Synthesis and Characterization of Alkoxy Spirophosphoranes Prepared from Hydrospirophosphoranes and Sodium Alcoholates

The Atherton–Todd‐type reaction of hydrospirophosphoranes (HSPs) and sodium alcoholates was investigated. Direct alkoxylation of HSPs was accomplished with sodium alcoholates in acetonitrile under nitrogen atmosphere. The stereochemistry mechanism of the alkoxidation of HSPs was proposed by the ³¹P NMR tracing experiment. The reaction proceeded via the chlorinated spirophosphorane intermediate with stereoretention of the configuration at phosphorus, followed by the rear and front attack of alkoxide anions to produce alkoxy spirophosphoranes. The reaction mechanism well explained the results of the reaction of HSPs with sodium alcoholates.     

On mechanistic aspects of 5-deazaflavin dependent dehydrogenation of alcohol

The reaction of 5-deazaflavins with alcoholates was investigated and the direct hydride equivalent transfer from C₁ of alcoholates to C₅ of 5-deazaflavins was confirmed by chemical methods. 5-Alkoxy-10-butyl-3-methyl-5-deazaflavins were synthesized by treatment of 10-butyl-5-chloro-3-methyl-5-deazaflavin with the corresponding alcoholates. The 5-alkoxy-5-deazaflavins were reduced by sodium borodeuteride or sodium hydro-sulfite in deuterium oxide or monodeuteriomethanol to give 10-butyl-3-methyl-1,5-dihydro-5-deazaflavin-5,5-D₂ exclusively. 3,10-Dimethyl-5-deazaflavin radical anion was detected by esr technique on treatment of 3,10-dimethyl-5-deazaflavin with potassium in DMF. From the above reactions, a mechanism of 5-deazaflavin dependent dehydrogenation of alcoholate was proposed.     

Crystal structure of the alcoholates and the ansolvate of PNU-97018, an angiotensin II receptor antagonist

The title compound, PNU-97018 [systemic name: 2-butyl-3,6,7,8,9,11-hexahydro-6,9-dimethyl-3-([2'-(2H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl)-6,9-ethano-4H-imidazo[4,5-d]-pyridazino[1,2-a]pyridazin-4-one] is a newly developed angiotensin II receptor antagonist. The compound and its methanolate and ethanolate were characterized by X-ray crystallography and thermal analysis. The methanolate and ethanolate crystals have an almost identical molecular conformation and crystal packing. In both alcoholates, each alcohol molecule is fixed to the compound with a molar ratio of 1 : 1 by a hydrogen bond between the hydroxyl group of the alcohol molecule and the tetrazole group of the compound. The hydroxyl group of each alcohol molecule further links with the imidazole ring of the neighboring compound by hydrogen bond to form a hydrogen-bond network in both alcoholates. A tunnel-like structure that includes alcohol molecules is formed in each alcoholate. The ansolvate crystal showed completely different thermal and X-ray crystallographic characteristics from the alcoholates, where the compound molecules were directly linked by hydrogen bonds between the tetrazole group of a molecule and the imidazole ring of the neighboring molecule. The position of the hydrogen atom in the tetrazole ring was different between the ansolvate and alcoholates. Unlike alcoholates, a layer structure stacked on the b-c plane was observed in the ansolvate crystal. It was concluded that the molecular conformation and the arrangement of the compound molecules were largely different between ansolvate and alcoholate crystals.     

One-pot synthesis of selenoureas and selenocarbamates via selenation of isocyanates with bis(dimethylaluminum) selenide

Isocyanates were efficiently selenated by the reaction with bis(dimethylaluminum) selenide to give the corresponding isoselenocyanates. One-pot synthesis of unsymmetrical selenoureas and selenocarbamates was achieved in high yields by the subsequent addition of amines and alcoholates to the reaction mixture.     

Reaction of 2-alkoxy-2-methylthio-5,6-dihydro-4H-1,3-thiazines with phenoxyacetyl chloride

The reaction of 4-alkoxytetrahydro-1, 3-thiazine-2-thiones with methyl iodide and subsequent treatment of the resultant S-alkylation products by suitable sodium alcoholates yielded 4-alkoxy-2-methylthio-S, 6-dihydro-4H-1, 3-thiazines, which upon reaction with phenoxyacetyl chloride in the presence of triethylamine was stereospecifically converted into 4-alkoxy-6-methylthio-7-phenoxvcephams.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 557–560, April, 1996.     

Hydrate and Alcoholate Forms of Phosphomolybdic Heteropolyacid and Their Formation under Conditions of Isothermal Sorption of Water,Methanol, and Ethanol Vapors

Reaction of water, methanol, and ethanol vapors with a solid phosphomolybdic acid at room temperature is accompanied by formation of bulk hydrates and alcoholates. The reaction involves several stages which are readily detected by the sorption and desorption isotherms. The formation of alcoholates causes loosening of the acid lattice, thus favoring much more active initial sorption of alcohols, compared with water, and liquefaction once H₃PMo₁₂O₄₀·11.5CH₃OH and H₃PMo₁₂O₄₀·14.7C₂H₅OH compositions are attained.     

Terpene and Steroid Alkynyl Peroxides

A method was developed for preparation of alkynyl peroxides from terpene and steroid aldehydes and ketones by reaction of lithium peroxyacetylides with the corresponding aldehydes and ketones followed by treating the intermediate lithium alcoholates with acyl chlorides.     

Tandem cyclopropanation with dibromomethane under Grignard conditions

Tertiary Grignard reagents and dibromomethane efficiently cyclopropanate allylic (and certain homoallylic) magnesium and lithium alcoholates at ambient temperature in ether solvents. Lithium (homo)allyl alcoholates are directly cyclopropanated with magnesium and CH2Br2 under Barbier conditions at higher temperatures. The reaction rates depend on the substitution pattern of the (homo)allylic alcoholates and on the counterion with lithium giving best results. Good to excellent syn-selectivities are obtained from alpha-substituted substrates, which are in accord with a staggered Houk model. In tandem reactions, cyclopropyl carbinols are obtained from allyloxylithium or -magnesium intermediates, generated in situ by alkylation of conjugated aldehydes, ketones, and esters as well as from allyl carboxylates or vinyloxiranes. Using this methodology, numerous fragrance ingredients and their precursors were efficiently converted to the corresponding cyclopropyl carbinols.     

Addition reactions and redox esterifications of carbonyl compounds by N-heterocyclic carbenes of indazole

Thermal decarboxylation converts 1,2-dimethylindazolium-3-carboxylate into indazol-3-ylidene, which reacts in situ with ketones to form stable 1:1 adducts. When the reaction is conducted with aromatic aldehydes in alcohols, redox esterifications to benzoates are observed. Model reactions such as redox esterifications of aromatic aldehydes with sodium alcoholates in the presence of 1,2-dimethylindazolium salt and oxidations of sodium benzylates by 1,2-dimethylindazolium salt to aldehydes lend support to a Cannizzaro-type mechanism of this reaction.     

Model reactions for stereochemistry of Ziegler-Natta polymerization: Asymmetric hydroisomerization of α-olefins by chiral titanium tetra-alkoxides/tri-isobutyl aluminum catalytic systems

Homogeneous catalytic systems based on optically active low-molecular-weight and macromolecular titanium alcoholates and tri-isobutyl aluminum were used in the isomerization and hydrogenation of chiral and prochiral olefins. The reactions performed in a nitrogen and hydrogen atmosphere show a different behavior in regard to reaction rate, composition of reaction mixture, and stereochemical control. The catalyst based on macromolecular titanium alcoholate displays lower activity and a varying influence on the stereochemical pathway with respect to the catalysts based on low- molecular-weight alcoholates. The data obtained in both cases strongly support the absence of a stereocontrol by the growing chain in the stereoelective polymerization of racemic α-olefins by Ziegler-Natta catalysts based on optically active precursors. Finally evidence is provided in favor of the intermediate step responsible for asymmetric isomerization which does not occur via η-allyl complex.     

Über Chalkogenolate. LXI. Untersuchungen über Halbester der Kohlensäure. 1. Darstellung und Eigenschaften von Monomethyl- und Monoäthylcarbonaten

On Chalcogenolates. LXI. Studies on Hemiesters of Carbonic Acid. 1. Preparation and Properties of Monomethyl and Monoethyl Carbonates Monoalkyl carbonates M[O₂COR] with M = Li, Na, K, Rb, Cs, Tl, and R = CH₃, C₂H₅ were formed by reaction of CO₂ with alcoholates. The prepared compounds are investigated by different methods.     

Reactions of 2,3-Dichloro- and 2,3,5-Trichloro-4,4-ethylenedioxy-2-cyclopentenones with Some O-, S-, and N-Nucleophiles

2,3-Dichloro- and 2,3,5-trichloro-4,4-ethylenedioxy-2-cyclopentenones react with allyl and benzyl alcoholates and thiolates and benzylamine to give products resulting from Ad_NE substitution of the 3-chlorine atom, [1,3]-sigmatropic rearrangement, and cleavage of the C¹-C² bond.     

Offene und cyclische Stibonigsäureester. III

Esters of Stibonous Acid Antimony tribromide reacts with t-butylmagnesium chloride in the ratio of 1:1 at low temperature under formation of t-butyldibromostibine. The reaction with sodium alcoholates yields t-butyldialkoxistibines. Interchange reactions with 1,2-diols give 2-t-butyl-1,3,2-dioxastiboles and -stibolanes, which do not form coordination polymeres.     

Reactivity and the role of specific solvation in the base-catalysis reactions of ethylene oxide

A study of the distribution of ethylene oxide on reaction with a mixture of two alcohols, or alcohol and water under conditions of base-catalysis, enabled a quantitative dependence between the nucleophilic activity of the alcoholates and the hydroxyl ion to be determined by means of a BrØnsted type equation. Here were detected certain structural groups of alcohols differing in the G-coefficient of this equation. The results obtained enabled an appraisal to be made of the role of specific solvation of the oxide oxygen atom and of the base in reaction with individual alcohols, phenols, and carboxylic acids.     

Framed aromatic polyurethanes based on an anionic macroinitiator, 4,4'-diphenylmethane diisocyanate,and 4,4'-dihydroxy-2,2-diphenylpropane: Synthesis and characterization

Polyurethanes composed of aromatic components are synthesized using the catalytic effect of potassium alcoholates on the reaction of urethane formation occurring with participation of 4,4'-dihydroxy-2,2-diphenylpropane, 4,4'-diphenylmethane diisocyanate, and polyisocyanate, which is a mixture of 4,4'-diphenylmethane diisocyanate and its branched derivatives. In the case of 4,4'-diphenylmethane diisocyanate, segmented polyurethanes with the predetermined length of the rigid block are formed, while the use of polyisocyanate gives rise to framed aromatic polyurethanes. The use of macroinitiators as carriers of potassium alcoholate groups does not cause microphase separation of flexible and rigid segments.     

Offene und cyclische Methylstibonigsäureester. II

Esters of Methylstibonous Acid. II. The reaction of methyldibromstibine with sodium alcoholates and phenolates yield methyldialkoxi and methyldiphenoxistibines. Interchange reactions of the methyldiethoxistibine with thiols, 1,2-diols, 1,2-dithiols, and 2-mercapto-1-oles form dithioesters and cyclic esters of the methylstibonous acid in nearly quantitativ amount and high purity.     

Direct synthesis of 2,5-polychloro-1,2-epoxycyclopentane-1-carboxylic acids and their alkyl esters

The treatment of 3,3,6,6-tetrachloro-1,2-cyclohexanedione with sodium hydroxide gave 2,5,5-trichloro-1,2-epoxycyclopentane-1-carboxylic acid in almost quantitative yield. 3,6,6-Trichloro-2-hydroxy-2-cyclohexen-1-one was also found to be able to undergo a similar reaction providing c-2,t-5-dichoro-1,2-epoxy-r-1-cyclopentanecarboxylic acid, whose structure was confirmed by X-ray crystallographic analysis. The reactions with alkali metal alcoholates gave the corresponding esters in fair to good yields. In contrast to the properties described for further α-chloroepoxides, the prepared compounds show remarkable stability.     

Reactions of aldehydes of the furan series. 3. Oxidative-reductive conversions on the surface of alkali granules

Furan aldehydes undergo an oxidative-reductive disproportionation over solid alkali in a solvent inert to alkali. Molecular oxygen increases the yield of the furan carboxylic acid. A reaction scheme is proposed that takes into account the important role of alcoholates of gem-polyols.For Communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 741–744, June, 1990.     

Synthesis and some reactions of aryl 4,5-dichloroisothiazol-3-yl ketones

By acylation of benzene, toluene, and p-xylene with 4,5-dichloroisothiazole-3-carbonyl chloride the corresponding aryl 4,5-dichloroisothiazol-3-yl ketones were obtained. By reaction of 4,5-dichloroisothiasol-3-yl 4-methylphenyl ketone with piperidine, alkyl(aryl) thiolates, sodium alcoholates, and 2,4-dinitrophenylhydrazine were synthesized 4-methylphenyl 5-piperidyl-4-chloroisothiazol-3-yl ketone, 5-alkyl(aryl)sulfanyl-4-chloroisothiazol-3-yl 4-methylphenyl ketones, 5-alkoxy-4-chloroisothiazol-3-yl 4-methylphenyl ketones, and 2,4-dinitrophenylhydrazone of the initial ketone respectively.