6-Chloro-2(2H)-pyranone: a new 2(2H)-pyranone synthon

6-Chloro-2(2H)-pyranone, which can be prepared in high yield from commercially available trans-glutaconic acid, undergoes facile Pd/Cu-catalyzed reaction with various 1-alkynes to give rise to the corresponding 6-(1-alkynyl)-2(2H)-pyranones in moderate to good yields. These last hitherto unknown compounds have been used as direct precursors to 6-alkyl- and 6-[(Z)-1-alkenyl]-2(2H)-pyranones.     

Regioselective biocatalytic hydrolysis of (E,Z)-2-methyl-2-butenenitrile for production of (E)-2-methyl-2-butenoic acid

Acidovorax facilis 72W nitrilase catalyzed the regioselective hydrolysis of (E,Z)-2-methyl-2-butenenitrile, producing only (E)-2-methyl-2-butenoic acid with no detectable conversion of (Z)-2-methyl-2-butenenitrile. (E)-2-Methyl-2-butenoic acid, produced in aqueous solution as the ammonium salt, was readily separated from (Z)-2-methyl-2-butenenitrile, and isolated in high yield and purity. The combination of nitrile hydratase and amidase activities of several Comamonas testosteroni strains were also highly regioselective for the production of (E)-2-methyl-2-butenoic acid from (E,Z)-2-methyl-2-butenenitrile.     

Novel (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles from (E)- and (Z)-3-styrylchromones: the unexpected case of (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles

An efficient synthetic method for the preparation of (E)- and (Z)-3(5)-(2-hydroxyphenyl)-4-styrylpyrazoles has been developed. The reaction of (E)- and (Z)-3-styrylchromones with hydrazine hydrate afforded the corresponding (E)- and (Z)-4-styrylpyrazoles, respectively, saved 4′-nitro-derivatives where both (E)- and (Z)-4′-nitro-3-styrylchromones afforded (E)-3(5)-(2-hydroxyphenyl)-4-(4-nitrostyryl)pyrazoles. The reaction mechanism for these transformations was discussed and the stereochemistry of all products was assigned by NMR experiments.     

N-Nitrosation of (E)-2-(benzylidene-amino)ethanols

Reaction of (E)-2-(benzylidene-amino)ethanol 2 with nitric oxide afforded an (E)-rotamer dominant mixture of (E)- and (Z)-N-nitroso-2-aryl-1,3-oxazolidine 3 at room temperature in good overall yields.     

Efficient synthesis of (Z)- and (E)-methyl 2-(methoxyimino)-2-phenylacetate

Direct oximation of 2-oxo-2-phenylacetate (3) gave the (Z)-methyl 2-(methoxyimino)-2-phenylacetate (1) in 71% yield, while the E oxime 2 was prepared from 3 in 65% yield via oxime isomerization of 2-(methoxyimino)-2-phenylacetic acid (5). Computational studies suggest that the isomerization of 5 is thermodynamically driven, while the direct oximation of ketoester 3 is kinetically controlled.     

Enantioselective synthesis of (1S,2S)-1,2-di-tert-butyl and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamines

An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a,b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1-p-tolylsulfonyl-4,5-di-tert-butyl-2-imidazolidinones 12 and 19 and 1-p-tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20, respectively. Finally, N-p-tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH)₂·8H₂O to achieve ring cleavage and to provide (1S,2S)-1,2-di-tert-butylethylenediamine 3 and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamine 4.     

Synthesis and dynamic nuclear magnetic resonance studies of the heterocyclic diphosphacyclopolysilanes, (PhP)2(SiMe2)n. Crystal and molecular structure of (PhP)2(SiMe2)3

The heterocyclic diphosphasilanes (PhP)₂(SiMe₂)_n(n - 2, 3, 4) were synthesized by the reactions of 1, 2-dilithium-1, 2-diphenyldiphosphide with α, ω-dichloropermethylpolysilanes Cl(SiMe₂)_nCl (n - 2, 3, 4). Stereochemical fluxionality in these compounds was examined by dynamic nuclear magnetic resonance. The¹H, ¹³C, ³¹P and²⁹Si NMR spectra are reported and discussed in terms of a phosphorus inversion mechanism. Values of the free energy of activation for phosphorous inversion are reported for (PhP)₂(SiMe₂)_n (n - 3, 4) and compared with related compounds.A single-crystal X-ray structure analysis has been carried out on (PhP)₂-(SiMe₂)₃. The material crystallizes in the monoclinic space groupP2_1/c with four molecules per unit cell. The cell dimensions area - 12.526(11)A?, b - 11.828(10)A?, c - 15.412(7)A?and β - 103.56(6)°. The molecule exists in thedl (trans) form with the five-membered ring significantly twisted. The angle between the phosphorus-phosphorus bond and the plane of the three silicon atoms is 42.9°.     

Improved syntheses of Ru(CO)2 (O3SCF3)2 (bidentate) complexes and their conversion into new [Ru(CO)2 (bidentate)2]2+ complexes

Reaction of the complexes Ru(CO)₂Cl₂L [L = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen)] with trifluoromethanesulphonic acid under carefully controlled conditions yields Ru[cis-(CO)₂] [cis-(O₃SCF₃)₂] (bidentate complexes. From reactions of the trifluoromethanesulphonates with the appropriate bidentate ligands, the new complexes [cis-Ru(CO)₂-L(L′)]²⁺ (L as above; L′ = 4,4′-dimethyl-2,2′-bipyridyl or 4,4′-diisopropyl-2,2′-bipyridyl) as well as the known [_cis-Ru(CO)₂L₂]²⁺ and [cis-Ru(CO)₂bpy(phen)]²⁺ have been prepared.     

Synthesis and absolute configuration of two diastereoisomeric (1R,2S,3R)-and (1S,2S,3R)-2-amino-1-(2-furyl)-1,3-butandiols

The synthesis of (1R, 2S, 3R) and (1S, 2S, 3R)-2-(N-benzoylamino)-1-(2-furyl)-1, 3-butandiols (15) and (16) from D-threonine is described. The assignment of absolute configuration of the newly formed asymmetric center at C-1 was based on the ¹H-NMR spectra of O-isopropylidene derivatives 17 and 18.     

Synthesis, characterization and electroluminescence of B(III) compounds: BPh2(2-(2-quinolyl)naphtho[b]imidazolato) and BPh2(2-(2-quinolyl)benzimidazolato)

Two novel luminescent boron compounds, BPh₂(2-(2-quinolyl)naphtho[b]imidazolato) (1) and BPh₂(2-(2-quinolyl)benzimidazolato) (2), have been synthesized by the reactions of triphenylboron with appropriate ligands, 2-(2-quinolyl)naphtho[b]imidazole (QNI) and 2-(2-quinolyl)benzimidazole (QBI), respectively. The structure of 1 was determined by single crystal X-ray diffraction, while 2 by spectroscopic methods. The structure of 1 reveals that the boron center is four coordinated. Several types of OLED possessing different colors were fabricated by using 1 as emitter. For the three-layer OLED with the structure ITO/NPB/2/Alq₃/Mg-Ag, an emission band covering the whole visible region from 400 to 750 nm with the maximum brightness of 320 cd/m² was observed, indicating a perfect white light OLED (CIE = 0.33, 0.37). Compounds 1 and 2 form a new family of organometallic emitting materials which could be of interest for practical application.     

Efficient synthesis of new 1-alkyl(aryl)-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrol-2(5H)-ones

The synthesis of 1-alkyl(aryl)-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrol-2(5H)-ones 5, 6a-d from 1-alkyl(aryl)-4-bromo-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrolidin-2-ones 3, 4a-d is reported. The 1-alkyl(aryl)-4-bromo-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrolidin-2-ones 3, 4a-d were obtained from regiospecific bromination of 1-alkyl(aryl)-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrolidin-2-ones 1, 2a-d with molecular bromine. The NMR and X-ray diffraction data showed that 1-alkyl(aryl)-5-(3,3,3-trihalo-2-oxopropylidene)-1H-pyrrolidin-2-ones were brominated at 4-position in the pyrrolidin-2-one ring.     

Reactions of (1R,2S)-1,2-di(2-furyl)-1,2-di(3-guaiazulenyl)ethane and (1R,2S)-1,2-di(3-guaiazulenyl)-1,2-di(2-thienyl)ethane with tetracyanoethylene (TCNE) in benzene: comparative studies on the products and their spectroscopic properties

Reactions of the title meso forms, (1R,2S)-1,2-di(2-furyl)-1,2-di(3-guaiazulenyl)ethane (1) and (1R,2S)-1,2-di(3-guaiazulenyl)-1,2-di(2-thienyl)ethane (2), with a two molar amount of TCNE in benzene at 25 °C for 5 h (for 1) and 48 h (for 2) under oxygen give new compounds, 2,2,3,3-tetracyano-4-(2-furyl)-8-isopropyl-6-methyl-1,4-dihydrocyclohepta[c,d]azulene (3) and 2,2,3,3-tetracyano-8-isopropyl-6-methyl-4-(2-thienyl)-1,4-dihydrocyclohepta[c,d]azulene (4), respectively, in 74 and 21% isolated yields. Comparative studies on the above reactions as well as the spectroscopic properties of the unique products 3 and 4, possessing interesting molecular structures, are reported and, further, a plausible reaction pathway for the formation of these products is described.     

Introduction of a planar chirality onto steroid substrates: synthesis of (S) and (R)-2′-formylcymantrenyl-17α-ethynylestradiols using (S) and (R)-1-formyl-2-iodo-cymantrenes

We report the synthesis and characterisation of (S) and (R)-2′-formylcymantrenyl-17α-ethynylestradiol synthesized using the Sonogashira cross-coupling reaction between optically pure (S) and (R) 1-formyl-2-iodo cymantrenes and ethynylestradiol. (S) and (R) 1-formyl-2-iodo cymantrenes were obtained from the same precursor: (2R,4R)-4-(methoxymethyl)-2-cymantrenyl-1,3-dioxane.     

Synthesis,spectroscopic and structural investigation of Zn(NCS)2(nicotinamide)2 and [Hg(SCN)2(nicotinamide)]n

Zinc(II) and mercury(II) thiocyanate complexes with nicotinamide, bis(nicotinamide-N)-bis(thiocyanato-N)zinc(II) (1) and catena-[nicotinamide-N-(μ-thiocyanato-S,N)(thiocyanato-S)mercury(II)] (2), have been prepared and characterized by spectroscopic, thermal and X-ray crystallographic methods. The vibrational bands of diagnostic value are compared to the values of the free ligand and the data are in good correlation with the X-ray results. Centrosymmetrical hydrogen bonded dimers are found, R₂²(10) in 1 and R₂²(8) in 2.     

Synthesis of (+)-(1S,2R) and (−)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids

(+)-(1S,2R) and (−)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids have been prepared in >97% ee and in 33% and 20% overall yields starting from a single, chiral, bicyclic compound perceived as a chiral uracil equivalent. Construction of the cyclobutane ring is achieved via a [2+2] photocycloaddition reaction of this chiral precursor with ethylene.     

Carbonyl complexes of manganese(I) with chelating phosphino-alkyl or -acyl ligands. Crystal and molecular structure of [Ph2PCH2CH2(O)CMn(CO)2(dppm)l

The phosphine Ph₂PCH₂CH₂Cl reacts with fac-[XMn(CO)₃(dppm)] (X = Cl or Br) in refluxing toluene to give the complexes cis,cis-[XMn(CO)₂(dppm)(Ph₂PCH₂CH₂Cl)] (I). Treatment of those species with Na amalgam in THF leads to the alkyl complex [Ph₂$\text{PCH}{}_2\text{CH}{}_2\text{M}$n(CO)₂(dppm)] (II), which does not react with CO under normal conditions but can be converted into cis,cis-[ClMn(CO)₂(dppm)(PPh₂Et)] by reacting with HCl (g) in ether. If the reduction of I with Na/Hg is carried out in the presence of CO the compound cis-[Ph₂$\text{PCH}{}_2\text{CH}{}_2\text{(O)CM}$n(CO)₂(dppm)] (III) is obtained. The latter has also been prepared directly from fac-[BrMn(CO)3(dppm)], Ph₂PCH₂CH₂Cl, and Na/Hg in THF, and characterized by X-ray crystallography. The crystals are monoclinic, space group P2₁/n; refinement gave R = 0.053 for 2593 reflections with I ? 2.5σ(I). The reaction of the complex fac-[O₃ClOMn(CO)₃(dppm)] with Ph₂PCH₂CH₂Cl in Cl₂CH₂ gives the salt fac-[Mn(CO)₃(dppm)(Ph₂PCH₂CH₂Cl)]ClO₄ which isomerizes to mer-[Mn(CO)₃(dppm)(Ph₂PCH₂CH₂Cl)]ClO₄ in boiling butanol. Both cationic carbonyl complexes give the acyl species III upon reduction with Na amalgam.     

N-arylammonio- and N-pyridinium-substituted derivatives of dodecahydro-closo-dodecaborate(2-)

We report two methods for preparing N-arylammonio, N-pyridyl and N-arylamino dodecaborates: heating of the tetrabutylammonium salt of dodecahydro-closo-dodecaborate(2-) with aryl and pyridyl amines, or nucleophilic attack of [closo-B₁₂H₁₁NH₂]²⁻ on a strongly deactivated aromatic system. With aryl amines we obtained [1-closo-B₁₂H₁₁N(R¹)₂C₆H₅]⁻ (R¹ = H, CH₃). With 4-(dimethylamino)pyridine, [1-closo-(B₁₂H₁₁NC₅H₄)-4-N(CH₃)₂]⁻, with a bond between the boron and the pyridinium nitrogen, was obtained. A presumable mechanism for this kind of reactions is reported. By nucleophilic substitution, two products, [1-closo-(B₁₂H₁₁NHC₆H₃)-3,4-(CN)₂]²⁻ and [1-closo-(B₁₂H₁₁NHC₆H₂)-2-(NO₂)-4,5-(CN)₂]²⁻, were formed with 4-nitrophthalonitrile and 1-chloro-2,4-dinitrobenzene gave [1-closo-(B₁₂H₁₁NHC₆H₃)-2,4-(NO₂)₂]²⁻. For [1-closo-B₁₂H₁₁N(CH₃)₂C₆H₅]⁻ and [1-closo-(B₁₂H₁₁NHC₆H₃)-2,4-(NO₂)₂]²⁻ single crystal X-ray structures were obtained.     

Efficient synthesis of (R)- and (S)-3-octanol, (R)-2-dodecanol, (R)-2-methyl-4-heptanol and (R)-2-methyl-4-octanol: the pheromones of Myrmica scabrinodis, Crematogaster castanea, C. liengmei, C. auberti and Metamasius hemipterus

A simple and efficient synthesis of optically active insect pheromones, such as (R)- and (S)-3-octanol, (R)-2-dodecanol, (R)-2-methyl-4-heptanol and (R)-2-methyl-4-octanol starting from non-racemic β-hydroxy sulfides has been established.     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

A single-helix coordination polymer with mixed ligands [Zn2(phen)2(e,a-cis-1,4-chdc)2(H2O)2]n (phen=1,10-phenanthroline; chdc=cyclohexanedicarboxylate)

A coordination polymer with mixed ligands [Zn₂(phen)₂(e,a-cis-1,4-chdc)₂(H₂O)₂]_n (chdc=cyclohexanedicarboxylic acid; phen=1,10-phenanthroline) was prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, TG analysis, and single-crystal X-ray diffraction analysis. X-ray crystal structural analyses reveal that 1 and 2 are isomorphic and belong to the monoclinic system. C₄₀H₃₆Zn₂N₄O₁₀, P2₁/c, a=10.084(2) Å, b=8.9072(18) Å, c=20.276(4) Å, β=99.92(3)°, V=1793.9(6) Å³, Z=1. In the structures of 1, the 1,4-chdc ligand possesses only one kind of e,a-cis-conformation although there are both cis- and trans-conformations in the raw material. Two oxygen atoms of one carboxyl in 1,4-chdc ligand and another oxygen atom of contraposition carboxyl link adjacent Zn atoms into an infinite 1D zigzag chain. The most attractive structural feature of 1 is that it exhibits an infinite chiral chain-like structure with 2₁ helices along the b-axis. In addition, the right- and left-handed chains are alternate. Meanwhile, the adjacent chains of 1 is linked via hydrogen bonds into 2D network structures, which further form 3D frameworks via π-π interactions of 1,10-phen.