures of the alcohols is also described.

Preparation of cis and trans‐α‐d‐3‐alkenoic acids

Preparation of cis and trans‐α‐d‐3‐alkenoic acids

The Preparation and Cyclopolymerization of cis- and trans-l,3,5-Triisocyanatocyclohexane

Abstract The preparation of cis- and trans-1,3,5-triisocyanatocyclohexane is described. The coupling constants JAB, JAX> and JBX were obtained from the NMR spectrum of the cis-isomer. Both isomers were polymerized using sodium cyanide in N,N-dimethylformamide as initiator. The evidence indicated that cyclopolymerization had occurred and, in both cases, predominantly bicyclic structures obtained.

Quinazolines. Part XV. Hexahydro- and octahydro-quinazolines

3,4,5,6,7,8-Hexahydroquinazoline, obtained by catalytic reduction of 5,6,7,8-tetrahydroquinazoline, was slowly oxidised by air to the starting material in chloroform solution, but in aqueous alkali it was degraded to 2-formamidomethylcyclohexanone. trans-4a,5,6,7,8,8a-Hexahydroquinazolin-4(1 - or 3-H)-one was shown to be a tautomeric mixture of the (1H)-one (20%) and (3H)-one (80%) in pH 9·2 aqueous buffer by comparing the u.v. spectrum with those of authentic 1- and 3-methyl derivatives. The preparations of cis- and trans-3,4,4a,5,6,7,8,8a-octahydroquinazoline hydrochlorides, 2-amino-3,4,4a,5,6,7,8,8a-octahydroquinazolin-4-ones, 2-amino-3,4,4a,5,6,7,8,8a-octahydroquinazoline salts, 2-oxo(1H) and 2-thio(1H)3,4,4a,5,6,7,8,8a-octahydroquinazolines, 1,2,4a,5,6,7,8,8a-octahydroquinazolin-4(3H)ones; cis-4a,5,6,7,8,8a-hexahydroquinazolin-4(3H)one, cis-2-amino-4,5-dihydro-4,5-tetramethylene-1,3(6H)-oxazine and thiazine, and cis-2,3,4,5-tetrahydro-2-oxo-4,5-tetramethylene-1,3(6H)-oxazine are described. The 1H n.m.r. spectra of cis- and trans-octahydroquinazolines show spectral patterns for the 4,4a,5,6,7,8 and 8a-protons which are similar to those of cis- and trans-decahydroquinazolines respectively and are characteristic of the stereochemistry.

The preparation of cis- and trans-1-alkyl-4-phthalimidocyclohexanes

Mixtures of cis- and trans-4-alkylcyclohexylamines (alkyl = methyl, ethyl, isopropyl, s-butyl, cyclohexyl, and t-butyl) have been prepared by standard methods and have been converted into stereochemically pure cis- and trans-1-alkyl-4-phthalimidocyclohexanes.

Reduction products from cis- and trans-isocohumulone

The preparations of cis- and trans-tetrahydroisocohumulone, (IV) and (V), cis- and trans-neohydroisocohumulone, (VI) and (VII), and cis- and trans-ρ-tetrahydroisocohumulone, (IX) and (X), from colupulone are described. Reduction of trans-tetrahydroisocohumlone (V) with hydrogen over palladised charcoal gives, in addition to (VII), 4-hydroxy-2-isobutyryl-4-isohexanoyl-5-isopentylcyclopentan-1-one (VIII). Reduction of cis-tetrahydroisocohumulone (IV) with sodium borohydride gives 3,4-dihydroxy-4-(1-hydroxy-4-methylpentyl)-2-isobutyl-5-isopentylcyclopent-2-en-1-one (XI) as well as cis-ρ-tetrahydroisocohumulone (IX).

Tungsten chloride fluorides: the preparation of cis- and trans-tungsten dichloride tetrafluoride and its decomposition into other tungsten fluorides

Tungsten dichloride tetrafluoride has been prepared and found to consist of both cis- and trans-forms. The isomers are apparently in equilibrium and have not been separated by physical or chemical techniques. The compound is thermally unstable at room temperature, decomposing to tungsten hexachloride and tungsten hexafluoride. Other chloride fluorides of tungsten(VI) have been identified by 19F n.m.r. spectroscopy. The stability of cis- and trans-tungsten dichloride tetrafluoride is discussed.

Phosphine-substituted carbonyl halide complexes of chromium and molybdenum

A number of phosphine tetracarbonyl halide salts of the Group VI metals have been prepared of the type: cis-[Et4N][PR3M(CO)4X] where PR3 = (p-FC6H4)3P or (p-ClC6H4)3P, M = Cr or Mo for X = Cl, and M = Mo for X = Br, by the reaction of phosphines with the pentacarbonyl halides [Et4N][M(CO)5X]. A new method for the preparation of cis-[Formula: see text] complexes from the phosphine tetracarbonyl halides is described.Assignments are made for the bands in the carbonyl stretching region of the infrared spectra of these complexes.

Preparation of cis- and trans-p-Dithiane-2,3-dicarboxylic Acids and Optical Resolution of the Latter.

Preparation of cis- and trans-p-Dithiane-2,3-dicarboxylic Acids and Optical Resolution of the Latter.

The preparation of cis- and trans-2-alkyl-NN-dimethylcyclohexylamines

Mixtures of cis- and trans-2-alkyl-NN-dimethylcyclohexylamines have been prepared by standard methods and the majority have been separated into pure isomers by preparative VPC.

The preparation of cis-[Cr(pn) 2X 2]X and cis-[Cr(tm) 2X 2]X complexes by the thermal matrix method

The preparation and characterization of the cis-[Cr(pn) 2X 2]X and cis-[Cr(tm) 2X 2]X complexes by the thermal matrix reaction are described. In general, higher temperatures were required to prepare the cis-complexes than was previously observed for the 1,2-ethanediamine complexes. The order of deamination appears to be: 1,2-ethanediamine > 1,2-propanediamine > 1,3-propanediamine

The synthesis and stereochemistry of some isatylideneacetic acid derivatives

Abstract The preparations of cis - and trans -1-benzylisatylidene-3-acetaldehyde, cis - and trans -1-benzylisatylidene-3-acetic acid and some derivatives are described. Structures are assigned on the basis of NMR and p K a measurements.

Dehalogenative Decarboxylation and Other Elimination Reactions of 2,3-Dibromo-2-methylsuccinic Acid. The Preparation of cis- and trans-3-Bromomethacrylic Acid.

Dehalogenative Decarboxylation and Other Elimination Reactions of 2,3-Dibromo-2-methylsuccinic Acid. The Preparation of cis- and trans-3-Bromomethacrylic Acid.

Determination of the configurations of the stereoisomers of 3-benzoylacrylonitrile

1. Methods were developed for the preparation of cis- and trans-3-benzoylacrylonitriles. 2. The geometric configurations of these isomers were established on the basis of chemical correlations and measurements of the IR and NMR spectra and of dipole moments.

Preparation of cis- and trans-2,3-Dimethyl-2,3-dihydrobenzofurans and Related Compounds. Cyclizations Involving Oxonium Ions1

Preparation of cis- and trans-2,3-Dimethyl-2,3-dihydrobenzofurans and Related Compounds. Cyclizations Involving Oxonium Ions¹

The preparation of cis-[Cr(en) 2X 2]X type complexes by the thermal matrix method

The preparation of cis-[Cr(en) 2X 2]X type complexes by the thermal matrix method is described. The preparative procedure consisted of heating [Cr(en) 3]X 3 mixed with an excess of an appropriate ammonium salt at temperatures from 80 to 230°C. At the completion of the reaction, the excess ammonium sa;t was removed by sublimation in vacuo. Yields of the cis-[Cr(en) 2X 2]X complexes were essentially quantitative. A possible mechanism for the reaction is also given.