Reversible redox behavior between stannole dianion and bistannole-1,2-dianion

The reversible redox behavior between the stannole dianion and the bistannole-1,2-dianion is demonstrated. Reaction of the stannole dianion with oxygen (1 eq) gives the 1,2-bistannole-1,2-dianion which is a tin-analogue of the cyclopentadienyl anion in 94% yield. Reaction of the stannole dianion with ferrocenium tetrafluoroborate (1 eq) also gives the 1,2-dianion. The 1,2-bistannole-1,2-dianion has a nonaromatic nature as evidenced by X-ray and NMR analysis. Reduction of the 1,2-dianion with lithium gives the starting dianion.     

Stepwise oxidation of the stannole dianion

Tin oxidation of stannole dianion 1 with 1.3 equivalents of oxygen gave terstannole-1,3-dianion 3. The non-aromatic nature of 3 was confirmed by X-ray crystallographic analysis. Treatment of 1 with 1,2-dibromoethane (3 equiv) gave poly(1,1-stannole) 4, the formation of which was proven by reduction of 4 with lithium to revert to the starting dianion 1. Reaction of 1 with 1,2-dibromoethane (3 equiv) in the presence of phenyllithium gave phenyl-capped ter(1,1-stannole) 7. The electronic absorption spectra of newly obtained stannoles were also measured.     

Antiaromatic dianions: dianions of dixanthylidene by reduction and attempted excited-state deprotonation

Reduction of dixanthylidene with potassium or lithium resulted in formation of the antiaromatic dianion in high yield. Attempts to form the dianion by excited-state deprotonation of dixanthene with n-butyllithium/TMEDA resulted in formation of the tetraanion from deprotonation ortho to the oxygen. Orientation of the sp(3) hydrogens presumably allows preferential deprotonation of the xanthene rings.     

The enolate-imine condensation using lithium dianion of 3-hydroxybutanoate and N-acylaldimines: Enhanced stereoselectivlty by added lithium chloride

An enolate-imine condensation using the lithium dianion of 3-hydroxy-butanoate and N-acylaldimines gave the key intermediate for the preparation of (+)-thienamycin with improved stereoselection in the presence of lithium chloride.     

Reactions of metallated 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole with functionalized nitroxyl radicals derived from 2,5-dihydro-1H-imidazole and 2,5-dihydro-1H-imidazole 3-oxide

The reactions of the dianion generated from 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole under the action of lithium diisopropylamide with nitroxyl radicals derived from 2,5-dihydro-1H-imidazole or 2,5-dihydro-1H-imidazole 3-oxide and containing the ester, aldehydo, cyano, or imino groups afforded biradicals, including those containing the enamino ketone and enamino imine functions. The reactions of this dianion with nitriles derived from 2,5-dihydro-1H-imidazole 3-oxide gave rise to an enamino nitrile, i.e., electrophilic cyanation formally occurred.     

New reactions of a dibenzo[a,e]pentalene

Reduction of dibenzo[a,e]pentalene 3 (denoted as dibenzopentalene hereafter) with excess lithium gave dilithium dibenzopentalenide 1. Since oxidation of 1 with iodine gave 3, redox behavior between 1 and 3 is controllable and reversible. Reaction of 3 with methyllithium gave lithium 5-methyldibenzopentalenide 5, the formation of which was evidenced by some trapping experiments and X-ray crystallographic analysis. Reactions of 3 with halogens gave 5,10-dihalodibenzopentalenes, 8 and 9. Some optical properties of novel dibenzopentalene derivatives are also demonstrated.     

Nucleophilic reactions of 1-methyl-2-methoxy-2-phenyl-3-oxo-2,3-dihydroindole

The title compound (1) was prepared via methylene blue (MB)-sensitized photooxy-genation of l-methyl-2-phenylindole (2d) in methanol. Acid-catalyzed nucleophilic substitution of 1 with nucleophiles gave 1,2,2-trisubstituted 3-oxo-2,3-dihydroindoles (3-6). Reduction of 1 with lithium aluminum hydride, followed by acidic workup yielded 4d and 2d, whereas the same reduction reaction of 1, followed by neutral workup gave l-methyl-2-phenyl-3-hydroxy-2,3-dihydroindole (15), together with 3. The reaction pathways of nucleophilic substitution and reduction of 1 were discussed.     

Nucleophilic reactions of l-methyl-2-methoxy-2-phenyl-3-oxo-2,3-dihydroindole

The title compound (1) was prepared via methylene blue (MB)-sensitized photooxy-genation of l-methyl-2-phenylindole (2d) in methanol. Acid-catalyzed nucleophilic substitution of 1 with nucleophiles gave 1,2,2-trisubstituted 3-oxo-2,3-dihydroindoles (3–6). Reduction of 1 with lithium aluminum hydride, followed by acidic workup yielded 4d and 2d, whereas the same reduction reaction of 1, followed by neutral workup gave l-methyl-2-phenyl-3-hydroxy-2,3-dihydroindole (15), together with 3. The reaction pathways of nucleophilic substitution and reduction of 1 were discussed.     

Synthesis and Some Transformations of 2-(3-Amino-1-Phenylpropyl)furan

A preparative method was developed for the synthesis of ethyl furfurylidenecyanoacetate. Its condensation with phenylmagnesium bromide gave ethyl α-cyano-β-(2-furyl)hydrocinnamate, the decarboxylation of which led to β-(2-furyl)hydrocinnamonitrile. Reduction of this nitrile with lithium aluminum hydride gave 2-(3-amino-1-phenylpropyl)furan. Some of its transformations were studied.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 517–521, April, 2005.     

Studies in stereochemistry—I Stereospecific routes to trans- anti- and cis- syn-Δ-dodecahydrophenanthrenes

Reduction of trans-1-oxo-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XI) by lithium tri-t-butoxyaluminohydride gave trans-1β-hydroxy-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XII) which on lithium—liquid ammonia reduction gave trans-anti-1β-hydroxy-7-oxo-Δ⁸⁽¹⁴⁾-dodecahydrophenanthrene (XIII). Reduction of cis-1-oxo-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XV) by sodium borohydride gave cis-1-hydroxy-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XVI) which on lithium—liquid ammonia reduction gave cis-syn-1-hydroxy-7-oxo-Δ⁸⁽¹⁴⁾-dodecahydrophenanthrene (XVII).     

Reduction of dichlorodiphenylstannane

Reduction of dichlorodiphenylstannane with lithium followed by treatment with methyl iodide gave methyltriphenylstannane, dimethyldiphenylstannane and 1,2‐dimethyldistannane. 1,2‐Dilithiodistannane and triphenylstannyllithium were intermediates of this reaction. Copyright © 2005 John Wiley & Sons, Ltd.     

Isoquinoline derivatives VI. Synthesis and pharmacological properties of 4,6,7-substituted 1(2)-arylalkyl-1,2,3,4-tetrahydroisoquinolines and their analogs

The condensation of 6,7-dimethoxy-1,2.3.4-tetrahydroisoquinoline (II) with diphenylacetyl and diphenylpropionyl chlorides gave the corresponding amides (III). Reduction of III with lithium aluminum hydride converted them to tertiary amines IV, which were characterized as their hydrochlorides. The condensation of equimolecular amounts of amines I with the acid chlorides of substituted phenylacetic and diphenylpropionic acids gave amides V. The reduction of amides V with lithium aluminum hydride gave secondary amines VI. The corresponding tetrahydroisoquinolines (VII) were obtained by the cyclization of amides V and subsequent reduction with lithium aluminum hydride, The condensation of 1-diphenylethyl-6,7-dimethoxy-l,2,3,4-tetrahydroisoquinoline with formalin gave VIII. The IR spectra of the synthesized compounds were examined. The effect of these compounds on the arterial blood pressure and the coronary blood flow was studied.See [1] for communication V.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1683–1687, December, 1971.     

Carboncarbon bond cleavage during lithium aluminum hydride reduction of a terminal propargyl alcohol

Reduction of dehydronerolidol with lithium aluminum hydride in the presence of sodium methoxide gave, in addition to the expected nerolidol, geranyl acetone. Labeling experiments established that the C-1 methyl of geranyl acetone is derived from one of the carbons of the acetylene.     

5,5,5-Trifluorolaevulic acid and some derived compounds

5,5,5-Trifluorolaevulic acid (II) has been prepared by the acidic hydrolysis of the Claisen condensation product (I) of ethyl trifluoroacetate and diethyl succinate. Dehydration of the acid (II) with phosphoric oxide gave 4-hydroxy-5,5,5-trifluoropent-3-enoic acid lactone (III). Reduction of either this lactone or the acid (II) with lithium aluminium hydride gave 5,5,5-trifluoropentane-1,4-diol (IV), from which 5,5,5-trifluoropenta-1,3-diene (VI) has been obtained by acetylation followed by pyrolysis.     

Synthesis and NMR-study of the 2,3,4,5-tetraethylsilole dianion [SiC₄Et₄]²⁻•2[Li]⁺

The previously unknown silole dianion [SiC(4)Et(4)]2??2[Li]+ (3) was prepared by the sonication of 1,1-dichloro-2,3,4,5-tetraethyl-1-silacyclopentadiene [Cl(2)SiC(4)Et(4), 2] with more than four equivalent of lithium in THF. 1H-, 13C-, and 29Si-NMR data of 3 are compared with those of the reported silole dianion [SiC(4)Ph(4)]2?. Trapping of 3 with trimethylchlorosilane gave 1,1-bis(trimethylsilyl)-2,3,4,5-tetraethyl-1-silacyclopentadiene [(Me(3)Si)(2)SiC(4)Et(4), 4] in high yield. The silole of 2 was synthesized in high yield in three steps by a modified procedure using Cp(2)ZrCl(2) via Cp(2)ZrC(4)Et(4) and 1,4-dibromo-1,2,3,4-tetraethyl-1,3-butadiene.     

The alkali metal reduction of pyrene structural and preparative aspects

Reduction of pyrene with alkali metals yields the corresponding dianion salts. The solvent, counterion and temperature must be carefully selected since side reactions such as protonation (e.g. in liquid ammonia) or cleavage of the etheral solvent occur readily. Moreover, the spectroscopic characterization of the dianion is complicated by rapid electron transfer processes. There is no experimental evidence for distorted dianion structures or for further reduction of pyrene toward a tetraanion. Knowledge of the ionic π-structures is essential for an understanding of reductive alkylation processes.     

Pentaatomie heteroaromatic cations. Note III . A Convenient Synthesis of Aldehydes from Carboxylic Acids via 2-Substituted 1,3-Benzoxathiolium Perchlorates

A convenient method for the preparation of aldehydes from the corresponding carboxylic acids is presented. By reaction of the carboxylic acids with o-mercaptophenol and perchloric acid in phosphorus oxychloride, the corresponding 2-substituted 1,3-benzoxathiolium perehlorates were obtained. Reduction of the salts with lithium aluminium hydride in dry ether gave 2-substituted 1,3-benzoxathioles, which, when hydrolyzed by mercuric chloride, gave the corresponding aldehydes. Twenty five aldehydes of different structure were obtained in good yields, by a fast and simple procedure.     

Synthesis of thiazole-containing benzo-crown ethers

A series of benzo-crown ethers containing the thiazole subcyclic moity have been synthesized. Reaction of 1,2-bis(thioamidomethyloxy)benzene 2 with ethyl bromopyruvate in ethanol provided 1,2-bis(thiazolyl)benzene 4 (80%) along with thiazole 5 (14%). Reduction of 4 with lithium aluminum hydride followed by mesylationbromination gave 7 . Similar treatment of 5 with lithium aluminum hydride followed by bromination resulted in 12 . Benzo-crown ethers 8, 9, 10 , and 13 were prepared from the reactions of 4-bromomethylthiazole derivatives 7 and 12 with catechol and resorcinol derivatives in the presence of potassium hydride.     

Reactivity of a Tetra(o‐tolyl)diborane(4) Dianion as a Diarylboryl Anion Equivalent

Lithium and magnesium salts of tetra(o‐tolyl)diborane(4) dianion, having B=B double bond character, were synthesized. It was clarified that the lithium salt of the dianion has a high‐lying HOMO and a narrow HOMO–LUMO gap, which were perturbed by dissociation of Li⁺ cation, as judged by UV/Vis spectroscopy and DFT calculations. The lithium salt of the dianion reacted as two equivalents of a diarylboryl anion with CH₂Cl₂ or S₈ to give boryl‐substituted products.     

The synthesis of diene and of vinyl copolymers containing predetermined quantities of polynuclear hydrocarbon or heterocyclic adducts—I. The formation and stability toward tetrahydrofuran of alkali metal salts of polynuclear hydrocarbons

The formation and stabilities of complexes formed in THF between various polynuclear hydrocarbons and excess sodium and lithium metal have been studied. Anthracene and acenaphthylene, which possess high electron affinities, form dianions with either metal whilst phenanthrene forms the dianion only with lithium. Both phenanthrene and naphthalene give solely radical ions on reaction with sodium; it is found that the formation of the naphthalene dianion with lithium is inversely dependent on the naphthalene concentration.The radical anions of all four polynuclear hydrocarbons are relatively stable to the THF solvent whereas the dianions react appreciably in a matter of days to form a variety of adducts and derivatives which have been isolated and identified by NMR spectroscopy.