Stable perfluorinated cyclic carbanions and their NMR spectra

Conclusions Perfluoro-1-alkylcyclocarbanions were synthesized from perfluoro-1-ethylcyclobutene, perfluoro-1-methylcyclopentene, perfluoro-1-ethylcyclohexene and CsF in DMF and were identified by¹⁹F and¹³C NMR spectra. Perfluoro-1-alkylcyclocarbanions add chlorine to form 1-chloro-1-perfluoroalkylcycloalkanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1325–1331, June, 1986.     

Addition of phosphorus-stabilized carbanions to cyclic enones and further transformations of the reaction products

a-Lithiated diethyl alkylphosphonates react with cyclic enones according to a 1,2-addition, yielding the corresponding allylic alcohols (β-hydroxyalkylphosphonates). The alcohols undergo acid-catalyzed dehydration with preferential exocyclic location of the new olefinic bond; in some cases, allylic rearrangement to a 2° alcohol was observed. In pure methanol, allylic rearrangement is accompanied by the formation of an allyl methyl ether. Lithiated prop-2-enylphosphonate adds to the β-carbon (1,4-addition) via its γ-carbon; the only exception is 3-methylcyclohexenone, in which the methyl group directs the nucleophile toward the carbonyl center. © 1996 John Wiley & Sons, Inc.     

Density functional study of the lithiation of cyclic vinyl ethers in solution

Lithiation of three cyclic vinyl ethers—2,3-dihydrofuran, 3,4-dihydro-2H-pyran, and 2,3-dihydrooxepin in ethereal solution are investigated at the density functional theory level of B3LYP/6-31++G(d,p). Several solvation models were used, including the microsolvation model, the continuum models such as the Onsager model, the polarized continuum models, and the isodensity polarized continuum model, and the mixed discrete-continuum model. Both the microsolvation and the mixed discrete-continuum model gave results consistent with experiments. Theoretical calculations also indicate that lithiation of 2,3-dihydrooxepin undergoes allylic lithiation concomitant with ring opening.     

Characterization of linear and cyclic polylactic acids and their solvolysis products by electrospray ionization mass spectrometry

Linear and cyclic polylactic acids (PLAs) were characterized using electrospray ionization mass spectrometry (ESI-MS) as part of our ongoing investigation of the hydrolysis mechanism of biodegradable polymers. The condensation oligomers of linear polylactic acid (LPLA) were synthesized by thermal dehydration of L-lactic acid. The trimer and tetramer base polymers of cyclic polylactic acid (CPLA) were obtained by cyclization reactions of lactic acid trimers and tetramers, respectively. In the ESI-MS/MS measurement, LPLA yielded three types of product ion series, while CPLA yielded only one type, from which the repeated units of CPLA were removed. The MS/MS spectrum of the NH4+ adduct ion for both cyclic and linear PLA showed loss of one ammonia molecule. The postsource decay (PSD) spectrum of CPLA by matrix-assisted laser desorption ionization (MALDI) mass spectrometry was similar to the ESI-MS/MS spectrum, while that of LPLA was different. In addition, the degradation of cyclic and linear PLAs by solvolysis was investigated. Solvolysis with anhydrous MeOH was quite feasible, but did not readily occur in the presence of even a small amount of water in the MeOH solvent.     

Perfluoroalkylation of carbanions

A successful perfluoroalkylation of various carbanions by the use of per$\text{f}$luoroalkylphenyl$\text{i}$odonium $\text{t}$rifluoromethane$\text{s}$ulfonate (FITS) was described. The reactivity of other perfluoroalkyliodonium salts was also examined.     

‘Counter-intuitive’ regioselectivity, subtle steric and solvation effects in lithiation of cyclic tertiary aralkylamines

Lithiation of a series of cyclic aralkyl tertiary amines with sec-BuLi in various solvents has been studied. There is a subtle sensitivity to steric factors and lithium coordinating solvents/additives have an adverse effect. ortho-Lithiation is observed only in the case of an eight-membered cyclic amine and the ease of benzylic lithiation with respect to nitrogen is in the surprising order γ > β ? α, δ. These observations are discussed in the context of nitrogen coordination promoted lithiation.     

双二茂铁甲氨基醇的合成及其硅烷基化

;双二茂铁甲醇;硅基化;双二茂铁甲氨基醇的合成及其硅烷基化     

Electrode transformations of carbanions and heteroanions

Conclusions The electrolytic oxidation of the 3-nitro-1,2,4-triazole anion is realized through an intermediate radical, which splits out an H atom on reaction with the medium and reacts with benzene to give N-substituted phenyl-3-nitro-1,2,4-triazoles.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1643–1646, July, 1988.     

Synthesis by Si-H bond lithiation of novel half-pincer and pincer silyllithium compounds and their molecular structures

Structural Chemistry - The synthesis and the X-ray structural analysis of novel pincer and half-pincer silyllithiums: Ar2 (N)(tBu2MeSi)SiLi (Ar(N) = o-dimethylbenzylamine) (2a),...     

Allylic lithiation of methylenecyclobutanes

Methylenecyclobutanes undergo a lithiation reaction in the presence of n-BuLi or n-BuLi/KO^tBu from −78 °C to room temperature or to 40 °C in THF within 3 h and then quenching with a variety of electrophiles to give the corresponding addition products (alcohols) in moderate to good yields within 2 h. The alcohols can be easily oxidized to the ketones, which can be transformed to the substituted cyclopentenes in the presence of AlCl₃ within short reaction time.     

Silylation of 6-pyridazone derivatives

Reaction of 6-pyridazone derivatives with hexamethyldisilazan in the presence of small amounts of trimethylchlorosilane gave trimethylsiloxy, bis (trimethylsiloxy), trimethylsiloxy (trimethylsilylamino), and N-trimethylsilylacetamido derivatives of pyridazine, the structures of which as O-trimethylsilyl compounds were confirmed by investigation of their UV, IR, and PMR spectra.     

Nitrosophenols and their rearrangement products

It is shown that the benzene ring is opened (via the scheme of the Beckmann rearrangement) during the nitrosation of 6-hydroxyquinoline and subsequent reaction with acylating agents; the products are -(3-cyano-2-pyridyl)acrylic acids.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 504–508, April. 1971.