Imino-bridged heterocycles. III . Synthesis of mono-bridgehead substituted 11H-benzo[5,6]cyclohepta[1,2-c]pyridin-6,11-imines by regiospecific amine to olefin cyclizations

Employing regiospecific amine to endocyclic olefin and hydroxylamine to exocyclic olefin cyclizations, we have developed pathways to two isomeric, bridgehead methyl-substituted benzo[5,6]cyclohepta[1,2-c]pyridin-6,11-imines. Acid catalyzed cyclization of 5 to 6 was accomplished under exceedingly mild conditions (silica gel/chloroform), whereas, thermal cyclization of 20 to generate 21 was performed analogously to the dibenzo[a,d]cyclohepten-5,10-imine system.     

Synthesis of benzo[b]phenanthro[d]thiophenes

The synthesis of benzo[b]phenanthro[1,2-d]thiphene ( 1 ), benzo[b]phenanthro[4,3-d]thiophene ( 2 ), benzo-[b]phenanthro[2,1-d]thiophene ( 3 ) and benzo[b]phenanthro[3,4-d]thiophene ( 4 ) from appropriately substituted olefines by photochemical cyclodehydrogenation is described. The photolysis of olefin 9 gave a mixture of 4 and anthra[1,2-b]benzo[d]thiophene ( 5 ).     

Derivate des 5, 9-Methano-6, 7,8, 9-tetrahydro-5 H-benzocycloheptens und Umlagerungen zum 1, 4-Äthano-1,2,3,4-tetrahydronaphtalin-System

Derivatives of 5,9-Methano,7,8,9-tetrahydro-5H-benzocycloheptene and Rearrangements to the 1,4-Ethano-I,2,3,4-tetrahydronaphthalene System Reduction of the oxime 2 with Raney alloy gives the amine 3a , with AlH₃ a mixture of the isomeric amines 3a and 3b , whilst LiAlH₄ yields the aziridines 4a and 4b . The bicyclo[3.2.1]octane 4b rearranges under acidic conditions to the bicyclo[2.2.2]octane 5 . The olefin 7 can be converted to the aminoalcohol 9 via the epoxide 8 and to the amine 13 using iodine isocyanate: the carbon skeleto. remains intact. However, treatment of the olefin 17 with iodine isocyanate leads to the bicyclo[2.2.2]octanes 21 and 24 in which a skeletal rearrangement has taken place. The configuration was determined by NMR. and X-ray analysis.     

Face Selectivity of the Diels-Alder Additions of Exocyclic Dienes Grafted onto 7-Oxabicyclo[2.2.1]heptanes

Stereoselective syntheses of 2exo, 3exo-bis (chloromethyl)-5-[(Z)-chloromethylidene]- ( 9 ), 2exo, 3exo-bis (chloromethyl)5-[(E)-chloromethylidene]- ( 10 ) and 2exo, 3exo-bis(chloromethyl)-5-[(E)-methoxymethylidene]-6-niethylidene-7-oxa-bicyclo[2.2.1]heptane ( 13 ) are presented. Double elimination of HCI from 9, 10 and 13 yielded 2-[(Z)-chloromethylidene]- ( 14 ), 2-[(E)chloromethylidene]- ( 15 ) and 2-[(E)-methoxymethylidene]-3,5,6-mmethylidene-7-oxabicycio[2.2.1]heptane ( 18 ), respectively, without loss of the olefin configuration. Ethylene tetracarbonitrile (TCE) and N-phenyltriazolinedione (NPTAD) added to these new exocyclic dienes and tetraenes preferentially onto their exo-face. The same face selectivity was observed for the cycloadditions of TCE to the (Z)- and (E)-chlorodienes 9 and 10 , thus realizing a case where the kinetic stereoselectivity of the additions is proven not to be governed by the stability of the adducts. The exo-face selectivity of the Diels-Alder additions of dienes grafted onto 7-oxabicyclo [2,2.1]heptanes contrasts with the endo-face selectivity reported for a large number of cycloadditions of dienes grafted onto bicyclo[2.2.1]heptane skeletons.     

Unexpected Formation of a [4]Radialene and Dendralenes by Addition of Tetracyanoethylene to a Tetraaryl[5]cumulene

The use of cumulenes in synthetic transformations offers the possibility to form structurally interesting and potentially useful conjugated molecules. The cycloaddition reaction of a tetraaryl[5]cumulene with the electron‐deficient olefin tetracyanoethylene affords unusual products, including functionalized dendralenes and alkylidene cyclobutanes, as well as a symmetric [4]radialene that shows unique solvatochromism, with λ_max values approaching the near‐IR region. These carbon‐rich products have been investigated spectroscopically and by X‐ray crystallographic analysis (five structures). The cycloaddition reaction sequence has also been explored by mechanistic and theoretical studies. The obtained results clearly demonstrate the potential of [5]cumulenes to serve as precursors for unprecedented conjugated structures.     

Die Chlorierung des Hexamethyl-Dewar-Benzols

It has been shown that addition of chlorine to hexamethyl-Dewar-benzene is a stereospecific process and yields exclusively 5-endo-chloro-hexamethyl-bicyclo[2.1.1]hexenyl chloride. This supports the suitability of SbCl₅ as a model reagent for olefin chlorination.     

Enantioselectivity and cis/trans-Selectivity in Dirhodium(II)-Catalyzed addition of diazoacetates to olefins

The Rh¹¹-catalyzed carbenoid addition of diazoacetates to olefins was investigated with [Rh₂{(4S)-phox}₄] ( 1 ;phox = tetrakis[(4S)-tetrahydro-4-phenyloxazol-2-one]), [Rh₂{(2S)-mepy}₄] ( 2 ; mepy = tetrakis[methyl (2S)-tetrahydro-5-oxopyrrole-2-carboxylate]), and [Rh₂(OAc)₄] ( 3 ). While catalysis with 2 and 3 afford preferentially trans-cyclopropanecarboxylates, the cis-isomers are the major products with 1 . In general, the enantioselectivities achieved with 1 and 2 are comparable. Additions catalyzed by 1 are strongly sensitive to steric effects. Highly substituted olefins afford cyclopropanes in only poor yield. The preferential cis-selectivity observed in reactions catalyzed by 1 is attributed to dominant interactions between the ligand of the catalyst and the substituents of both olefin and diazoacetate, which overrule the steric interactions between olefin and diazoacetate in the transition state for carbene transfer.     

Synthesis,structural characterization and catalytic potential of oxidovanadium(IV) and dioxidovanadium(V) complexes with thiazole-derived NNN-donor ligand

Reaction between the tridentate NNN donor ligand, (E)-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)benzo[d]thiazole (HL), and V₂O₅ in ethanol gave a new vanadium(V) complex, [VO₂L] (1), while the similar reaction by using [V^IVO(acac)₂] as the metal source gave two different types of crystals related to compounds [VO₂L] (1) and [V^IVO(acac)L] (2). The molecular structures of the complexes were determined by single-crystal X-ray diffraction and spectroscopic characterization was carried out by means of FT-IR, UV–vis and NMR experiments as well as elemental analysis. The oxidovanadium(IV) and dioxidovanadium(V) species were used as catalyst precursors for olefin oxidation in the presence of hydrogen peroxide (H₂O₂) as an oxidant. Under similar experimental conditions, the presence of 1 resulted in higher oxidation conversion than 2.     

A new regioselective synthesis of 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-ones,and [1]benzopyran-6-ones

Through an anti-Markovnikow hydration of some olefin derivatives of 4-hydroxy-2-pyrones, and 4-hydroxy-coumarins, followed by a regioselective intramolecular dehydration, involving the primary alcohols obtained and the enolic oxygen of the rings, promoted by Amberlyst 15 in boiling toluene, the new heterocycles 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-one ( 3 ) and [1]benzopyran-6-ones ba,c were obtained in fair yields.     

2-Vinylcyclobutanones by Cycloaddition of Vinylketenes to Simple Olefins

Selected [2+2]-cycloadditions of three alkylvinylketenes 2 to one mono- and seven dialkyl-olefins 3 yielded eleven 2-alkyl-2-vinylcyclobutanones 4 (Tables 1 and 2). Three methods were compared, all involving in situ generation of the ketenes 2 by HCl-elimination from α,β-unsaturated acid chlorides 1 ; the most effective employed a large excess of olefin 3 and a high reaction temperature. The [2+2]-cycloadditions were fully regio- and stereoselective with respect to the olefin 3 , but less so with respect to the ketene 2 , so that - where possible - two stereoisomers of 4 resulted, namely A and B , whose configurations were determined from their ¹H-NMR, spectra, mechanistic considerations and, in one case, 4f , by chemical correlation with a previously known cycloadduct 8 .     

乙烯聚合水杨醛亚胺锆配合物的合成、结构和固定化

合成和表征了2个锆的配合物：Bis[N-(3-tert-butylsalicylidene) allylaminato] zirconium dichloride (4)和Bis[N-(3-tert-butylsali-cylidene)-iso-butylaminato] zirconium dichloride (5)，并且得到了配合物4的单晶结构。在引发剂的作用下，配合物4和苯乙烯进行自由基共聚，得到高分子化催化剂6。在助催化剂MMAO的存在下，4，5和6都可以催化乙烯聚合。最高活性为3.7×10⁶ g PE·(mol Zr)^-1·h^-1。     

Phase transfer Pd(0) catalyzed polymerization reactions. III. Polymerization by cross-coupling of alkyl–boron compounds and aromatic halides catalyzed by PdCl2 (dppf) and bases

This paper describes a novel polymerization reaction which consists of a sequence of hydroboration of a diolefin with 9-borabicyclo[3.3.1]nonane (9-BBN) followed by the intermolecular cross-coupling of the resulting 1,1′-bis(B-alkanediyl-9-borabicyclo[3.3.1]nonanes with dihaloarenes. The reaction is performed in the presence of dichloro[1,1′-bis(diphenylphosphino)ferrocene] palladium (II) [PdCl₂ (dppf)], a base, and a phase transfer catalyst. Both steps are performed in the same reaction flask. Alternatively, this polymerization reaction can be applied to bifunctional monomers containing an olefin and a haloarene group, for example, p-bromostyrene.     

Tricyclo [3.3.2.03,7]decan (9-Homo-nor-adamantan) Synthese und Umwandlungen

Tricyclo[3.3.2.0^3,7]decane (9-Homo-nor-adamantane). Synthesis and Transformations A synthesis of tricyclo [3.3.2.0^3,7]decane (=9-homo-nor-adamantane; 1 ), which belongs to the adamantaneland, a family of nineteen isomeric C₁₀H₁₆ hydrocarbons, is described, as well as derivatives thereof. Treatment of protoadamantan-5endo-ol (11) with either thionyl chloride or phosphorus pentachloride yielded under rearrangement the chloride 18 , and solvolysis of the 5endo-chloro-protoadamantane (16) led to the acetate 26, 18 and 26 having both the tricyclo [3.3.2.0^3,7]decane skeleton. Subsequent transformations gave the title compound 1 as well as the corresponding olefin 8 .     

1-Methoxycarbonyl-substituiertes 2,3-Dihydropyridin-4(1H)-on (= Methyl-1,2,3,4-tetrahydro-4-oxopyridin-1-carboxylat) als Chromophor für die photochemische [2 + 2]-Cycloaddition

1-Methoxycarbonyl-Substituted 2,3-Dihydropyridin-4(1H)-one(= Methyl 1,2,3,4-Tetrahydro-4-oxopyridine-1-carboxylate) as Chromophore for Photochemical [2 + 2]-Cycloadditions With olefins having an electron-acceptor as well as with olefins having an electron-donor substituent, 1-methoxycarbonyl-substituted dihydropyridinone 12 undergoes [2 + 2] cycloaddition in good preparative yields. The photochemical cycloaddition is highly regioselective. For preparative purposes, the ring junction can be equilibrated to the thermodynamically more stable cis-junction. Only the ‘endo’/‘exo’ selectivity at the C-atom bearing the olefin substituent cannot be controlled. The photodimerization of 12 is the only side reaction. Using a slight excess of the olefin, the photodimerization can be suppressed. The protecting group at the N-atom of the dihydropyridinone can be varied in order to introduce an internal sensitizer, as shown with 1-acyl-substituted compound 29 , which underwent the cycloaddition process even with sunlight.     

Preparation of novel bicyclic piperazines by reduction of bicyclo[4.2.2]diketopiperazines: rearrangement involving 1,2-bond migration

Reduction of (1R,6R)-7,9-diazabicyclo[4.2.2]dec-3-ene-8,10-dione (5) with lithium aluminum hydride gave a mixture of the expected (1R,6R)-7,9-diazabicyclo[4.2.2]dec-3-ene (2) as well as 7,9-diazabicyclo[4.3.1]dec-3-ene (3), resulting from 1,2-σ (C-C) migration of the pendant cis-2-butenyl ring. More of the rearranged product was observed in polar solvents and upon the addition of HMPA. The relief of ring strain imparted by the olefin may promote this rearrangement, as it was not observed when the olefin was reduced prior to the reduction.     

Polystyrene anchored rhodium (I) bidentate ligand complexes as catalysts for hydrogenation

Polystyrene supported Rh(I) AA′ (AA′ = anthranilic acid, 2,2′-bipyridine or 1,10-phenanthroline) complexes catalyse the hydrogenation of monoolefins (terminal, cyclic and internal) and dienes. Ethyl sorbate undergoes saturation via the monoene intermediate. Thiscis olefin reacts faster than thetrans isomer. The rate law for the reaction is: Rate α [catalyst] [substrate] [H₂].     

Untersuchungen über Allylgruppenwanderungen in aliphatischen Carbenium-Ionen

Investigations on the Migratory Aptitude of Allyl Groups in Aliphatic Carbenium-Ions The acetolysis (80°) of the 4-bromobenzenesulfonates given in Scheme 6 were investigated in regard to determine type allyl/methyl migratory aptitudes in the secondary carbenium ion a (Scheme 24). In all cases olefins (about 80%) and acetates (about 20%) were formed which can be derived from the rearranged tertiary carbenium ions b (being formed by allyl group migration) and c (being formed by methyl group migration). Olefin A and acetate H , originated in carbenium ion a, occurred in the acetolysis mixture only in minor amounts (<2%). By acetolysis of [l4C]-20, isolation of [¹⁴C]-4,5-dimethyl-l, 3-hexadiene ([¹⁴C]-45), and degradation of this diene (Scheme 16) it could be shown (4 Scheme 15) that the ions b and c (Scheme 24, R¹? R⁴?H) are not interconverted by a [1,2]-hydride shift (extent < 1%). Since olefin D arises by proton loss from ion b as well as from ion c , [¹⁴C]-4,5-dimethyl-l,4-hexadiene ([¹⁴C]? 44? D, R¹? R⁴? H) was also degraded (cf. Scheme 15 and Scheme 17). It was found that [¹⁴C]- 44 contained 48% of the label in the methyl group at C( 4 ) and 52% in the methyl groups at C( 5 ), i.e. 48% of 44 is formed via the allyl migration path and 52% via the methyl migration path. In addition, acetolysis of d3-20 and product analysis showed, that the d3-ally1 moiety migrates as expected only in a [1,2]-fashion. Product analysis of the acetolysis mixtures of erythro- and threo- 24 (cf. Scheme 19 and Tables 4 and 5) revealed that carbenium ion a must exist as an intimate ion pair (with the 4-bromobenzenesulfonyloxy-ion) which has lost its configuration at C( 1 ) only partially. This is indicated by reversed ratios (1: 11 and 10: 1, resp.) in the formation of erythro- and threo-2,3,4-trimethyl-l, 5-hexadiene (erythro- and threo- 77 ) arising from ion b (Scheme 24, R¹? R³ ? H, R⁴? CH,). The acetolysis of 1,2,2,4-tetramethyl-4-pentenyl4-bromobenzenesulfonate ( 23 ) was not studied in detail, but the appearance of a seventh product in the olefin part cannot be explained by the genesis paths in Scheme 24. Thus, it may be concluded that in this case a third tertiary carbenium ion d ₃ (Scheme 21) is produced by cyclization of a ₃. Cyclizations of this type are known to occur in carbenium ions bearing β-substituted allyl groups (see Scheme 22). The kinetic data of the acetolysis of all 4-bromobenzenesulfonates (Table 6) are in accord with a rate determining ionization step leading to a since all activation enthalpies resp. entropies are within 25.5 L± 0.6 kcal/mol resp. ?0.2 ± 1.7 e.u. The migratory aptitudes given in Table 7 show, that allyl groups migrate only slightly easier than methyl groups in ion a . This is in strong contrast to allyl substituted methylcyclohexadienyl cations (generated in the acid catalyzed dienone/phenol and dienol/benzene rearrange-ment) which undergo exclusively [1,2]-ally1 migrations (Schemes 3-5).     

Fine‐Tuning the Reactivity and Stability by Systematic Ligand Variations in CpCoI Complexes as Catalysts for [2+2+2] Cycloaddition Reactions

CpCo^I‐olefin‐phosphite and CpCo^I‐bisphosphite complexes were systematically prepared and their reactivity in [2+2+2] cycloaddition reactions compared with highly active [CpCo(H₂C?CHSiMe₃)₂] ( 1 ). Whereas 1 is an excellent precursor for the synthesis of [CpCo(olefin)(phosphite)] complexes ( 2 a – f ), [CpCo(phosphite)₂] complexes ( 3 a – e ) were prepared photochemically from [CpCo(cod)]. The complexes were evaluated in the cyclotrimerization reaction of diynes with nitriles yielding pyridines. For [CpCo(olefin)(phosphite)], as well as some of the [CpCo(phosphite)₂] complexes, reaction temperatures as low as 50 °C were sufficient to perform the cycloaddition reaction. A direct comparison showed that the order of reactivity for the complex ligands was olefin₂>olefin/phosphite>phosphites₂. The complexes with mixed ligands favorably combine reactivity and stability. Calculations on the ligand dissociation from [CpCo(olefin)(phosphite)] proved that the phosphite is dissociating before the olefin. [CpCo(H₂C?CHSiMe₃){P(OPh)₃}] ( 2 a ) was investigated for the co‐cyclization of diynes and nitriles and found to be an efficient catalyst at rather mild temperatures.     

Dynamic 1H NMR spectroscopy of η2-ethylene transition metal complexes

The low-temperature ¹H NMR spectra of bis(ethylene)trimethylphosphinenickel (1), η⁵-cyclopentadienyl(ethylene)methylnickel (2a), bis(ethylene)-η⁵-cyclopentadienylcobalt (2b), [bis(1-ethyl-2,4,6-triphenylphosphorinyl)nickel]P,P′-nickel(ethylene) (3) and η⁵-cyclopentadienyl(ethylene)hydrido(triphenylphosphine)ruthenium (4) exhibit {AA′B′B} (1) {ABB′A} (2a and 2b), {ABA′B′} (3) or {ABCD} (4) spin patterns, respectively, for the complexed ethylene. A full line shape analysis including all the proton couplings was performed for the ethylene rotation in 1, 2a and 2b. In addition to olefin rotation, a reversible intramolecular β-H-elimination was confirmed for 4 by magnetization transfer experiments.     

Use of water in aiding olefin/paraffin (liquid + liquid) extraction via complexation with a silver bis(trifluoromethylsulfonyl)imide salt

This paper describes the extraction of C₅–C₈ linear α-olefins from olefin/paraffin mixtures of the same carbon number via a reversible complexation with a silver salt (silver bis(trifluoromethylsulfonyl)imide, Ag[Tf₂N]) to form room temperature ionic liquids [Ag(olefin)_x][Tf₂N]. From the experimental (liquid + liquid) equilibrium data for the olefin/paraffin mixtures and Ag[Tf₂N], 1-pentene showed the best separation performance while C₇ and C₈ olefins could only be separated from the corresponding mixtures on addition of water which also improves the selectivity at lower carbon numbers like the C₅ and C₆, for example. Using infrared and Raman spectroscopy of the complex and Ag[Tf₂N] saturated by olefin, the mechanism of the extraction was found to be based on both chemical complexation and the physical solubility of the olefin in the ionic liquid ([Ag(olefin)_x][Tf₂N]). These experiments further support the use of such extraction techniques for the separation of olefins from paraffins.