trans-chloro(N,N-dimethyl-d-phenylglycine)-(3-methyl-1-phenylpent-1-ene)platinum(II) complexes. HPLC separation and identification of all the diastereomers

The diastereomeric trans-chloro(N,N-dimethyl-d-phenylglycine)(3-methyl-1-phenylpent-1-ene)platinum(II) complexes, derived by coordination of the enantiomeric and geometric isomers of 3-methyl-1-phenylpent-1-ene (2), were separated by HPLC. Four trans- and two cis-olefin complexes were recognized in the chromatogram. The configuration of all chiral centers of the olefin in the six complexes were assigned. Under the conditions of preparation, the pairs of diastereomers 1R,2R,3S/1S,2S,3S and 1S,2S,3R/1R,2R,3R were formed in a ratio > 1 for the trans-isomer, whereas the cis-isomer gave the 1R,2S,3S and 1S,2R,3R epimers only. The complexes do not epimerize on standing at room temperature in solution; similar behaviour of the corresponding complexes of trans-stilbene (4C) indicates that the conjugated aromatic double bond is coordinated more strongly than those aliphatic and cycloaliphatic olefins.The efficient HPLC separation of the diasteromeric complexes 2C, permits the enantiomeric analysis of 2, as well as the preparative resolution of the olefin.     

Effect of the rigidity and flexibility features of 2-pyridinyl or 8-quinolinyl based N-N chiral ligands on the stereochemical properties of [Pd(N-N)Cl2] complexes

The [Pd(N-N^∗)Cl₂] complexes have been obtained, as yellow solids, in almost quantitative yields; N-N^∗ indicate bidentate chiral ligands (S_a)-1, (S_a)-2, (S,S)-3, (R,R)-4, containing the rigid 2-pyridinyl or 8-quinolinyl building block skeleton and the C₂-symmetric chiral framework trans-2,5-dimethylpyrrolidinyl or (S)-(+)-2,2′-(2-azapropane-1,3-diyl)-1,1′-binaphthalene. The ligands pairs have the same C₂-symmetric chiral framework but different building block skeleton, beyond that for the basicity in the N-donor atoms, for rigidity and flexibility features. The N-N^∗ ligands act as chelating ligands leading a square planar geometry. The compounds [Pd(S,S-3)Cl₂] and [Pd(R,R-4)Cl₂] have been also characterised by X-ray diffraction. The rigidity and flexibility features of (S,S)-3 and (R,R)-4 ligands induce a different orientation of the trans-2,5-dimethylpyrrolidinyl moiety with respect to the pyridinyl and quinolinyl plane. This work shows that intrinsic rigidity and flexibility are not enough to define the ligand properties and to preview the effects that they induce on the reactivity of the metal complex.     

One step synthesis of aziridines by the Michael type addition of free sulfimides: Preparation and absolute configuration of optically active acylaziridines

The Michael type additions of diphenyl N-unsubstituted sulfimide (free sulfimide) to various electrophilic olefins were carried out. The reaction with cis- and trans-dibenzoylethylene, dimethyl-fumarate, dimethylmaleate, benzalacetophenone and benzalacetone gave mainly the corresponding trans-2-acylaziridines and trans-enaminoketones. However, phenyl vinyl sulfone or acrylonitrile afforded not the corresponding aziridine but diphenyl-N-2-cyano or N-2-phenylsulfonylethylsulfimide, a simple Michael adduct When optically active (+)-(R)-o-methoxyphenyiphenyl free sulfimide was treated with such an α,β-unsaturated carbonyl compound as benzalacetopbenone, an optically active 2-acylazindine, i.e., (-)-trans-2-benzoyl-3-phenylaziridine was obtained in ca 30% optical purity and its absolute configuration was assigned as (2R,3S) upon chemical transformation to the configuration-ally known 2-phenyl-2-benzoylamino-1-ethanol or by comparing its CD spectrum with that of (1R,2R)-1-phenyl-2-benzoyl-cyclopropane. Meanwhile, (-)-(S)-o-methoxyphenylphenyl free sulfimide was found to react with benzalacetophenone to afford (+)-trans-2-benzoyl-3-phenylaziridine of 25% optical purity. Effects of solvent and temperature on both die distribution of the products ratio and the optical yield were examined.     

Electrostatic forces that determine O,O-trans versus O,S-cis conformers in the aminated porphyrin complexes of Cd(N-NHCO-2-C4H3O-tpp)(OAc) and Cd(N-NHCO-2-C4H3S-tpp)(OAc)

Two new diamagnetic, mononuclear and aminated porphyrin complexes of O,O-trans-Cd (3-trans) and O,S-cis-Cd (4-cis) have been synthesized and characterized by ¹H, ¹³C NMR spectroscopy. The crystal structures of (acetato)(N-2-furancarboxamido-meso-tetraphenylporphyrinato)cadmium(II) [Cd(N-NHCO-2-C₄H₃O-tpp)(OAc); 3-trans] and (acetato)(N-2-thiophenecarboxamido-meso-tetraphenylporphyrinato)cadmium(II) [Cd(N-NHCO-2-C₄H₃S-tpp)(OAc); 4-cis] were determined. The coordination sphere around Cd²⁺ is a distorted square-based pyramid in which the apical site is occupied by a bidentate chelating OAc⁻ group for 3-trans and 4-cis. The plane of three pyrrole nitrogen atoms [i.e., N(1), N(2), N(4) for 3-trans and N(1), N(2), N(3) for 4-cis] strongly bonded to Cd²⁺ is adopted as a reference plane 3N. The N(3) and N(4) pyrrole rings bearing the 2-furancarboxamido (Fr) and 2-thiophenecarboxamido groups in 3-trans and 4-cis, respectively, deviate mostly from the 3N plane, thus orienting separately with a dihedral angle of 33.4° and of 31.0°. In 3-trans, Cd²⁺ and N(5) are located on different sides at 1.06 and −1.49 Å from its 3N plane, while in 4-cis, Cd²⁺ and N(5) are also located on different sides at 1.04 and −1.53 Å from its 3N plane. An attractive electrostatic interaction between the Cd²⁺ and O(4)⁻ atoms in furan stabilizes the O,O-trans conformer of 3. A repulsive electrostatic interaction between Cd²⁺ and S(1)⁺ destabilizes the O,S-trans conformer of 4. Both of these repulsive and the mutually attractive interactions between S(1)⁺ and O(3)⁻ atoms favor the O,S-cis rotamer of 4 both in the vapor phase and in low polarity solvents. NOE difference spectroscopy, HMQC and HMBC were employed for the unambiguous assignment of the ¹H and ¹³C NMR resonances of 3-trans and 4-cis in CDCl₃ at 20 and −50 °C.     

Reactivity of [trans-R2MoO(NNPhR′)(o-phen)] toward R′PhNNH2 and R′PhNNH3+Cl−, R=Me,Ph and R′=Me,Ph. X-ray structure of [trans-MeClMoO(NNPh2)(o-phen)]

The reactivities of [trans-R₂MoO(NNPhR′)(o-phen)], R=R′=Me (1); R=Me, R′=Ph (2); R=Ph, R′=Me (3); R=R′=Ph (4), toward (i) neutral 1,1-disubstituted hydrazines, R′PhNNH₂ and (ii) 1,1-disubstituted hydrazine hydrochlorides, R′PhNNH₂·HCl, R′=Me, Ph, were studied in acetonitrile. In the first case, no condensation reaction of the free oxo group was observed under different experimental conditions. In the second case, using a 1:1 precursor/hydrazine hydrochloride molar ratio, the oxo group was also unreactive, instead one methyl or phenyl group bonded to molybdenum was displaced as methane or benzene and was subsequently substituted by one chloride ligand affording complexes formulated as [trans-RClMoO(NNPhR′)(o-phen)], R=R′=Me (5); R=Me, R′=Ph (6); R=Ph, R′=Me, (7)·MeCN; R=R′=Ph, (8)·MeCN. Finally, when a 1:2 precursor/hydrazine hydrochloride molar ratio was used, both methyl and phenyl groups were substituted affording complexes formulated as [trans-Cl₂MoO(NNPhR′)(o-phen)], R′=Me (9), R=Ph (10). The new organometallic compounds were characterised by IR, UV–Vis and ¹H NMR spectroscopy while the crystal and molecular structure of 6 was determined by X-ray diffraction analysis.     

Codonocarpus alkaloids—IV : Synthesis of 2-methoxy-2′-ethoxy-4-[2-(tetramethylenecarbamoyl)ethyl]-5′-[2-(propylcarbamoyl)ethyl]diphenyl ether

Synthesis of the title compound was accomplished by coupling the iodonium bromide (3) of 4-ethoxybenzaldehyde with methyl hydroferulate (4) to 2-methoxy-2′-ethoxy-4-(methyl β-propionate)-5′-formyldiphenyl ether (5) which was converted to the pyrrolidinyl amide 6, and then the aryl aldehyde group was extended to a n-propyl β-propionamide unit via the Knoevenagel malonic acid reaction through the trans-cinnamic acid 7 followed by hydrogenation and amide formation with n-propylamine.     

Prostaglandin chemistry—IV : Microbiological kinetic resolution and asymmetric hydrolysis of 3,5-diacetoxycyclopent-1-ene

A 1:1 mixture of cis- and trans-3,5-diacetoxycyclopent-1-ene (1) was asymmetrically hydrolysed by baker's yeast to give trans-3(R)-acetoxy-5(R)-hydroxycyclopent-1-ene (R-2a) and S-predominant 3,5-dihydroxycyclopent-1-ene (3) accompanied by trans-3(R),5(R)-diacetoxycyclopent-1-ene (R-1a).The optical activities on the products were found to be dependent on the difference of the enzymatic hydrolytic rate among cis-, trans(S,S)- and trans(R,R)-3,5-diacetoxycyclopent-1-ene.The asymmetric hydrolysis was also investigated on wheat germ lipase, citrus acetyl esterase, and the lipase prepared from Aspergillus niger.     

Novel resolution of the anthracyclinone intermediate by the use of (2r, 3r)-(+)- and (2s, 3s)-(-).1,4-bis(4-chlorobenzyloxy)butane-2,3-diol: a simple and efficient synthesis of optically pure 4-demethoxydaunomycinone and 4-demethoxyadriamycinone

(±)-7-Deoxy-4-demethoxydaunomycinone((±)-3) was found to be cleanly resolved by forming a mixture of the diastereomereic acetals((-)-9and(+)-10 or(+)-9 and(-)-10)with the title vicinal-diol(+)-or ( )-5), affording optically pure (R)-( )-3. The resolving agents (( + )- and ( )-5) were readily synthesized from unnatural(2S,3S)-(-)-tartaric acid((-)-6)or D-(-)-mannitol and natural (2R,3R)-(+)-tartaric acid((+)6), respectively. The undesired enantiomer ((S)-(+ )-3) obtained by the optical resolution could be racemized by heating with trifluoromethanesulfonic acid in aq acetic acid. Optically pure (R)-3 was elaborated to optically pure (+)-4-demethoxydaunomycinone ((+)-2b) and (+)-demethoxyadriamycinone ((+)-2a) by featuring highly stereoselective ( ? 20:1) introduction of the OH group into the C₇-position as a key step.     

Enantioselective catalytic cyclopropanation of styrenes by copper complexes with chiral pinene-[5,6]-bipyridine ligands

Substituted mono- and bis-pinene-[5,6]-bipyridines are useful ligands in asymmetric copper-catalyzed cyclopropanation by styrenes. Copper complexes were prepared either in situ or prior to the reaction. The catalytic reaction of styrene with ethyl diazoacetate and Cu–11b yields ethyl trans-phenylcyclopropane carboxylate in >99% yield and 87% e.e. at 0°C. The corresponding cis-configured cyclopropane was produced with an e.e. of 90%. The cis/trans ratio is 22:78. Other ligands of this series are less effective. Various olefins were tested as substrates but exo-methylene olefins show the best results.     

Synthese et proprietes chimiques de deux diazoalcanes α-thiophosphores. observation d'un couplage 4jpp

Transfer of diazo and/or azide groups to the methylene of phosphine sulfides 1 Ph₂P(S) CH₂R, leads to the diazoalkanes Ph₂P(S)CN₂R 2b and 2c and azides Ph₂P(S)CHN₃R 3a and 3c in good yields. Thermolysis and photolysis in various media are studied. The 1,3-dipolar addition of 2c on trans dibenzoyléthylène and ethylfumarate is followed by Ph₂P(S) group migration. The corresponding carbenes give very complex reactions causing P-C bond breaking. New coupling constants ⁴J_PP and J_PC are observed.     

Crown-containing styryl dyes

Complexation of styryl dyes containing theN-phenylaza-15-crown-5 fragment (trans-2a,b) with Ca²⁺ ions in MeCN was studied. Unlike cationic dyetrans-2a, betainetrans-2b forms both complexes of 1∶1 stoichiometry and aggregates consisting of four dye molecules and one Ca²⁺ ion. Cation-induced aggregation was observed also for the analog of dyetrans-2b, which contains a dimethylamino group instead of an azacrown ether fragment (trans-3). Apparently, the interaction between a metal cation and sulfo groups of moleculestrans-2b ortrans-3 makes the main contribution to the stability of aggregates. The dependence of the stability of aggregates on the nature of the metal cation was studied.     

Octahedral bis(acetylide) and bis(diacetylide) complexes of ruthenium(II) with linear C2MC2 and C4MC4 chains: The first X-ray structures of the all trans bis(acetylides) Ru(CO)2(CCPh)2(PEt3)2 and Ru(CO)2(CCH)2(PEt3)2

Bis(acetylides) and bis(diacetylides) of ruthenium(II), trans-Ru(CO)₂(PEt₃)₂(CCR)₂ (1) (1a, R  Ph; 1b, R  ^tBu; 1c, R  SiMe₃; 1d, R  H) and trans-Ru(CO)₂(PEt₃)₂(CCC CR)₂ (2) (2a, R  SiMe₃; 2b, R  H) have been synthesized and characterised. The first single crystal X-ray analyses of these all trans-acetylides have revealed linear C₂RuC₂ chains in 1a and 1d.     

The preparation of some cyclic phosphonates and their use in olefin synthesis

The preparation and the use in olefin synthesis of two 5-membered cyclic phosphonates, 2-carbethoxy-methyl 4,5-dimethyle-2-oxo-1,3,2-dioxaphospholane (4b) and 2-cyanomethyl-4,5-dimethyl-2-oxo-1,3,2-diox-aphospholane (4c) and the 6-membered phosphonates, 2-carbalkoxymethyl-5,5-dimethyl-2-oxo-1,3,2-diox-aphosphorinanes (5a and 5b) and 2-cyanomethyl-5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinane (5c) are described. Reactions of 4b with aromatic and aliphatic aldehydes lead to preferential formation of cis-olefins. Reactions of the other cyclic phosphonates with aldehydes lead to various mixtures of cis and trans olefins.     

Stereochemistry of organophosphorus cyclic compounds—III : The stereospecific synthesis of cis- and trans-2-N-phenylamino-2-oxo-4-methyl-1,3,2-dioxaphosphorinans

On the basis of chemical transformations and spectroscopic data the cis- and trans-geometry was assigned to the previously reported diastereoisomeric 2-N-phenylamino-2-oxo-4-methyl-1,3,2-dioxaphosphorinans (1). The addition of phenyl azide to cyclic phosphite (3) as well as the reaction of the resulting adduct (4) with carbon disulphide or benzoic acid takes place with overall retention of configuration at the P-atom. The conformation of the 1,3,2-dioxaphosphorinanyl ring system in both cis- and trans-1 is suggested.     

Synthesis of syn- and anti-tricyclo [4.1.0.02,4] heptan-5-ones and related compounds

A convenient entry to both title compounds 1 and 2, as well as to cis- and trans-4-iodomethyl-bicyclo [3.1.0]-hexan-2-ones 3and 4 and to 4-methyl-bicyclo [3.1.0]-hex-3-en-2-one 5 involving base-promoted reactions of cis- and -trans-3,4-diiodomethylcyclopentanones 6 and 7 is reported, and the behaviour of 6 and 7 towards different bases. bfv40bp4761b     

Rh(II)-Catalyzed asymmetric carbene transfer with ethyl 3,3,3-trifluoro-2-diazopropionate

The asymmetric cyclopropanation of 1,1-diphenylethylene (2) with ethyl 3,3,3-trifluoro-2-diazopropionate (1) in the presence of chiral Rh(II) catalysts affords cyclopropane 3 with yields and enantioselectivities of up to 72 and 40%, respectively. Similar results are obtained for asymmetric cyclopropenation of hex-1-yne (4), although enantioselectivity is lower. The cyclopropanation of mono-substituted olefins (8a-8e) with 1 leads to cis/trans-mixtures of cyclopropanes 9a-9e with a maximum ee of 75% for 4-methoxystyrene (8c).     

Synthesis and structure of the heterotrinuclear chromium-palladium clusters (RC5H4CrCl)2-(μ3S)(μ-SCMe3)2Pd(PPh3) with ferromagnetic exchange interactions over the CrSCr system

Reactions of (RC₅H₄)₂Cr₂(SCMe₃)₂S(I, R = H; II, R = Me) with (PPh₃)₂PdCl₂ in benzene at 20°C gives trinuclear complexes (RC₅H₄)₂Cr₂Cl₂(μ₃-S)(μ-SCMe₃)₂Pd(PPh₃)(III, R = H; IV, R = Me). The structure of IV as a monobenzene solvate is established by an X-ray analysis (black-green triclinic crystals space group P$\text{1}$ with a = 11.403(4), b = 14.933(5), c = 14.131(5) Å, α = 99.13(3), β = 112.72(3), γ = 95.65(3)°, V = 2201.6 Å, Z = 2; IV·C₆H₆). The structure was solved by direct methods and refined in an anisotropic approximation to R = 0.046, R_w = 0.058 for 7643 reflections with I ? 2σ(I). In the molecule of IV metal atoms are separated by non-bonding distances (Cr … Cr 4.079(I), Cr … Pd 3.230(I) and 3.380(I) Å) but linked by the bridging tridentate sulphur atom (CrS 2.339(2) and 2.329(2), PdS 2.327(2) Å), and two SCMe₃ groups between Pd and Cr (CrS 2.396(2) and 2.403(2), PdS 2.350(2) and 2.381(2) Å, Cr?Pd 85.14(6) and 89.92(6)°). The Cl atoms are transferred from Pd to Cr atoms (CrCl 2.308(2) Å) and being terminally coordinated are in trans-positions to each other (as well as η-CH₃C₅H₄ rings) with respect to the Cr₂Pd plane. Cr atoms in III and IV exhibit ferromagnetic exchange interactions over the Cr?Cr system (+2J = 28 and 11 cm^?1, respectively).     

Efficient kinetic bioresolution of 2-nitrocyclohexanol

The kinetic bioresolution of 2-nitrocyclohexanol 1 was investigated by screening a range of hydrolases both for enantioselective transesterification and for enantioselective hydrolysis of the corresponding acetate. By appropriate choice of biocatalyst and conditions, both enantiomers of cis and trans 2-nitrocyclohexanol 1 can be accessed in enantiopure form.     

Synthesis of trans-[Re(NO)2-(Ph2PCH2CH2PPh2)2][BF4], a formal dinitrosyl complex of rhenium(-I) and its protic denitrosylation. X-Ray structure of trans-[ReF(NO)-(Ph2PCH2CH2PPh2)2][BF4]

Treatment of a THF solution of trans-[ReCl(N₂)(dppe)₂] (dppe = Ph₂PCH₂CH₂PPh₂) with NO, in the presence of Tl[BF₄], forms trans-[Re(NO)₂(dppe)₂][BF₄], a rare formal 20-electron d⁸-rhenium nitrosyl complex which, by reaction with HX (X = BF₄, Cl or HSO₄), gives trans-[ReF(NO)(dppe)₂][BF₄] (2) (the X-ray structure of which is reported) or trans-[ReX(NO)(dppe)₂]X (3, X = Cl or HSO₄), respectively, as well as nitrous oxide.     

Radical cyclization of homopropargylic bromomethyldimethylsilyl ethers. Evidence for a hetero-trans-cycloheptene intermediate

This communication describes our preliminary results on the radical cyclization of homopropargylic bromomethyldimethylsilyl ethers, an unknown reaction. With precursor 5a, only the very rare 7-endo-dig process was observed. The reduction of the resulting vinyl radical is not stereoselective and gives a cis/trans, 1.35:1 mixture of silaoxepan derivatives, as determined after a methyllithium treatment yielding olefins 11 and 12. This represents a new example of formation of a trans heterocyclic cycloheptene. With disubstituted precursor 5b, the system is less reactive and still no 6-exo-dig radical cyclization has been observed.