Stable preservation of hemoglobin vesicles as a blood substitute

Long‐term preservation of hemoglobin (Hb) vesicles, the so‐called artificial red cell (ARC), in dry powder was studied. Carbonylhemoglobin (COHb) was encapsulated in the vesicle of 1,2‐bis(2,4‐octadecadienoyl)‐sn‐glycero‐3‐phosphocholine (DODPC) and the polymerizable membrane components were polymerized by γ‐ray irradiation. The obtained ARC suspension was then freeze‐dried in the presence of sucrose. The factors influencing the shelf‐life of the freeze‐dried ARC, such as sucrose concentration, moisture and storage temperature, were elucidated. After storage in the dry state for more than one year, the oxygen‐carrying capacity was recovered by rehydration of the freeze‐dried ARC with distilled water and substitution of the carbon monoxide ligand with oxygen. Copyright © 1999 John Wiley & Sons, Ltd.     

The essential oil of Artemisia scoparia from tajikistan is dominated by phenyldiacetylenes

The essential oil from the aerial parts of Artemisia scoparia was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. A total of 32 compounds were identified representing 98.0% of the total oil composition. A. scoparia oil was dominated by the diacetylenes 1-phenyl-2,4-pentadiyne (34.2%) and capillene (4.9%). Other major components were beta-pinene (21.3%), methyl eugenol (5.5%), alpha-pinene (5.4%), myrcene (5.2%), limonene (5.0%), and (E)-beta-ocimene (3.8%). The oil was tested for in-vitro cytotoxic activity against MCF-7 cells, but was inactive.     

Preparation and reactions of 1,3-diphosphacyclobutane-2,4-diyls that feature an amino substituent and/or a carbonyl group

The preparation and properties of a 1-amino-1,3-diphosphacyclobutane-2,4-diyl and a 1-benzoyl-1,3-diphosphacyclobutane-2,4-diyl, which can be regarded as functionalized cyclic biradical derivatives, were investigated. Hydrolysis of 1-diisopropylamino-3-methyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (7), which is formed by reaction of Mes*C[triple chemical bond]P (4; Mes*=2,4,6-tBu(3)C(6)H(2)) with lithium diisopropylamide and iodomethane, resulted in ring-opening of the 1,3-diphosphacyclobutane-2,4-diyl skeleton, as well as de-aromatization of one of the Mes* rings. 3-Oxo-1,3-diphosphapropene 8 and 7-phosphabicyclo[4.2.0]octa-1(8),2,4-triene 9 were the resultant products, and these were subsequently characterized. Isomerization and oxidation of 7 occurred in the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinoxy) to give the first example of a cyclic dimethylenephosphorane derivative, namely 3-oxo-1,3-diphospha-1,4-diene 10. 1-Benzoyl-3-tert-butyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (12) was isolated and characterized from the reaction of 4 with tert-butyllithium and benzoyl chloride. Compound 12 was subsequently heated and underwent rearrangement of the benzoyl group and ring-expansion to afford 1-oxo-1H-[1,3]diphosphole 13. Reaction of 4 with lithium diisopropylamide and benzoyl chloride afforded the 2H-[1,2,4]oxadiphosphinine 15, which was probably formed through the 1,3-diphosphacyclobutane-2,4-diyl intermediate 14. Thermolysis of 15 afforded 1-oxo-1H-[1,3]diphosphole 16 in an Arbuzov-type rearrangement.     

Theoretical study of reaction pathways to borazine

Four reaction pathways from diborane and ammonia to borazine, (HBNH)3, have been studied computationally at the density functional level (B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d)). The cycloaddition of H2BNH2 to 1,3-diaza-2,4-diborabuta-1,3-diene and subsequent elimination of two molecules of H2 was found to be the lowest-energy pathway to (HBNH)3. In the other pathways, the formation and conversion of the intermediates 1,3,5-triaza-2,4,6-triborahexatriene, cyclotriborazane, and 1,3,5-triaza-2,4,6-triborahexa-1,5-diene into (HBNH)3 were investigated. The formation of 1,3-diaza-2,4-diborabuta-1,3-diene and, subsequently, the formation and electrocyclization of 1,3,5-triaza-2,4,6-triborahexatriene and the cycloaddition of H2BNH2 to 1,3-diaza-2,4-diborabuta-1,3-diene are predicted to be the kinetically favored pathways to (HBNH)3 in the gas phase. At low concentrations of 1,3-diaza-2,4-diborabutene, high concentrations of H2BNH2, and a temperature of 298.15 K, the formation of the polyolefins H3BNH2(H2BNH2)nNHBH2 (n=1,2) is predicted to be competitive with the formation of 1,3-diaza-2,4-diborabuta-1,3-diene.     

Trace level determination of phenols as pentafluorobenzyl derivatives by gas chromatography-negative-ion chemical ionization mass spectrometry.

A method for the trace level determination of 11 phenols as pentafluorobenzyl (PFB) derivatives by gas chromatography-mass spectrometry (GC-MS) with negative-ion chemical ionization (NICI) is described. First, the conditions for the PFB derivatisation of phenols were optimized and were found to be reaction temperature 80 degrees C and reaction time 5 h. Second, the detection limits using selected ion monitoring (SIM) were compared between trimethylsilylated (TMS) derivatives in the electron ionization (EI) mode and PFB derivatives in the NICI mode. The responses for the PFB derivatives in the NICI mode were 3.3-61 times higher than those of the TMS derivatives in the EI mode. The instrumental detection limits using NICI-SIM ranged from 2.6 to 290 fg. This method was applied to the analysis of phenols in river water using solid-phase extraction. The recoveries of the phenols from a river water sample spiked with standards at 100 ng l-1 with 2-chlorophenol, 4-chloro-3-methylphenol and pentachlorophenol and at 1000 ng l-1 with phenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2-nitrophenol, 2,4,6-trichlorophenol and 4-nitrophenol were 81.2-106.3% (RSD 5.1-8.0%), except for 2-methyl-4,6-dinitrophenol and 2,4-dinitrophenol, for which the recoveries were 5.8 and 4.2%, respectively, because water contained in the acetone eluate interfered with the derivatisation of these compounds with two electrophilic nitro groups.     

Changing the ortho/para ratio in aromatic acylation reactions by changing reaction conditions: a mechanistic explanation from kinetic measurements

Kinetic measurements of the acylation of toluene (2a) and p-xylene (2b), side-chain deuterated toluene (2a-d(3)), as well as perdeuterated toluene (2a-d(8)) and p-xylene (2b-d(10)) with the aroyl triflate 1 in 1,2-dichloroethane reveal a strong dependence of the isotope effect on reaction conditions. In the presence of trifluoromethanesulfonic acid (HOTf), the second-order rate constants k(H)/k(D) observed are in the order of 1.75-1.94, whereas in the presence of 2,4,6-tri-tert-butylpyridine (4) rate constants k(H)/k(D) of 1.14-1.25 are found. The primary kinetic isotope effects observed correlate with the ortho/para ratio of the acylation of toluene. In the presence of 4 a relatively high percentage ( approximately 30%) of ortho product is obtained, whereas under acidic conditions the ratio is only 10%. The correlation between isotope effects and isomer distributions is obviously due to the rate of deprotonation of the corresponding sigma-complex intermediates. Assuming a bent structure for sigma-complexes, the conformation giving deprotonation is preferred in the para sigma-complex in comparison with ortho complex.     

Tautomerism of some amino aza-containing heterocycles

With the aim of checking potential amino/imino tautomerism in heterocyclic series, some uv/visible spectroscopic properties of 2-N-(2,4,6-trinitrophenyl)pyridine, 2-N-(2,4,6-trinitrophenyl)pyrimidine and of 2-N-(2,4,6-trinitrophenyl)thiazoleamine are reported and discussed. In dimethyl sulphoxide the imino tautomer of the thiazole derivatives is the more populated form, while in toluene the amino aromatic form predominates. The more populated tautomer of the pyridine and pyrimidine derivatives is the amino aromatic form in both polar and apolar solvents. For the thiazole derivatives the tautomeric equilibrium in toluene is shifted toward the imino form by adding small amounts of tetrabutylammonium bromide or of dimethyl sulphoxide. The position of the tautomeric equilibrium is quantitatively evaluated and discussed.     

Towards the bio-production of trans-carveol and carvone from limonene: induction after cell growth on limonene and toluene

Rhodococcus opacus PW4 cells were found to produce trans- and cis-carveol and/or carvone as result of limonene metabolism, depending on the type and concentration of the carbon source used for cell growth. In aqueous systems, cells grown on ethanol and toluene only produced trans-carveol, whilst cells grown on limonene and on toluene with a larger head-space available produced both trans-carveol and carvone. In biphasic systems, limonene was converted to trans- and cis-carveol as well as to carvone, regardless of the carbon source used, although carveol and carvone production rates were higher in toluene and limonene grown cells, respectively. A good and stable emulsion was obtained in a magnetically stirred two-phase reactor but both trans-carveol and carvone were produced at low rates: 0.08 and 0.02 nmol/min mg prot, respectively. No cis-carveol was formed. When (−)-carveol was added, carvone production increased 4.7 fold to 0.12 nmol/min mg prot. Using an aerated two-phase reactor, carvone production was enhanced even with cells grown on toluene. The highest trans- and cis-carveol and carvone production rates were attained with cells grown on limonene by continuously supplying limonene to the reactor through the air stream, carvone production reaching 0.58 nmol/min mg prot. The best trans-/cis-carveol ratio (2.26) was observed with cells grown on toluene when limonene was supplied in the gas phase. When 50 mM limonene was added initially, carvone was produced 27.9 and 141.4 times faster than trans-carveol with cells grown on toluene and limonene, respectively.     

Determination of phenol in landfill leachate by using microchip capillary electrophoresis with end-channel amperometric detection

Phenol, 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) were baseline separated by using a homemade microchip CE with an end-channel amperometric detector where a 50 microm Pt microdisk working electrode (WE) and a Pt cathode were integrated onto the microchip itself. Separation parameters such as injection time and voltage, pH of the buffer, online pretreatment condition for WE, reproducibility, and detection potential were investigated. Under the selected separation conditions, the linear ranges for phenol, 2,4-DCP, and 2,4,6-TCP were 2-200, 4-400, and 4-400 microM, respectively. The LODs were 0.4, 0.5, and 0.7 microM for phenol, 2,4-DCP, and 2,4,6-TCP, respectively (S/N = 3). The standard addition method was successfully applied to the analysis of landfill leachate samples and the concentration of phenol in the landfill leachate samples was measured to be 0.32 and 0.21 mM, respectively. The recoveries were in the range of 85-103% and corresponding RSDs were less than 5.5%.     

基于1-(4-己氧)苯和2,4,6-三苯基-1,3,5-三嗪功能化芴单元的聚合物蓝光材料的合成与表征

以聚(9,9-二己烷芴)(1)和聚(9,9-二(1-(4-己氧)苯)芴)(2)作为参照物,通过Suzuki偶联反应合成了侧链9位碳含有4-己氧基苯和2,4,6-三苯基-1,3,5-三嗪单元的芴共聚物3.聚合物1,2和3固体粉末的5%质量热损失温度分别是274,318和401℃,玻璃化转变温度分别是91,120和139℃.聚合物1,2和3在甲苯溶液中的最大吸收峰和荧光发射峰分别在380和435 nm.从聚合物1到聚合物3,薄膜的荧光发射最大半峰宽逐渐降低.大体积刚性吸电子2,4,6-三苯基-1,3,5-三嗪基团的引入,使聚合物1,2和3的热稳定性、蓝光发射的色纯度和光谱稳定性逐渐提高,不同工作电压驱动下聚合物3稳定的电致发光光谱进一步证明了这一点.聚合物1,2和3的最高占有轨道能级分别为-5.72,-5.95和-5.96eV,最低未占有轨道能级分别为-2.70,-2.39和-2.43 eV.聚合物1,2和3的三线态能级分别为2.82,2.81和2.97 eV.聚合物1,2和3的单线态-三线态能级差分别是0.32,0.32和0.15 eV.4-己氧基苯的引入使聚合物的能隙变宽,而吸电子的2,4,6-三苯基-1,3,5-三嗪的引入使聚合物单线态-三线态能级差依次减少.聚合物1,2和3粉末均易于形成非晶薄膜.聚合物3粉末的有序性介于聚合物1和2之间,聚合物2侧链的烷氧基苯有助于提高固体粉末有序形态的多样化.综合结果表明,侧链含有刚性4-己氧基苯和2,4,6-三苯基-1,3,5-三嗪基团的无规共聚物3具有更佳的综合光电性质.     

The determination of nitroaromatics and nitramines in ground and drinking water by wide-bore capillary gas chromatography

A method has been developed to determine the concentration of nitroaromatics and nitramines in drinking water at levels below those previously achieved by gas chromatography. The nitroaromatics and nitramines are extracted from water using toluene and isoamyl acetate, respectively. The extracts are analyzed via a gas chromatograph equipped with a DB-1301 widebore fused-silica capillary column and an electron capture detector. Method detection limits of 0.003 micrograms/L for 2,6-dinitrotoluene (2,6-DNT), 0.04 micrograms/L for 2,4-dinitrotoluene (2,4-DNT), 0.06 micrograms/L for 2,4,6-trinitrotoluene (TNT), 0.3 micrograms/L for cyclotrimethylenetrinitramine (RDX), and 6.0 micrograms/L for cyclotetramethylenetetranitramine (HMX) have been obtained using this method.     

Theoretical study of reaction mechanisms of OH radical with toluene 1,2-epoxide/2-methyloxepin

In this study, the reaction mechanism of toluene 1,2-epoxide/2-methyloxepin with OH radical was studied by means of quantum chemical computations performed using B3LYP/6-31G(d,p), B3LYP/6-311G(2df,2p), and BHandHLYP/6-31G(d,p) methods. Ground state, intermediate, and transition states were determined. The results indicated that the 2-methyloxepin, A, isomer is more stable, by 2.4 kcal/mol, than toluene 1,2-epoxide, B. Two reaction pathways were studied, RP-A and RP-B, corresponding to the reaction of OH with toluene 1,2-epoxide and 2-methyloxepin, respectively. The localization of a pre-reactive complex for RP-A is crucial for the accurate estimation of the rate constant, k=1.0x10(-10) cm3 molecule(-1) s(-1), which is in good agreement with that determined experimentally, whereas for RP-B the rate constant is 1.3x10(-14) cm3 molecule(-1) s(-1). Under atmospheric conditions, both pathways yield 6-oxohepta-2,4-dienal as a main product, and from the energetic and kinetic results it was found that RP-A is the preferred pathway. The study of the oxide/oxepin mechanism is relevant because, aside from its relatively high concentration in the troposphere, this compound has carcinogenic and mutagenic properties.     

Composition and chemical variability of leaf oil of Myrtus communis from north-eastern Algeria

The chemical composition of 27 oil samples of Myrtus communis isolated from leaves collected in three locations in north-eastern Algeria was investigated by GC(RI) and 13C NMR spectroscopy. Yields ranged between 0.2-1.2% (w/w). The chemical composition of the oils was largely dominated by monoterpene hydrocarbons, with alpha-pinene (40.5-64.0%), 1,8-cineole (10.9-29.1%) and limonene (6.7-8.2%) being the major compounds. In all the samples, 3,3,5,5,8,8-hexamethyl-7-oxabicyclo[4.3.0]non-1(6)-ene-2,4-dione was identified (0.8-1.5%). The composition is similar to that reported for myrtle oils from Corsica, Sardinia and Tunisia, but differed from that of Moroccan and Spanish myrtle oils.     

New method for the annelation of a pyridine ring on derivatives of imidazole and benzimidazole

The interaction of (Z)-1,3-diaryl-4-bromo-2-buten-1-ones with 1-substituted (benz)imidazoles in benzene gave (Z)-1-R-3-(2,4-diaryl-4-oxo-2-butenyl)-1H-imidazolium bromides and (Z)-1-R-3-(2,4-diaryl-4-oxo-2-butenyl)-1H-benzimidazolium bromides which readily cyclize in the presence of base to form derivatives of 7,9-diarylpyrido[1,2-a]benzimidazole and 6,8-diarylpyrimidazo[1,2-a]pyridine. The effects of the nature of substituents in the benzene ring of the diarylbutenones and the substituent at N(1) in the (benz)imidazoles on the alkylation and cyclization reactions has been studied. The optimum conditions for the synthesis of the 5-R-4-hydroxy-2,4-diphenyl-4,5-dihydro-1H-pyrido[1,2-a]benz-imidazol-10-ium, 5-R-2,4-diaryl-4-hydroxy-4,5-dihydro-3H-pyrido[1,2-a]benzimidazol-10-ium, and 5-R-2,4-diaryl-5H-pyrido[1,2-a]benzimidazol-10-ium have been found.     

Microbial synthesis and characterization of polyhydroxyalkanoates with fluorinated phenoxy side groups from Pseudomonas putida

Microbial poly(3-hydroxyalkanoates) (PHAs) with fluorinated phenoxy side groups were produced by Pseudomonas putida when fluorophenoxyalkanoic acids were used as carbon sources. 11-(2-Fluorophenoxy)undecanoic acid (2FPUDA), 11-(3-fluorophenoxy)undecanoic acid (3FPUDA), 11-(4-fluorophenoxy)undecanoic acid (4FPUDA), 11-(2,4-difluorophenoxy)undecanoic acid (2,4DFPUDA), 11-(2,4,6-trifluorophenoxy)undecanoic acid (2,4,6TFPUDA), and 11-(2,3,4,5,6-pentaflurophenoxy)undecanoic acid (2,3,4,5,6PFPUDA) were used as carbon sources in the present study. When cells were grown with 2,4DFPUDA, the production of homo poly(3-hydroxy-5-(2,4-difluorophenoxy)pentanoate) was confirmed by NMR and GC/MS analyses. Fluorine atoms inserted into the side chain of the PHA dramatically affected its physical properties. In marked contrast to medium chain length (MCL) PHA, this fluorinated PHA was opaque, cream colored, and possessed greater crystallinity and a higher melting point (∼100 °C) than did the other MCL PHAs. Surface contact angle evaluation revealed that the PHA with two fluorine atoms possessed water-shedding properties. The number of substituted fluorine atoms in the carbon source affected cell growth and difluorine-substituted phenoxyalkanoic acids reduced cell growth, and polymer production compared to non-substituted phenoxyalkanoic acids. No polymeric materials were obtained using either 2,4,6TFPUDA or 2,3,4,5,6PFPUDA.     

s-Triazine derivatives. 4. Some peculiarities of the reactions of dicarbethoxymethylenetriazine derivatives

2- (Carbethoxycyanomethylene)-4,6-dimethoxy-1,2-dihydro-s-triazine reacts with hydrochloric acid to give 2-(carbethoxycyanomethylene)-4,6-dioxohexahydro-s-triazine (I) and with boric acid to give a mixture of the first compound with 2-(carbethoxy-cyanomethylene)-4-oxo-6-methoxy-1,2,3,4-tetrahydro-s-triazine. The products of the reaction of 2,4,6-tris(dicarbethoxymethylene)hexahydro-s-triazine with aniline are 2-(dicarbanilidomethylene)-4-methyl-6-phenylamino-1,2-dihydro-s-triazine (43%), N,N-diphenylurea (18%), and malonic acid dianilide (18%). In aqueous dioxane in the presence of A1₂O₃ this compound is converted to 2,4-bis(dicarbethoxy-methylene)-6-methyl-1,2,3,4-tetrahydro-s-triazine, which reacts with liquid ammonia to give 2-(dicarbethoxymethyl)-4-amino-6-methyl-s-triazine.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 684–687, May, 1981.     

Ruthenium-catalyzed cyclization of alkyne-epoxide functionalities through alternation of the substituent and structural skeleton of epoxides

Treatment of 1-(o-ethynylphenyl)-2-alkyl-2-aryl epoxides with TpRuPPh(3)(CH(3)CN)(2)PF(6) catalyst (10 mol %) in hot toluene (100 degrees C, 12 h) led to an atypical cyclization and gave 1-aryl-2-alkyl-1H-indene derivatives and carbon monoxide efficiently. The cyclization of 1-cis-enynyl-2-alkyl epoxides with this catalyst in hot toluene (10 mol %, 100 degrees C, 12 h) gave 2,5-disubstituted phenols in 45-72% yields. Under the same conditions, 1-cis-enynyl- 2,2-dialkyl epoxides and 1-cis-enynyl- 2-alkyl-2-aryl epoxides gave the corresponding 6,6-disubstituted cyclohexa-2,4-dien-1-ones in good yields (85-91%). Mechanisms for these new cyclization reactions are proposed on the basis of trapping experiments and isotope labeling experiments. The formation of 1H-indene products likely involves ruthenium-acyl intermediates whereas cyclohexa-2,4-dien-1-ones are thought to derive from ruthenium-ketene intermediates.     

Experimental and quantum chemical studies of the electronic absorption spectra of pyrimidine derivatives

The electronic absorption spectra of different pyrimidine derivatives have been measured experimentally and calculated theoretically by the PPP and CNDO/S methods. These pyrimidine derivatives are: 4,6-dichloro-pyrimidine (I), 4,6-dichloro, 5-amino-pyrimidine (II), 2,4,6-trichloro-pyrimidine (III), 4,6-dihxdroxy-pyrimidine (IV), 4,6-dihxdroxy-5-nitro-pyrimidine (V), 2,4-diamino-pyrimidine (VI), 2,4-diamino-6-hydroxy-pyrimidine (VII), 2,4-dihydroxy-5-carboxy-pyrimidine (VIII), 2,4-dimethyl-6-hydroxy-pyrimidine (IX), 5-nitro-uracil (X), and orotic acid (XI). The observed electronic spectral shifts are quantitatively analyzed in relation to different solute–solvent interaction mechanisms. The effects of solvent polarity and hydrogen bonding on the spectra are discussed in the light of theoretical predictions. This comparative analysis provides a reasonable picture of the solvent effects on the absorption spectral properties of pyrimidine nucleobases.     

Gold-Catalyzed Regiospecific Annulation of Unsymmetrically Substituted 1,5-Diynes for the Precise Synthesis of Bispentalenes

Precise control of the selectivity in organic synthesis is important to access the desired molecules. We demonstrate a regiospecific annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene derivatives for a geometry-controlled synthesis of linear bispentalenes, which is one of the promising structures for material science. A gold-catalyzed annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene could produce two isomeric pentalenes, but both electronic and steric effects on the aromatics at the terminal position of the alkyne prove to be crucial for the selectivity; especially a regiospecific annulation was achieved with sterically blocked substituents; namely, 2,4,6-trimetyl benzene or 2,4-dimethyl benzene. This approach enables the geometrically controlled synthesis of linear bispentalenes from 1,2,4,5-tetraethynylbenzene or 2,3,6,7-tetraethynylnaphthalene. Moreover, the annulation of a series of tetraynes with a different substitution pattern regioselectively provided the bispentalene scaffolds. A computational study revealed that this is the result of a kinetic control induced by the bulky NHC ligands.     

Generation and conversion of the transient 1,1-bis(trimethylsilyl)-2-( 2,4,6-triisopropylphenyl)-silene

Treatment of 2,4,6-triisopropylbenzaldehyde with tris(trimethylsilyl)silylmagnesium bromide (2) gives 2,4,6-triisopropylphenyl-tris(trimethylsilyl)silyl-methanol (3) in approximately 70% yield and E-3,4-bis(2,4,6-triisopropylphenyl)-1,1,2,2-tetrakis(trimethylsilyl)-1,2-disilacyclobutane (5) (15%). 5 is the [2 + 2] head-to-head cyclodimer of the transient 1,1-bis(trimethylsilyl)-2-(2,4,6-triisopropylphenyl)silene (4), formed by trimethylsilanolate elimination according to a Peterson mechanism from the magnesium alkoxide, derived from the alcohol 3. Deprotonation of 3 with McLi at low temperature in ether produces a complex mixture of products, the main constituents being the silene dimer 5 (10%) and bis(trimethylsilyl)-2,4,6-triisopropylbenzyl-trimethylsiloxysilane (10) (60%), which is formed by readdition of the eliminated lithiumtrimethylsilanolate at the Si=C bond of 4. The deprotonation of 3 with McMgBr or PhMgBr (activated by LiBr) in THF at room temperature results in the formation of the polysilane (Me₃Si)₃SiSi(SiMe₃)₂CH₂(2,4,6-C₆H₂iPr₃) (13). Its generation indicates that there exists an equilibrium between the magnesium alkoxide derived from the alcohol 3 on one side, and the magnesium silanide 2 and 2,4,6-triisopropylbenzaldehyde on the other side. Possible pathways of the formation of the compounds mentioned, as well as of further by-products, are discussed. The 1,2-disilacyclobutane 5 is characterized by an X-ray crystal structure analysis.