Alkoxycarbonyl Group Research Articles

ChemInform Abstract: SYNTHESIS AND PROPERTIES OF 3‐OXA‐7,11‐DIAZASPIRO(5.6)DODECANES

A method for the synthesis of 2,2-dialkyl-3-oxa-7,11-diazaspiro[5.6]dodecanes was developed on the basis of 4-bromo-4-formyltetrahydropyrans. The products were alkylated at the nitrogen atom in the 11 position by means of alkyl halides and acrylic acid derivatives, and the alkoxycarbonyl groups in the side chain were reduced.

Thermal and Dielectric Properties of Liquid Crystals with a Coumarin Skeleton

Abstract In order to examine the liquid crystalline properties of coumain, 3-X- and 7-Y-substituted coumarins where X=cyano and n-alkoxycarbonyl, and Y=4-n-alkyl- and 4-n-alkoxybenzoyl, 4-alkoxycinnamoyloxy, 4′-alkyl- and 4′-alkoxy-4-biphenylylcarbonyloxy, and 4-(4-alkoxybenzoyloxy)benzoyloxy (4) groups have been prepared. The compounds with X=alkoxycarbonyl group tend to exhibit strong smectic properties, and compounds with X=cyano exhibit stable nematic phases, whereas the coumarin core seems to facilitate a lateral separation of molecules in the mesophase due to its large molecular breadth. The heptyloxy homolog of 4 exhibits a reentrant behavior of the C–Nre–SA–N–I type. The thermal properties are discussed in terms of the polarity and polarizability of coumarin, and the molecular structure. The dielectric properties of the compounds have also been examined and discussed in terms of the polarity of the coumarin core.

Synthesis and properties of 3-oxa-7,11-diazaspiro[5,6]dodecanes

A method for the synthesis of 2,2-dialkyl-3-oxa-7,11-diazaspiro[5.6]dodecanes was developed on the basis of 4-bromo-4-formyltetrahydropyrans. The products were alkylated at the nitrogen atom in the 11 position by means of alkyl halides and acrylic acid derivatives, and the alkoxycarbonyl groups in the side chain were reduced.

Photolyses of [2-Substituted 2-(alkoxycarbonyl)propyl]cobaloximes

Abstract Photolysis of (2-methoxycarbonyl-2-phenylpropyl)cobaloxime (1) gives two phenyl-migrated products, methyl 2-methylene-3-phenylpropanoate and methyl trans-2-methyl-3-phenylpropenoate, and a hydrogen-abstracted product, methyl 2-methyl-2-phenylpropanoate. The alkoxycarbonyl groups do not migrate in the photolysis of either 1 or [2,2-bis(ethoxycarbonyl)propyl]cobaloxime.

Metalloesters, 8. Esters of diacids and oligo(carboxylic acid)s (oligomers of methyl methacrylate) substituted in α‐position with an alkali metal. Their stability and IR Spectra

AbstractEsters of diacids and oligo(carboxylic acid)s substituted in α‐position with Li, Na, or K (models of the propagation site in the anionic polymerization of methyl methacrylate (MMA)) were prepared, and their IR spectra were recorded. In the range 1600 – 1800 cm−1, their absorption of the Mt+ group in benzene solution was reflected in a band between 1630 and 1645 cm−1, depending on the counterion. In the presence of THF or of tert‐butoxide of the same alkali metal this band appears between 1626 and 1660 cm−1. Coordination of the more remote alkoxycarbonyl group (e.g., in γ‐position) to the counterion is demonstrated by a band near 1712 cm−1; its absorbance is much lower in the presence of THF. In solution, the metalloesters undergo autocondensation, the rate of which increases dramatically with the number of monomeric units. Thus, in benzene at 25 °C ethyl 2‐lithioisobutyrate is stable for more than a week, whereas the half life of dimethyl 2‐lithio‐2,4,4‐trimethylglutarate (Li‐dimer, 3b) is <24 h, and the Li‐trimer (5a), Li‐tetramer (5b), and Li‐pentamer (5c) completely decompose in less than 4 min under these conditions. The decomposition may be slowed down by adding tert‐butoxide of the same alkali metal. In THF the decomposition proceeds much more quickly. The properties of models used in this study are compared with those of the propagation site in the anionic polymerization of MMA.

Mutagenicity of 4,4?-MethyIenedianiline Derivatives in the Salmonella histidine reversion assay

4,4'-Methylenedianiline and its derivatives were assayed for mutagenicity in the Salmonella/microsomal mutagenicity assay develop by Ames. A specificity to revert strain TA98 suggests a mechanism of frameshift mutagenesis. Liver microsomal preparations (S-9) from rats induced with phenobarbital were most effective for metabolic activation. Alkyl substitution of 4,4'-methylenedianiline did not alter its mutagenic activity; however, substitution of both positions ortho to the amino group eliminated mutagenic activity. Substitution with alkoxy-carbonyl groups eliminated mutagenic activity, whereas halogen substitution (chlorine, fluorine) enhanced the mutagenic activity. The results presented here show the use of structure-activity studies as predictive tools for the assessment of genotoxic properties of industrial chemicals.

Ternary Copolymerization of Trimethylvinyloxysilane, Styrene, and Acrylic Esters Catalyzed by Organoaluminum Compounds

The ternary copolymerization of trimethylvinyloxysilane, styrene, and methyl or phenyl acrylate was attempted in the presence of organoaluminum compounds at 0°C. All copolymers had a considerable amount of five-membered lactone structures in their backbone chains following the hydrolysis of the trimethylsiloxy group. These copolymers originally had a 1:1 composition between acrylate as an electron acceptor and the other two components as electron donors, and therefore could be recognized as copolymers of two alternating units, trimethylvinyloxysilane–acrylate and styrene–acrylate. The conversion of lactonization was often beyond 86.5% (Flory’s limit) being nearly 100%, especially in copolymers containing the phenyl acrylate component. Additional lactonization of the copolymers did not occur under the same conditions used in the work-up process. Hence, the realized conversion resulted from a statistical intramolecular reaction between trimethylsiloxy and alkoxycarbonyl groups. These terpolymers may thus be regarded as a model of the “specially-designed alternating copolymer” described in the preceding paper.

Synthesis of 4-acyl- and 4-alkoxy-carbonylpyrazoles

N′-Aroyl- or N′-acetyl, N′-phenyl- or N′-methyl-hydrazino-derivatives (1) of 1,3-dicarbonyl compounds can be converted by mild base treatment into 5-aryl- or 5-methyl-, 1-phenyl- or 1-methylpyrazoles carrying an acyl or alkoxycarbonyl group at C-4.

Electrophilicity of perfluoroisobutylene and methyl perfluoromethacrylate

1. Interaction of m- and p-fluorophenylmagnesium bromide with perfluoroisobutylene or with methyl perfluoromethacrylate gives the corresponding arylperfluoroisobutylenes and methylα-trifluoromethyl-β-fluoro-β-arylacrylates. 2. Examination of the19F NMR spectra of substituted m- and p-fluorobenzenes reveals that the unsaturated units CF=C(CF3)X and trans-CH=CHX have a greater deshielding effect on the fluorine nucleus in C6H4F when X=CF3 than when X=CO2Me. 3. Extended Huckel and CNDO/2 calculations on methyl perfluoromethacrylate and perfluoroisobutylene reveal that the negative π-electron charge on the “central” carbon atom is more efficiently delocalized by the methoxycarbonyl group than the trifluoromethyl. 4. The higher electrophilicity of methyl perfluoromethacrylate relative to perfluoroisobutylene stems from the greater ability of the alkoxycarbonyl group to stabilize the intermediate carbanion or the carbanion-like transition state in the reaction with the nucleophile.

Mass Spectrometric Studies. XIII. Spirocyclic Glycidic Esters

The mass spectra of a series of spirocyclic glycidic esters derived from cyclo-butanones, -pentanones, -hexanones, -heptanones and -octanones show the following characteristic fragmentations: (i) a rearrangement involving migration of the ester alkoxy group to the ring junction, followed by elision of the group COCR=O (R = H or Me), and (ii) loss of the alkoxycarbonyl group by α-fission, followed by ring-contraction and loss of the elements of acetaldehyde. The major fragmentations are supported by deuterium-labelling experiments, and a number of minor decompositions are described.

Amino-acids and peptides. Part 41. An examination of some new amino-protecting groups

In an investigation of the effect of the introduction of basic sites on the stability of alkoxycarbonyl groups to acid the following new amino-protecting groups have been examined: di-2-pyridylmethoxycarbonyl [e.g. (1)], 4-pyridylisopropoxycarbonyl [e.g. (4)], 3-diethylamino-1.1-diphenylpropoxycarbonyl [e.g. (10)], and 1,4-dimethylpiperidin-4-yloxycarbonyl [e.g. (13)]. In each case the stability to acid is considerably enhanced. The lastnamed group provides protection which is more stable to trifluoroacetic acid than is the t-butoxycarbonyl group, is stable to hydrogenolysis, and is cleaved by hydrogen bromide in acetic acid. In an investigation of amino-protecting groups designed to increase the solubility of derivatives by the incorporation of dimethylcarbamoyl substituents, the preparation of 2-dimethylcarbamoylethyl-isopropoxycarbonyl [e.g. (18)] and 2-dimethylcarbamoylbenzyloxycarbonyl [e.g. (24)] amino-acid isreported.

Electron capture by molecules containing an alkoxycarbonyl group

1. Dissociative electron capture by molecules containing an alkoxycarbonyl group has been investigated through study of mass spectra. In the absence of other groupings, the ester group is determinant in fixing the direction followed in such processes. 2. The relative probability of ion formation depends on the stability of the product ion and the structure of the eliminated neutral splinter.

Synthesis of 21-hydroxycholesterol and 25-hydroxycholesterol from 3β-hydroxyandrost-5-en-17-one. A method for the stereospecific construction of sterol side-chains

Alkylation of lithium derivatives of the ethyl and methyl esters of 3β-tetrahydropyran-2-yloxypregn-5-en-21-oic acid (3a) and (3c) with 1-bromo-4-methylpentane gave corresponding derivatives of cholest-5-en-21-oic acid, which were converted into 21-hydroxycholesterol (5e) by reduction of the alkoxycarbonyl groups and acid hydrolysis of the ether group. Alkylation of lithium derivatives of esters (3a) and (3c) with 2-(3-bromopropyl)-2-methyl-1,3-dioxolan (8) followed by conversion of the alkoxycarbonyl groups into a methyl group and removal of the protecting groups gave 3β-hydroxy-27-norcholest-5-en-25-one (7a) which was converted into 25-hydroxycholesterol (7c). Alkylation of the lithium derivative of the ester (3c) with methyl iodide gave methyl (20R)-3β-hydroxy-24,25-bisnorchol-5-en-22-oate (4b).

Poly(mono n‐alkyl itaconic acid esters): Their preparation and some physical properties

AbstractA series of poly(mono n‐alkyl itaconic acid esters), with ester chain lengths varying from methyl to decyl, were prepared by emulsion polymerisation. The materials are all hard brittle glassy polymers at ambient temperatures and undergo a dehydration reaction in the range 430 K to 450 K. Dynamic mechanical measurements showed the presence of at least three other damping maxima: an Δ‐transition at 90−95 K, a δ‐transition at 190–200 K and a γ‐transition at 240–260 K. The ε is associated with motion in the hydrocarbon part of the side chain, while the δ and γ transitions are associated with relaxations involving the carboxyl and alkoxycarbonyl groups respectively. Glass transitions were only detectable in higher esters. The thermal stability of the polymers is also briefly discussed.

Syntheses based on 1,2-secopenicillins. Part 5. Penicillin analogues with electron-withdrawing 2-substituents

6-Acylaminopenam-3-carboxylic esters substituted at C-2 by one or two alkoxycarbonyl groups or by an acetyl group have been prepared from penicillins. The azetidinone ring remained intact throughout the reaction sequence, and the thiazolidine ring was completed by intramolecular alkylation at an activated methylene or methine group adjacent to the sulphur atom. Only in the case of the 2-alkoxycarbonylpenams could stable carboxylic acids be liberated from the esters.

Polar selectivity of carbene addition to 3-substituted propenes

Relative rate constant for the addition of several carbenes to a series of allylic compounds have been determined by means of competititive experiments. These results and derived Hammett–Taft parameters show that polar selectivities of carbenes are generally low, but correlate with the polar natures of the carbene substituents. The selectivity of a singlet carbene was even lower than that of the corresponding triplet state. These facts support a mechanism of addition of singlet carbene involving a transition state having only a slight contribution from polar structures. Low selectivities of alkoxycarbonylcarbenes suggest that the –R effects of the alkoxycarbonyl groups do not affect the addition reactivities of the carbenes.

Rearrangements Involving alkoxycarbonyl group migration between nitrogen and oxygen.III. Reactions of modified isoquinoline Reissert compounds with aldehydes

The condensation reaction of modified Reissert compounds with aldehydes was investigated. In the reaction of the N-ethoxycarbonyl Reissert analog 1b, ethoxycarbonyl group migration takes place and carbonates of 1-isoquinolylphenylcarbinols (2b, c) are formed. No alkoxycarbonyl group migration was observed in the case of the dihydro-Reissert derivative 6, but the cyclic urethane 7 and the amide 8 were obtained.

Transition metal complexes of ligands containing azomethine group. V. Stereochemistry and reactivity of four-coordinate nickel(II) complexes derived from (S)-(+)-cysteine derivatives

By the condensation of salicylaldehyde (acetylacetone) with (S)-(+)-cysteine ester in the presence of Ni 2+ ions, diamagnetic, binuclear, square-planar Schiff base complexes were prepared. Their circular dichroism spectra show negative Cotton effect due to the stereospecific coordination of the chiral ligand. From the PMR spectra it follows that complexes in solution exist in preferred δ conformation with the axial COOR group. From the ligand field spectra and magnetic moments it was deduced that in donor solvents complexes exist as monomeric hexa-coordinate ones. In addition, alkoxycarbonyl group undergo ester exchange which is facilitated by the inductive effect of CHN group. Although complexes were prepared in the presence of base, they did not undergo racemisation. Increased optical stability was ascribed to unfavourable conformation of the complex.

Fluxional isomerism of a malonate anion ? an instance of intramolecular homoconjugate addition

The rapid interconversion of two cyclopropanes bearing two alkoxycarbonyl groups at the 1-position and a ββ-dialkoxycarbonylethyl group at the 2-position, via their anions, has been observed.

Studies on Geometrical Isomerism by Nulear Magnetic Resonance. V. Stereochemistry of 5-Substituted 4-Alkoxycarbonyl-2-carbamoylimino-1,3-oxathiolanes

Abstract An equimolar reaction of thiocyanoacetic esters with aldehydes in the presence of potassium fluoride or carbonate leads to a stereoisomeric mixture of cis and trans isomers of 5-substituted 4-alkoxycarbonyl-2-carbamoylimino1,3-oxathiolanes. Several of them were separated into two isomeric forms, whose geometrical configurations were determined by means of nuclear magnetic resonance technique. The vicinal coupling constant between the 4-and 5-protons is consistently larger for the cis forms than for the trans. In the case of the 5-aryl derivatives, the signals of the alkoxycarbonyl group appear at higher field for the cis isomers than for the trans. The composition ratios of cis and trans isomers of the oxathiolanes prepared are determined. Infrared data of the cis and trans oxathiolanes are also reported.