Polar bonds in π-complexes. Preparation and crystal structures of cyclopentadienylcarbonyl iron(II) and ruthenium(II) benzoates andp-fluorobenzoates

Complexes of Fe(II) and Ru(II) of the general formula Cp(OC)₂MOC(O)C₆H₄X-p, where M=Fe, X=H, F (1, 2) or M=Ru, X=H, F (3, 4) have been prepared by reactingp-XC₆H₄COOAg with [CpFe(CO)₂]₂ or CpRu(CO)₂I. The crystal structures of complexes1–3 have been determined using X-ray diffraction. Compounds1 and3 are isomorphous. The COO group in1–3 is coordinated as a monodentate ligand. As the latter and the CO ligands are electronically non-equivalent, the coordination of the Cp ligand to the metal is slightly asymmetric.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 395–399, February, 1993.     

A chemo-enzymatic approach to optically active 3-(4-methoxycarbonyl)phenyl-2-methyl-1-propanols

With a view to obtaining both enantiomers of 3-(4-methoxycarbonyl)phenyl-2-methyl-1-propanols, (R)-1 and (S)-1, from the respective racemate, (±)-1, the hydrolysis of its acetate, (±)-2, in the presence of porcine pancreatic lipase (PPL) has been studied. The optical puriry of (R)-1 and (S)-1 thus obtained was unsatisfactory (ee 22–27%), and could not be increased beyondee 33% by repeated enzymatic hydrolysis of the unconverted fraction of the acetate. In contrast with this, the biohydrogenation of 3-(4-methoxycarbonyl)phenyl-2-methyl-2-propen-1-ol (4) with fermentingSaccharomyces cerevisiae afforded (S)-1 of considerably higher optical purity (ee 41–90 %, depending on the strain). The stereochemical correlation of the products obtained in the two biochemical processes under study shows that the PPL-catalyzed hydrolysis of (±)-2 produces preferably (R)-1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 761–766, April, 1995.The authors express their gratitude to the Russian Foundation for Basic Research for financial support (Grant No. 93-03-5893).     

Ozonolysis of olefins VIII. Synthesis of phenoxyacetaldehydes by ozonolysis of allylphenylethers

Summary A new route for the preparation of a series of phenoxyacetaldehydes (2a–j) which are useful intermediates or products, is described. It starts from the easily available allylphenylethers1a–j which are ozonized at –40 °C and further treated with dimethylsulfide to give solutions of the corresponding phenoxyacetaldehydes2a–j; these are purified by column chromatography. Reaction of2a–j with 1-methyl-1-phenylhydrazine leads to the corresponding hydrazones3a–c,3e–g,3i, and3j. The aldehydes can also be transformed into the stable dimethylcetals4a,4e,4h, and4i by reaction with trimethyl orthoformate.

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Ozonolyse von Olefinen, 8. Mitt. Synthese von Phenoxyacetaldehyden durch Ozonolyse von Allylphenylethern

Zusammenfassung Ein neuer Weg, die als Synthone nützlichen Phenoxyacetaldehyde2a–j darzustellen, wird beschrieben. Dazu werden die leicht zugänglichen Allylphenylether1a–j bei –40 °C ozonisiert und anschließend mit Dimethylsulfid reduziert, um Lösungen von2a–j zu erhalten. Reaktion von2a–j mit 1-Methyl-1-phenylhydrazin führt zu den entsprechenden N-Methyl-N-phenylhydrazonen3a–c,3e–g,ei und3j. Die Aldehyde können auch durch Reaktion mit Trimethylorthoformiat in die stabileren Dimethylacetale4a,4e,4h und4i übergeführt werden.

     

Darstellung,chiroptische eigenschaften und absolute Konfiguration von 4,14-disubstituierten [2.2]Metacyclophanen

Resolution of [2.2]metacyclophane-4,14-dicarboxylic acid (2) was achieved by crystallization of its (+)- and (–)--phenylethylamine salts. Chemical correlation with (–)-(S)_p-[2.2]metacyclophane-4-caboxylic acid (–)-11 via its monobromo derivative (–)-8 established the absolute configuration of the dicarboxylic acid as (–)-(S)_p-2. The key compound (–)-8 was prepared by partial lithiation and subsequent carboxylation of 4,14-dibromo[2.2]metacyclophane (1) and resolution with (–)-phenylethylamine.Recently proposed rules correlating the absolute configurations of planarchiral compounds with theirCD-spectra are discussed and a comparison of the chiroptical properties of 4,14-di- and 4-mono-substituted [2.2]metacyclophanes is presented.

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6. Mitt.:C. Glotzmann, E. Langer, H. Lehner undK. Schlögl, Mh. Chem.106, 763 (1975).     

Einwirkung von Schwefel und Ethylenimin auf höhermolekulare symmetrische Ketone, 4. Mitt

The higher molecular ketones, undecanone-6 (1), tridecanone-7 (2), pentadecanone-8 (3), heptadecanone-9 (4) react with ethylenimine and sulfur to give 2,3-disubstituted 5,6-dihydro-1,4-thiazines (9–12) and 2,2-dialkylated thiazolidines (17–20). The reduction of9–12 with formic acid yields the corresponding thiomorpholines13–16 (70–90% yield).9–12 is also obtained by the reaction of -chloro ketones (5–8) and the sodium salt of cysteamine 30–75% yield); cysteamine reacts with1–4 to give the thiazolidines17–20 (37–53% yield).

Teil der DissertationJ. Stalschus, Techn. Hochschule Aachen, 1974.     

The Alkylidenphthalan–1-Alkylisobenzofuran Equilibrium: A Computational Study

Semiempirical (AM1, PM3) and density functional theoretical studies (B3LYP/6-31G*) are reported for the tautomerism of 2-methylidene-2,5-dihydrofurans (3a–e) and the corresponding 2-methylfurans (4a–e) and of benzannulated derivatives (5a–e, 6a–e, 7–14).     

Synthesis,Crystal and Molecular Structures of [Co(MH)2(Thio)2][BF4] · H2O and [Co(DH)2(NH3)2][BF4]

Crystal structures of [Co(MH)₂(Thio)₂][BF₄] · H₂O (I) and [Co(DH)₂(NH₃)₂][BF₄] (II), where MH^– is H₃C–C(NOH)–C(NO^–)–H and DH^– is H₃C–C(NOH)–C(NO^–)–CH₃, were determined by X-ray diffraction. The crystals are monoclinic, space group C2/c, unit cell parameters (for I and II, respectively): a = 22.018(2) Å, b = 7.943(1) Å, c = 11.681(1) Å, = 92.68(1)° and a = 21.436(2) Å, b = 6.400(2) Å, c = 12.389(2) Å, = 113.13(1)°. In both cases, the Co(III) coordination polyhedron is a centrosymmetrical trans-octahedron, N₄S₂ for I and N₆ for II. In the crystals of I and II, the complex cations and the outer-sphere [BF₄]^– anions (and the crystal water molecules in I) form elaborate hydrogen bonding system.     

Synthesis and structures of silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)2Mo(CH2EMe3)2 (E = Si, Ge, Sn)

New silicon-, germanium-, and tin-containing imido-alkyl molybdenum complexes (ArN)₂Mo(CH₂EMe₃)₂ (Ar is 2,6-diisopropylphenyl; E = Si (1), Ge (2), Sn (3)) were prepared in the crystalline state in 58–66% yields by the reactions of the (ArN)₂MoCl₂(DME) complex with alkyllithium derivatives Me₃ECH₂Li (E = Si or Ge) or the Grignard reagents Me₃ECH₂MgCl (E = Ge or Sn). The structures of complexes 1–3 and the known analog (ArN)₂Mo(CH₂Bu^t)₂ (4) were established by X-ray diffraction analysis. Complexes 1–3 were found to be isostructural. The coordination environment about the Mo atom can be described as a distorted tetrahedron. Complex 4 has a similar structure. The Mo-C distance tends to decrease with increasing electron donating ability of the EMe₃ group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 597–600, March, 2005.     

Über die Reaktionen von Guanidin bzw. Harnstoff mit Aminonitrilen

The aminonitriles3a–f react with guanidine inDMF to yield the 5,5-resp. 5-subtituted imidazolidine-2,4-diimines2a–d resp.2f, whereas2e could not be isolated. 7,14-diazadispiro[5.1.5.2]-pentadecan-15-on (7)¹, 4-imino-1,3-diazaspiro[4.5]decan-2-one (8a)¹ and the 2,4-diaminotriazine (9)¹ were isolated as byproducts.1-Aminocyclohexancarbonitrile (3a) reacts with urea to the 4-imino-1,3-diazaspiro[4.5]decan-2-one (8a)¹;8a can be prepared from (1-cyancyclohexyl)urea (11a) as well. The structures of the new compounds are proved by NMR-, IR- and mass spectra and the mechanism of the reaction is discussed.

Herrn Prof. Dr.G. Zigeuner zum 60. Geburtstag gewidmet.     

Synthesis of Double-Armed Benzo-15-crown-5 and Their Complexation Thermodynamics with Alkali Cations

A series of double-armed benzo-15-crown-5 lariats (3–8) have been synthesized by the reaction of 4′, 5′-bis(bromomethyl)-benzo-15-crown-5 (2) with 4-hydroxybenzaldehyde, phenol, 4-chlorophenol, 4-methoxyphenol, 2-hydroxybenzaldehyde, and 4-acetamidophenol in 43 ~ 82% yields, respectively. The complex stability constants (K _S) and thermodynamic parameters for the stoichiometric 1:1 and/or 1:2 complexes of benzo-15-crown-5 1 and double-armed crown ethers 3–8 with alkali cations (Na⁺, K⁺, Rb⁺) have been determined in methanol–water (V/V=8:2) at 25 °C by means of microcalorimetric titrations. As compared with the parent benzo-15-crown-5 1, double-armed crown ethers 3–8 show unremarkable changes in the complex stability constants upon complexation with Na⁺, but present significantly enhanced binding ability toward cations larger than the crown cavity by the secondly sandwich complexation. Thermodynamically, the sandwich complexations of crown ethers 3-8 with cations are mostly enthalpy-driven processes accompanied with a moderate entropy loss. The binding ability and selectivity of cations by the double-armed crown ethers are discussed from the viewpoints of the electron density, additional binding site, softness, spatial arrangement, and especially the cooperative binding of two crown ether molecules toward one metal ion.     

Synthesis and Structures of New Enaminones

Two isomeric enaminones were obtained by reaction of ethyl 2-hydroxy-4-(4-hydroxy-6-methyl2H-pyran-2-on-3-yl)-4-oxo-2-butenoate (1) and amines (aniline, benzylamine, butylamine and tyramine) in ethanol. The structures of isomers were studied by ¹³C and ¹H NMR spectra, whereas in the case of isomers 2b, 3a, and 4a (Scheme 1), the crystal structures have been determined by single crystal X-ray diffractometry. The compounds 2b and 3a exist in the solid state as N–C=C–C=O, whereas 4a is in the N–C=C–C–OH tautomeric form (Scheme 2, form A and B, respectively). All three structures exhibit very short intramolecular hydrogen bonds of O–H···O [in the range 2.396(3) – 2.448(3) Å] and N–H···O [in the range 2.580(5) – 2.679(3) Å] type, that are reinforced by delocalization. The crystal structures are in addition stabilized by C–H···O weak hydrogen bonds. In 2b and 3a, the discrete dimers are formed by eight-membered ring containing hydrogen bonds; in 4a, the infinite chains along [1 0 1] direction are formed.     

Substituted benzimidazo[2,1 -h]pteridine-2,4-diones

5-Alkyl-5,6-dihydrobenzimidazo[2,1 -h]pteridine-2,4(1H,3H)-diones (4 a–d) have been synthesised by the condensation of 2-(alkyl-aminomethyl)benzimidazole dihydrochloride (1 a–d) with 5-bromobarbituric acid (2). Similarly, 5-alkyl-5,6-dihydro-4 a-nitrobenzimidazo[2,1 -h] pteridine-2,4(3H,4aH)-diones (10 a–d) have also been synthesised by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (8) followed by cyclisation of the intermediate 5-[(benzimidazol-2-ylmethyl)alkylamino]-5-nitrobarbituric acid (9 a–d) with 5% NaOH. Thermal cyclisation of the intermediates9 a–d have also been studied. Methylation of the compound10 a has been carried out with CH₃I and K₂CO₃ usingD M F as solvent to confirm cyclisation. The structures are supported by elemental analyses, IR and PMR spectra.

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Substituierte Benzimidazo[2,1 -h]pteridin-2,4-dione

Zusammenfassung Die 5-Alkyl-5,6-dihydrobenzimidazo[2,1 -h]pteridin-2,4(1H,3H)-dione4 a-d wurden mittels Kondensation von 2-(Alkylaminomethyl)benzimidazolidhydrochloriden1 a–d mit 5-Brombarbitursäure (2) dargestellt. In ähnlicher Weise wurden die 5-Alkyl-5,6-dihydro-4a-nitrobenzimidazo[2,1 -h]pteridin-2,4(3H,4aH)-dione10 a–d über die Kondensation von1 a–d mit 5-Brom-5-nitrobarbitursäure (8) und nachfolgender Cyclisierung der intermediären 5-[(Benzimidazol-2-ylmethyl)alkylamino]-5-nitrobarbitursäuren9 a–d mit 5% NaOH dargestellt. Die thermische Cyclisierung der Produkte9 a–d wurde ebenfalls untersucht. Die Verbindungen wurden mittels Elementaranalyse, IR und PMR charakterisiert.

     

Prototropic acetylene-allene isomerization in planarly chiral ferrocenes. Intramolecular acymmetric induction in the course of the formation of chiral axis

Racemic 2-trimethylsilyl- and 2-trimethylstannyl-1-(3-phenyl-2-propynyl)ferrocene (rac-1a,b) as well as the dextrorotatory specimen of the latter, (+)-1b, were synthesized in two steps from racemic 1-formyl-2-trimethylsilyl- and 1-formyl-2-trimethylstannylferrocenes (2a,b) or from the levorotatory specimen of the latter, (–)-2b, respectively. On the contact with strongly alkaline alumina compounds1a,b and (+)-1b undergo diastereoselective prototropic acetylene-allene rearrangement to give predominantly one of the two possible stereoisomers of 2-trimethylsilyl- or 2-trimethylstannyl-1-(3-phenyl-1,2-propadienyl)ferrocenes,rac-4a,b or (+)-4b, depending on the starting material (d. e. 30–40 %). The extent of intramolecular asymmetric induction in the formation of the axially chiral fragment during the transformation of (+)-1b to (+)-4b is estimated at 38 %.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1111– 1115, June, 1994.The work was carried out with financial support from the Russian Fundamental for Basic Research (Project No.93-03-5827).     

Synthese arylsubstituierter 2-Pyrimidinamine,Dihydro-2-pyrimidinamine und Pyrimido[1,2-a]pyrimidine durch Reaktion von Guanidin mit Chalkonen

4- and 4-methoxy-, 4-hydroxy- and 2-hydroxychalcone4 e,k,f andg, respectively, are transformed by action of guanidine in benzene to yield 4-(4-methoxyphenyl)-6-phenyl-2-pyrimidinamine (6 e=6 k) and hydroxyphenylpyrimidinamines6 f andg, respectively. In contrast, 4- and 4-chlor-, 4-brom- and 4-phenylchalcone4 h,l–n resp. react with guanidine under analogous conditions to give 4,6-diaryl-1,4-dihydro-2-pyrimidinamines5 h,l–n. The bases5 h,l–n also tend to aromatize, but they can be stabilized by transformation into salts5 h,l–n · HCl with hydrochloric acid. Heating of5 n inDMF under atmospheric oxygen yields 4-(4-biphenyl)-6-phenyl-2-pyrimidinamine (6 n). Action of guanidine on 4-nitrochalcone4 o in chloroform affords 2-amino-4-nitrophenyl-6-phenyl-tetrahydro-4-pyrimidinol8 o, which is transformed by hydrochloric acid into 6-nitrophenyl-dihydropyrimidinamine-hydrochloride5 o · HCl. Treating of the latter with sodiummethylat in methanol yields the very stable dihydropyrimidinamine5 o. Action of guanidine on 4-chlor- and 4-bromchalcone4 h andm respectively (in addition to5 h andm) yields 2,4,6,8-tetraaryl-1,4-dihydro-2H-pyrimido[1,2-a]pyrimidines7 h andm, respectively.

Herrn Prof. Dr.Erwin Schauenstein mit den besten Wünschen zum 65. Geburtstag gewidmet.     

IR spectroscopic study of thioacrolein and its photoisomerization to methylthioketene

The molecules of thioacrolein (1) and metylthioketene (3), which are labile under normal conditions, have been studied by the matrix Fourier transform infrared spectroscopy method. Compound1 was obtained by vacuum pyrolysis (1120 K, 10^–4 Torr) of diallyl sulfide. The analysis of its IR spectrum shows that1 exists as a mixture ofs-trans ands-cis conformers. UV irradiation ( > 248 nm) of matrix isolated1 results in a 1,3 hydrogen shift and the formation of3, which is characterized by a strong band of antisymmetric stretching vibrations of the thioketene fragmentvC=C=S at 1777.2 cm^–1. The experimental IR bands of molecules1 and3 were assigned to fundamental modes. The relatively low frequencies of the stretching vibrations of the double bonds (vC=C at 1598.0 cm^–1 andvC=S at 1071.8 cm^–1) and the heightened frequency of the C-C single bond stretching (vC-C 1173.7 cm^–1) in the spectrum of1 indicate appreciable delocalization of the electron density in the conjugated -orbital system.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 464–470, March, 1995.     

IR study of the peculiarities of the stabilization of the NH4Na-Y zeolite structure during its hydrothermal dealumination

The variations in the structure of deep-level calcinated NH₄Na-Y zeolite (68 % NH₄ ⁺, Si/Al = 2.56) at 873 K (stage I of the hydrothermal dealumination) as a result of ammonation and subsequent calcination in water vapor at 973 and 1023 K (stageII) were studied using the IR spectra of zeolite framework vibrations. It was shown that ammonation of the product of stageI promotes the formation of linear disiloxane bonds and extra-framework =Al^VI-OH species identified by absorption at 482, 1196 cm^–1, and 524, 612, 829 cm^–1. The ammonation is also accompanied by an increase in the excessive negative framework charge (ENFC), which is manifested in the high-frequency (HF) shift of the bands that have maxima in thev _as (TO₄) region and equals 10 cm^–1, and also by a decrease in the unit cell parameter (a ₀) by 0.14 Å. The decrease in both the ENFC anda ₀ for the products of stageII, v _as (TO₄) = 10–20 cm^–1 and a ₀ = 0.07–0.14 Å, is due to the formation of nonlinear disiloxane bonds and non-framework aluminum hydroxide species identified by the absorption bands at 478, 1173 cm^–1 and 530, 615, 835 cm^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 660–664, April, 1993.     

Reaction of (C6F5)2HGeGeH(C6F5)2 with triethylbismuth: molecular structure of [(C6F5)2Ge]4Bi2

The reaction of (C₆F₅)₂HGeGeH(C₆F₅)₂ with triethylbismuth affords a new polynuclear germylbismuth derivative, [(C₆F₅Ge]₄Bi₂ (1). The metal framework of molecule1 has the form of a gable roof built by two central Bi atoms and four peripheral Ge atoms with covalent Bi-Bi bonds [3.045(3) Å], Bi-Ge [2.724(5)-2.755(4) Å] and Ge-Ge [2.444(6), 2.465(6) Å].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 921–924, May, 1994.     

Gemeinsame Einwirkung von elementarem Schwefel und Äthylenimin auf Ketone, 2. Mitt.

Zusammenfassung Bei der gemeinsamen Einwirkung von Schwefel und Äthylenimin auf 4-Heptanon, Cyclopentanon, Cyclohexanon und Cyclooctanon bilden sich in glatter Reaktion 5,6-Dihydro-4H-1,4-thiazine (3–6). Als Nebenprodukte von3, 4 und5 fallen die dem jeweiligen Keton zugrunde liegenden 2,2-dialkylierten Thiazolidine (7–9) an. Bei Einsatz von Phenylisopropylketon in diese Reaktion wird dagegen das 2-Isopropyl-2-phenylthiazolidin (12) zum Hauptprodukt, während das entsprechende 5,6-Dihydro-2H-1,4-thiazin (11) nur in untergeordnetem Maße entsteht.Die Reaktionsmechanismen sowohl der 5,6-Dihydro-1,4-thiazin-als auch der Thiazolidin-Bildung werden diskutiert.Die Umsetzung der 5,6-Dihydro-1,4-thiazine (1, 3–5, 11) mit überschüss. Ameisensäure führt zu N-Formylthiomorpholinen (13–17), die sich mit verd. HCl glatt zu den entsprechenden Thiomorpholinen (18–22) verseifen lassen.

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Concomitant action of elementary sulfur and gaseous ammonia upon ketones, LXXI. Concomitant action of elementary sulfur and ethylenimine upon ketones, II

The interaction of sulfur and ethylenimine with 4-heptanone, cyclopentanone, cyclohexanone, and cyclooctanone leads to 5.6-dihydro-4H-1.4-thiazines (3–6) in good yields. As byproducts of3, 4 and5 2.2-dialkylated thiazolidines (7–9, resp.) are isolated. When this reaction is carried out with phenyl isopropyl ketone, however, the main product is 2-isopropyl-2-phenylthiazolidine (12), the corresponding 5.6-dihydro-2H-1.4-thiazine (11) is but formed in a small quantity.The mechanisms of the formation of 5.6-dihydro-1.4-thiazines, as well as the formation of the thiazolidines are discussed.Reaction of 5.6-dihydro-1.4-thiazines (1, 3–5, 11) with excess formic acid leads to N-formylthiomorpholines (13–17) which can be easily saponified with dil. HCl to the corresponding thiomorpholines (18–22).

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Herrn Prof. Dr.O. Hromatka mit herzlichen Grüßen zum 65. Geburtstag gewidmet

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70. Mitt.:F. Asinger, H. Offermanns, D. Neuray undF. Abo Dagga, Mh. Chem.101, 500 (1970)

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Teil der DissertationK. H. Lim, Techn. Hochschule Aachen, 1969.

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Teil der DissertationD. Neuray, Techn. Hochschule Aachen, 1969

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1. Mitt.:F. Asinger, H. Offermanns, W. Pürschel, K. H. Lim undD. Neuray, Mh. Chem.99, 2090 (1968).     

The synthesis of 4-(2,6,10-trimethyl-1,3,5,9-undecatetraenyl)benzoic acid based on alkoxy alkene-acetal condensation

4-(2,6,10-Trimethyl-1,3,5,9-undecatetraenyl)benzoic acid (1) was synthesized starting from ethyl 4-formylbenzoate (2) and linalool. The key intermediate, ethyl 4-(2-methyl-3-oxo-1-propenyl)benzoate (5), was obtained by the addition of diethyl acetal (3), prepared from2, to ethyl 1-propenyl ether (EPE) followed by the hydrolysis of the resulting adduct.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 914–915, May, 1993.     

Thermal decomposition of strained spiro(1-pyrazoline-3,1′-cyclopropanes)

Pyrolysis (320–370 °C) of polycyclic 1-pyrazolines1 and2, obtained by 1,3-dipolar cycloaddition of diazocyclopropane to 3,3-dimethylcyclopropene and spiro[2,3]hex-1-ene, yields complex mixtures of isomeric hydrocarbons, substituted methylenecyclopropanes being the main components. Pyrolysis of 6-ethenyl- (4) and 6-methoxy-6-methylcarbonyl-4,5-diazaspiro[2,4]hept-4-enes (6) at 310–320 °C proceeds more unambiguously to give vinyl- (18) and 1-methoxy-1-methylcarbonylspiropentanes (20) in 85 and 95 % yields with respect to the transformed pyrazolines. Dediazotization of pyrazoline3 obtained from diazocyclopropane and benzvalene requires more drastic conditions (–440 °C) and produces indane.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2203–2207, November, 1995.This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-08902).