Synthese und chemie von 4R-silacyclohexa-2,5-dienen und 4R-silacyclohexa-2,4-dienen

The 1(Z),4(Z)-1,5-dilithium-3R-3-methoxypenta-1,4-dienes, available by cleavage of 1,1-di-n-butyl-4R-4-methoxy-1-stannacyclohexane-2,5-dienes with n-BuLi in ether, react with dichlorosilanes (R′R″ SiCl₂; R′, R″ = H, alkyl, aryl, alkoxy) to give 1R′,1R″,4R-4-methoxy-1-silacyclohexa-2,5-dienes.Claevage of the ether group with BBr₃, BCl₃ or PCl₃ gives 6-chloro(bromo)-1-silacyclohexa-2,4-dienes or 1,5-dichloro-1-silacyclohexane-2,4-dienes, respectively.Ether cleavage of 4R-4-methoxy-1-silacyclohexa-2,5-dienes with sodium results in the formation of 4R-1-silacyclohexadienyl anions, which can be hydrolyzed to give 1-silacyclohexa-2,4-dienes which reach further with trichloromethylsilane to give 6-trimethylsilyl-1-silacyclohexa-2,4-dienes.Phase transfer-catalyzed conversion of 1-chlorosilacyclohexadienes into the fluoro derivatives as well as further substitution reactions of 1-chlorosilacyclohexadienes are described.The ¹H NMR, ¹³C NMR, IR and mass spectra of the silacyclohexadienes are discussed.     

Synthesis and structure of 1-metallacyclopent-3-yne complexes of group 4 metals

Five-membered metallacyclic alkyne complexes of titanium and hafnium, 1,1-bis(cyclopentadienyl)-1-titanacyclopent-3-yne (2) and trans-1,1-bis(cyclopentadienyl)-2,5-trimethylsilyl-1-hafnacyclopent-3-yne (6), were synthesized and structurally characterized. The structural analysis of titanium complex 2 implied a larger contribution of an η⁴-π,π-coordinated structure. The hafnium compound 6 has a similar structure to the corresponding zirconium analogue (1a), although slight differences in the bond lengths and angles were observed. A novel 1-zirconacyclopent-3-yne complex, 1,1-bis(methylcyclopentadienyl)-2,5-bis(trimethylsilyl)-1-zirconacyclopent-3-yne (5), was also prepared and the structure of the trans-isomer was determined.     

Preparation of 1,1-disubstituted silacyclopentadienes

Several new 1,1-disubstituted siloles containing substituents on the ring carbon atoms have been synthesized. The new siloles: 1,1-dihydrido-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (5), 1,1-dihydrido-2,5-dimethyl-3,4-diphenylsilole (6), 1,1-dimethoxy-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (7), 1,1-bis(4-methoxyphenyl)-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (8), 1,1-dipropoxy-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (9), and 1,1-dibromo-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (13) were prepared from reactions originating from the previously reported, 1,1-bis(diethylamino)-2,5-bis(trimethylsilyl)-3,4-diphenylsilole (1) or 1,1-bis(diethylamino)-2,5-dimethyl-3,4-diphenylsilole (2). In addition, three other new organosilane byproducts were observed and isolated during the current study, bis(4-methoxyphenyl)bis(phenylethynyl)silane (11), bis(4-methoxyphenyl)di(propoxy)silane (12) and 1-bromo-4-bromodi(methoxy)silyl-1,4-bis(trimethylsilyl)-3,4-diphenyl-1,3-butadiene (14). Compounds 13 and 14 were characterized by X-ray crystallography and 14 is the first 1,1-dibromosilole whose solid state structure has been determined.     

The reductive dimerization of some 1,3-dienes and of 1,3,5-cycloheptatriene in the presence of trimethylchlorosilane: a DFT investigation

Treatment of 1,3-dienes and 1,3,5-cycloheptatriene by chlorotrimethylsilane in the presence of wire of lithium led mainly to reductive dimerization with formation of bis(allylsilane) derivatives. Bis-silyl compounds obtained: from 1,3-butadiene, 1,8-bis(trimethylsilyl)-2,6-octadiene (70%); from isoprene, (Z,Z)-2,7-dimethyl-1,8-bis(trimethylsilyl)-2,6-octadiene (44%) and 2,6-dimethyl-1,8-bis(trimethylsilyl)-2,6-octadiene (19%); from butadiene-isoprene mixture (1:1), 3-methyl-1,8-bis(trimethylsilyl)-2,6-octadiene (55%); from 2,3-dimethylbutadiene, (E,E)-2,3,6,7-tetramethyl-1,8-bis(trimethylsilyl)-2,6-octadiene (36%), from 1,3-cyclohexadiene, 4,4′-bis(trimethylsilyl)-bicyclohexyl-2,2′-diene (48%); from 1,3,5-cycloheptatriene, 1,1′-bi[(S^∗,S^∗)-6-(trimethylsilyl)cyclohepta-2,4-dien-1-yl] (53%). The structure of the various intermediates (radical anion, dianion, silylated radical, silylated anion) has been established by calculations at the B3LYP/6-311++G(d,p) level of theory with zero-point energy correction. These results are in accordance with a pathway including the formation of a radical anion, its silylation furnishing to a γ-silylated allylic radical followed by a dimerization reaction in the head to head manner.     

Intramolecularly donor-stabilized silenes: Part 5. Generation and conversion of 1-[2,6-bis(alkoxymethyl)phenyl]- and 1-(8-alkoxynaphthyl)-1,2,2-tris(trimethylsilyl)silenes

1-(8-Methoxy-1-naphthyl)-1,2,2-tris(trimethylsilyl)silene (10) and the 1-[2,6-bis(alkoxymethyl)phenyl]-1,2,2-tris(trimethylsilyl)silenes (12a-d) were generated by the reaction of (dichloromethyl)tris(trimethylsilyl)silane (1) with two molar equivalents of 8-methoxy-1-naphthyllithium or 2,6-bis(alkoxymethyl)phenyllithium (8a-d), respectively, but proved to be unstable. 10 was trapped with excess of the applied naphthyllithium reagent to give 1,1-bis(8-methoxy-1-naphthyl)-1-[bis(trimethylsilyl)methyl]-2,2,2-trimethyldisilane (11); and 12a-d underwent spontaneous conversions and formed two types of substituted 2-oxa-1-silaindane derivatives (13a,b and 14b-d). Whereas silenes with an intramolecular amine coordination are thermally stable compounds which can be isolated, the intramolecular coordination of an ether group to the electrophilic silene silicon atom does not provide a comparable stabilization to the SiC system and the respective derivatives generated were converted into resultant products.     

Synthese und reaktionen von 1-germcyclohexa-2,4-dienen und 1-germacyclohexa-2,4-dien-eisentricarbonylen

1,1-Diakyl(aryl)4-alkyl(aryl)-4-methoxy-1-germacyclohexa-2,5-dienes undergo ether cleavage with sodium in n-pentane or liquid ammonia. Hydrolysis of the resulting sodium salts yields the 1,1-dialkyl(aryl)-4-alkyl(aryl)-1-germacyclohexa-2,4-dienes. Reduction of 1-chloro-4-methoxy-1-germacyclohexa-2,5-dienes with LiAlH₄ can be directed to give the 1H-1-germacyclohexa-2,4-dienes with ether cleavage.The 1H-1-germacyclohexadienes are chlorinated by PCl₅ and brominated by N-bromosuccinimide to the 1-chloro- or 1-bromo-1-germacyclohexa-2,4-dienes, respectively. 1,1-Diethyl-4-phenyl-4-methoxy-1-germacyclohexa-2,5-diene reacts with PCl₃ with ether cleavage and formation of the 6-chloro-1-germacyclohexa-2,4-diene. Ether cleavage is also possible with BCl₃, the 1-phenyl-1-chloro-4R-4-methoxy-1-germacyclohexa-2,5-dienes are transformed into the 1-phenyl-1,6-dichloro-4R-1-germacyclohexa-2,4-dienes.The Fe(CO)₃ complexes of 1,1-dialkyl(aryl)-1-germacyclohexa-2,4-dienes were synthesized.     

Synthesis of stereo-defined 1,1,4,4-tetrahalo- and 1,1,4,4-mixed-tetrahalo-1,3-butadienes

Stereo-defined 1,1,4,4-tetrahalo- and 1,1,4,4-mixed-tetrahalo-1,3-butadienes were obtained in excellent yields via desilylation-halogenation of their corresponding 1,4-bis(trimethylsilyl)-1,4-dihalo-1,3-dienes, which could be readily prepared from the zirconocene-mediated high-yield and high-regioselective cyclo-dimerization of 1-trimethylsilyl-1-alkynes followed by halogenation. These poly-functionalized gem-dihalodienes are potentially useful building blocks.     

Iron pentacarbonyl assisted photochemical route to 2,5- and 2,6-divinyl-substituted 1,4-benzoquinones from 1-ene-3-ynes

Photochemical reaction between the enynes, (Z)-1-methoxybut-1-ene-3-yne, 1 or isopropenyl acetylene, 2 with CO in presence of Fe(CO)₅ yields the 2,6- and 2,5-divinyl-substituted 1,4-benzoquinones: 2,6-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (3, 42%), 2,5-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (4, 31.5%), [{η²,η²:2,6-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (5, 45%), and {η²,η²:2,5-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (6, 65%).     

Synthesis of new imines and amines containing organosilicon groups

The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me₃Si)₃CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (2). The new aldehyde (1) reacts with variety of amines in ethanol to afford the corresponding imines (3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines (3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH₄. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH₄ was used as a reducing agent in THF.     

New method of synthesis of 1,1-bis(trialkylsilyl)- and bis(trialkylgermyl)germacyclopenta-2,4-dienes

The reactions of 1,1-dichloro-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene (1), magnesium, and R₃ECl (E = Si, Ge) under mild conditions (20 °C, THF) gave 1,1-bis(trimethylsilyl)-2,3,4,5-tetraphenyl-1-germacyclopenta-2,-4-diene (2a) and 1,1-bis(triethylgermyl)-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene (2b) respectively. The reaction is versatile and applies to the compounds R₃ECl (E = Si, Ge) that do not react with magnesium.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2234–2236, October, 2004.     

Synthesis of 5-Aryl-1,4-naphthoquinone and 1-Aryl-9,10-anthraquinone Derivatives by Cycloaddition of 1-(Dimethoxyphenyl)-3-trimethylsiloxy-1,3-butadienes to 1,4-Benzoquinones and 1,4-Naphthoquinones

The Diels-Alder reaction of new 1-(3,4-dimethoxyphenyl)- or 1-(2,4-dimethoxyphenyl)-2-R-3-trimethylsiloxy-1,3-butadienes with 2,5- and 2,6-dibromo-, and 2-bromo-6-methyl-1,4-benzoquinones regioselectively yields substituted 7-hydroxy-5-(dimethoxyphenyl)-1,4-naphthoquinones. By cycloaddition of the siloxydienes to naphthoquinone, bromonaphthoquinone, and juglone the corresponding substituted 3-hydroxy-1-(dimethoxyphenyl)-9,10-anthraquinones or their 4,4a-dihydro or 1,1a,4,4a-tetrahydro derivatives were obtained.     

Synthesis of 3 or 3,3′-substituted BINOL ligands and their application in the asymmetric addition of diethylzinc to aromatic aldehydes

Three new substituted BINOL ligands (R)-3-[4,6-bis(dimethylamino)-1,3,5-triazin-2-yl]-1,1′-bi-2-naphthol (R)-1, (R)-3,3′-bis[4,6-bis(dimethylamino)-1,3,5-triazin-2-yl]-1,1′-bi-2-naphthol (R)-2 and 2,4-bis(2,2′-dihydroxy-1,1′-binaphthalen-3-yl)-6-(p-tolyl)-1,3,5-triazine (R,R)-3 have been obtained by directed ortho-lithiation or Suzuki cross-coupling process. Ligand (R)-1 shows improved catalytic properties for the asymmetric diethylzinc addition to aromatic aldehydes.     

Enantioselective synthesis of 1-nitrotricyclo[5,2,2,02,6]undeca-3,8-dienes via tandem consecutive asymmetric Diels–Alder reaction–Cope rearrangement

The 1-glyco-2-nitrocyclohexa-2,4-dienes 1a and 5a react with cyclopentadiene to yield, almost exclusively, the 10-glyco-1-nitrotricyclo[5,2,2,0^2,6]undeca-3,8-dienes 4a and 8a. Formation of these products is explained as the result of a tandem consecutive asymmetric Diels–Alder reaction–Cope rearrangement. Periodate oxidation of deprotected sugar side-chains, followed by sodium borohydride reduction yielded enantiomerically pure 10-formyl- and 10-hydroxymethyl-1-nitrotricyclo[5,2,2,0^2,6]undeca-3,8-dienes. Structures have been determined by X-ray crystallographic and spectroscopic analyses, and chemical correlation.     

Synthesis of carba-analogues of myoseverin by regioselective cross-coupling reactions of 2,6-dichloro-9-isopropylpurine

A series of 9-isopropylpurine derivatives bearing 4-methoxyphenyl, 4-methoxybenzyl, (4-methoxyphenyl)ethynyl and 2-(4-methoxyphenyl)ethyl groups in positions 2 and 6 were prepared as carba-analogues of antimitotic myoseverin. Cross-coupling reactions of 2,6-dichloro-9-isopropylpurine (1) with one equivalent of (4-methoxyphenyl)boronic acid or (4-methoxybenzyl)zinc chloride gave regioselectively the 6-substituted 2-chloropurines which were used for another cross-coupling reaction with a second equivalent of the organometallic reagent. The Sonogashira reaction of 1 with 4-(methoxyphenyl)ethyne gave 2,6-bis[(4-methoxyphenyl)ethynyl]-9-isopropylpurine that was hydrogenated to 2,6-bis[2-(4-methoxyphenyl)ethyl]-9-isopropylpurine. Regioselectivity of the couplings was proved by means of ¹H-¹⁵N HMBC experiments. 2,6-Bis[(4-methoxyphenyl)ethynyl]-9-isopropylpurine showed considerable cytostatic activity, while the other compounds were inactive.     

Synthesis of new heterocycles by oxidation of functionalized cyclic derivatives of bis(2-chlorovinyl) sulfide and selenide

Oxidation of 4-substituted 2,6-bis[(E)-chloromethylidene]thiomorpholine with hydrogen peroxide in a mixture of chloroform with acetic acid afforded the corresponding 4-R-2,6-bis[(E)-chloromethylidene]-thiomorpholine 1-oxide. The results of oxidation of bis[(E)-chloromethylidene]-1,4-dichalcogenanes under analogous conditions depended on the chalcogen nature and its position in the ring. The reaction of 2,6-bis[(E)-chloromethylidene]-1,4-dithiane gave 2,6-bis[(E)-chloromethylidene]-1,4-dithiane-1,1,4,4-tetraone, whereas 3,5-bis[(E)-chloromethylidene]-1,4-thiaselenane-1,1-dione was unexpectedly obtained from 3,5-bis[(E)-chloromethylidene]-1,4-thiaselenane. 2,6-Bis[(E)-chloromethylidene]-1,4-thiaselenane and 2,6-bis[(E)-chloromethylidene]-1,4-diselenane decomposed under the oxidation conditions.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-trimethylsilyl-substituded anililes

N-Metallation of bromoanilines with ethylmagnesium bromide followed by a reaction with trimethylchlorosilane provided N-mono and N-bis(trimethylsilyl)bromoanilines depending on the structure of substrate. The metallation of bissilylated bromoanilines with butyllithium permitted the introduction of a trimethylsilyl substituent in the aromatic ring. Previously unknown 2-bromo-N,N-bis(trimethylsilyl)aniline, 2,6-dibromo-N-trimethylsilylaniline, 2,6-dibromo-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilylaniline, 2-bromo-6-trimethylsilyl-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilyl-N-trimethylsilylaniline, 2,4,6-tribromo-N-trimethylsilylaniline, and 2,4,6-tribromo-N,N-bis(trimethylsilyl)aniline were prepared. The structures of the compounds obtained were established by the chromato-mass spectrometry and ¹H, ¹³C, and ²⁹Si NMR spectroscopy.     

Synthesis of N-vinyl 2,2-bisphosphonoaziridines from 1,1-bisphosphono-2-aza-1,3-dienes

N-Vinyl 2,2-bisphosphonoaziridines are formed by treatment of 1,1-bisphosphono-2-aza-1,3-dienes with diazomethane. Depending on the substituents at the 4-position of the 1,1-bisphosphono-2-aza-1,3-dienes, exclusively 1-(ethenylamino)-2-phosphonoethenylphosphonates or mixtures of 1-(ethenylamino)-2-phosphonoethenylphosphonates and 2-imino-2-phosphonoethylphosphonates are obtained as side products.     

Manganese(III)-mediated intermolecular cyclization reactions of alkenes and active methylene compounds

The reactions of 1,1-diphenylethene, 1,1-bis(4-chlorophenyl)ethene, 1,1-bis(4-methylphenyl)ethene, and 1,1-bis(4-methoxyphenyl)ethene with 3,5-diacetyl-2,6-heptanedione in the presence of manganese(III) acetate in acetic acid at 80° yielded 4,6-diacetyl-8,8-diaryl-1,3-dimethyl-2,9-dioxabicyclo[4.3.0]non-3-enes (41-48%), 5-acetyl-2,2-diaryl-6-methyl-2,3-dihydrobenzo[b]furans (20–21%), 3-acetyl-5,5-diaryl-2-methyl-4,5-dihydrofurans (5–10%), and benzophenones (3–7%). Similarly, the reactions of 1,1-diarylethenes with dimethyl 2,4-diacetyl-1,5-pentanedioate or diethyl 2,4-diacetyl-1,5-pentanedioate gave the corresponding 4,6-bis(alkoxycarbonyl)-8,8-diaryl-1,3-dimethyl-2,9-dioxabicyclo[4.3.0]non-3-enes in moderate yields.     

Reaction of azulene with 1,2-bis[4-(dimethylamino)phenyl]-1,2-ethanediol in a mixed solvent of methanol and acetonitrile in the presence of hydrochloric acid: a facile one-pot synthesis and properties of new triarylethylenes possessing an azulen-1-yl group

Reaction of azulene (1) with 1,2-bis[4-(dimethylamino)phenyl]-1,2-ethanediol (2) in a mixed solvent of methanol and acetonitrile in the presence of 36% hydrochloric acid at 60 °C for 3 h gives 2-(azulen-1-yl)-1,1-bis[4-(dimethylamino)phenyl]ethylene (3) (8% yield), 1-(azulen-1-yl)-(E)-1,2-bis[4-(dimethylamino)phenyl]ethylene (4) (28% yield), and 1,3-bis{2,2-bis[4-(dimethylamino)phenyl]ethenyl}azulene (5) (9% yield). Besides the above products, this reaction affords 1,1-di(azulen-1-yl)-2,2-bis[4-(dimethylamino)phenyl]ethane (6) (15% yield), a meso form (1R,2S)-1,2-di(azulen-1-yl)-1,2-bis[4-(dimethylamino)phenyl]ethane (7) (6% yield), and the two enantiomeric forms (1R,2R)- and (1S,2S)-1,2-di(azulen-1-yl)-1,2-bis[4-(dimethylamino)phenyl]ethanes (8) (6% yield). Furthermore, addition reaction of 3 with 1 under the same reaction conditions as the above provides 6, in 46% yield, which upon oxidation with DDQ (=2,3-dichloro-5,6-dicyano-1,4-benzoquinone) in dichloromethane at 25 °C for 24 h yields 1,1-di(azulen-1-yl)-2,2-bis[4-(dimethylamino)phenyl]ethylene (9) in 48% yield. Interestingly, reaction of 1,1-bis[4-(dimethylamino)phenyl]-2-(3-guaiazulenyl)ethylene (11) with 1 in a mixed solvent of methanol and acetonitrile in the presence of 36% hydrochloric acid at 60 °C for 3 h gives guaiazulene (10) and 3, owing to the replacement of a guaiazulen-3-yl group by an azulen-1-yl group, in 91 and 46% yields together with 5 (19% yield) and 6 (13% yield). Similarly, reactions of 2-(3-guaiazulenyl)-1,1-bis(4-methoxyphenyl)ethylene (12) and 1,1-bis{4-[2-(dimethylamino)ethoxy]phenyl}-2-(3-guaiazulenyl)ethylene (13) with 1 under the same reaction conditions as the above provide 10, 2-(azulen-1-yl)-1,1-bis(4-methoxyphenyl)ethylene (16), and 1,3-bis[2,2-bis(4-methoxyphenyl)ethenyl]azulene (17) (93, 34, and 19% yields) from 12 and 10 and 2-(azulen-1-yl)-1,1-bis{4-[2-(dimethylamino)ethoxy]phenyl}ethylene (18) (97 and 58% yields) from 13.     

Synthesis and solid-state structure of thermally stable linear bi-pyrazoles

The long and rigid bi-pyrazolyl-based ligands 2,6-bis[4-(1H-pyrazol-4-yl)phenyl]pyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetrone, L1, and 2,5-bis[4-(1H-pyrazol-4-yl)phenyl]thiazolo[5,4-d]thiazole, L2, were isolated in pure form, with satisfying yields, as very insoluble polycrystalline materials. Their thermal behavior was investigated by coupling thermal analyses and variable-temperature X-ray powder diffraction measurements. Their crystal structures were unraveled from powder diffraction data by a rather unconventional structure determination approach, without the a priori knowledge of the unit cell parameters. Inline with shorter analogues, successfully employed in the formation of porous MOFs with intriguing functional properties, L1 and L2 are promising to construct higher-porosity materials, potentially capable of hosting nano-sized guests.