New tertiary phosphines from cinnamaldehydes and diphenylphosphine.

A 1:1 hydrophosphination of the olefinic bond of cinnamaldehyde (and substituted ones) with Ph2PH, under argon using neat reagents, gives quantitative formation of the new tertiary phosphines Ph2PCH(Ar)CH2CHO (2) as racemic mixtures (Ar = Ph, p-tol, and p-OMe-C6H4). alpha-Methylcinnamaldehyde similarly affords Ph2PCH(Ph)CH(Me)CHO, but as a mixture of diastereomers with predominantly S,S- and R,R-chirality [diastereomeric ratio (dr) approximately 20]. In a 2:1 reaction of Ph2PH with cinnamaldehyde, hydrophosphination of both the C=C and C=O bonds takes place to give the diphosphine derivative Ph2PCH(Ph)CH2CH(OH)PPh2 (3) as a diastereomeric mixture with dr approximately 2.

Interaction of tertiary phosphines with lignin-type, alpha,beta-unsaturated aldehydes in water.

To learn more about the bleaching action of pulps by (hydroxymethyl)phosphines, lignin chromophores, such as the alpha,beta-unsaturated aromatic aldehydes, sinapaldehyde, coniferylaldehyde, and coumaraldehyde, were reacted with the tertiary phosphines R2R'P [R = R' = Me, Et, (CH2)3OH, iPr, cyclo-C6H11, (CH2)2CN; R = Me or Et, R' = Ph; R = Ph, R' = Me, m-NaSO3-C6H4] in water at room temperature under argon. In all cases, initial nucleophilic attack of the phosphine occurs at the activated C=C bond to form a zwitterionic monophosphonium species. With the phosphines PR3 [R = Me, Et, (CH2)3OH] and with R2R'P (R = Me or Et, R' = Ph), the zwitterion undergoes self-condensation to give a bisphosphonium zwitterion that can react with aqueous HCl to form the corresponding dichloride salts (as a mixture of R,R- and S,S-enantiomers); X-ray structures are presented for the bisphosphonium chlorides synthesized from the Et3P and Me3P reactions with sinapaldehyde.

Synthesis and X-ray structures of water-soluble tris(hydroxymethyl)phosphine complexes of rhodium(I).

The water-soluble Rh(I)-THP complexes: RhCl(1,5-cod)(THP) (), [Rh(1,5-cod)(THP)(2)]Cl (), RhCl(THP)(4) (), and trans-RhCl(CO)(THP)(2) () have been synthesized and characterized, where THP = P(CH(2)OH)(3); - are the first potentially useful entries into Rh(I)-THP chemistry, while and are the first structurally characterized Rh(I)-THP complexes.

Formation of a phosphine-phosphinite ligand in RhCl(PRR'2)[P,P-R'(R)POCH2P(CH2OH)2] and R'H from cis-RhCl(PRR'2)2[P(CH2OH)3] via P-C bond cleavage.

Reaction of RhCl(1,5-cod)(THP), where THP = P(CH(2)OH)(3), with several PRR'2 phosphines (R = or not equal R') generates, concomitantly with R'H, the derivatives RhCl(PRR'(2))[P,P-R'(R)POCH(2)P(CH(2)OH)(2)] in two isomeric forms. The hydrogen of the hydrocarbon co-product derives from a THP hydroxyl group which becomes an 'alkoxy' group at the residual PRR' moiety, this resulting in the P,P-chelated R'(R)POCH(2)P(CH(2)OH)(2) ligand. One of the isomers of the PPh(3) system, cis-RhCl(PPh(3))[P,P-P(Ph)(2)OCH(2)P(CH(2)OH)(2)], was structurally characterized (cis refers to the disposition of the P atoms with Ph substituents).

Redox-active iron-containing polymers: synthesis and anionic polymerization of a C-ferrocenyl-substituted phosphaalkene.

The addition polymerization of a ferrocenyl-substituted P[double bond]C bond leads to new redox-active polymers with functional ferrocene and phosphine moieties.

Synthesis and structures of novel luminescent bent acenedithiophenes.

1,4-dithienyl-2,5-divinylbenzenes are readily available compounds that undergo oxidative photocyclization to afford bent anthradithiophenes (BADTs). The new parent and didodecyl-functionalized derivatives have been structurally characterized, and their absorption and emission spectra are reported.

New side-on bound dinitrogen complexes of zirconium supported by an arene-bridged diamidophosphine ligand and their reactivity with dihydrogen.

A new dinitrogen complex, deep blue-green {[NPN]*Zr(THF)}(2)(mu-eta(2):eta(2)-N(2)) ([NPN]* = {[N-(2,4,6-Me(3)C(6)H(2))(2-N-5-MeC(6)H(3))](2)PPh}), was prepared in high yield by the reduction of [NPN]*ZrCl(2) with 2.2 equiv of KC(8) in THF under N(2). The solid-state molecular structure shows that N(2) is strongly activated (N-N bond length: 1.

Synthesis, characterization, and metal coordinating ability of multifunctional carbohydrate-containing compounds for Alzheimer's therapy.

Dysfunctional interactions of metal ions, especially Cu, Zn, and Fe, with the amyloid-beta (A beta) peptide are hypothesized to play an important role in the etiology of Alzheimer's disease (AD). In addition to direct effects on A beta aggregation, both Cu and Fe catalyze the generation of reactive oxygen species (ROS) in the brain further contributing to neurodegeneration. Disruption of these aberrant metal-peptide interactions via chelation therapy holds considerable promise as a therapeutic strategy to combat this presently incurable disease.

Solid-state compounds of stereoisomers: cis and trans isomers of 1,2-cyclohexanediol and 2,3-tetralindiol.

The phases of 1,2,3,4-tetrahydro-2,3-naphthalenediol (or 2,3-tetralindiol) and of 1,2-cyclohexanediol have been investigated. The structure of a very stable 1:1 compound (or co-crystal) of the cis and trans isomers of 2,3-tetralindiol, the existence of which has been known for nearly a century, has finally been determined. No evidence of any analogous compound between the cis and trans isomers of 1,2-cyclohexanediol has been found.

Strongylophorine-26, an inhibitor of cancer cell Invasion: SAR revealed by synthesis of analogues.

The absolute configuration of strongylophorine-26 (1) was determined to be 4S, 5R, 8R, 9S, 10S, 13S, 14S by single-crystal X-ray diffraction analysis of the derivative 7 prepared from the co-occurring metabolite strongylophorine-8 (4) and chemical interconversion to the bislactone 8. Synthetic analogues (+)- and (-)-3 have been prepared in order to explore the structure-activity relationship for the anti-invasion pharmacophore of stronglylophorine-26. These studies revealed the unanticipated importance of the A ring lactone moiety for the anti-invasion activity of 1.

Janus-AT bases: synthesis, self-assembly, and solid state structures.

The high yielding synthesis of heterocycles with defined H-bond accepting and donating capabilities provides for the design of self-assembling structures and specific recognition of biological targets. Herein we report the syntheses and solid-state structures of three self-complementary uracil/thymine derivatives where each presents the standard ADA face inherently complementary to adenine and a synthetically appended DAD face complementary to uracil/thymine. These heterocycles, which have never before been reported or characterized, represent diaminopurine-uracil/thymine hybrids that, in two of the three cases, relate to previously reported heterocyclic hybrids of G and C.

Platinum(II)-catalyzed cyclizations forming quaternary carbon centers, using enesulfonamides, enecarbamates, or enamides as nucleophiles.

Cyclic enesulfonamides, enecarbamates, or enamides tethered to an alkyne cyclize readily with use of platinum(II) chloride. This reaction generates quaternary-substituted carbon centers within simple spiro-fused or more complex tri- and tetracyclic heterocyclic ring systems. The yields for this process range from 50% to 83%.

trans-Carbonyl-chloridobis(ethyl-diphenyl-phosphine-κP)rhodium(I).

The title compound, [RhCl(C(14)H(15)P)(2)(CO)], crystallizes with two almost identical mol-ecules in the asymmetric unit. The mol-ecules have the Rh(I) atom in a square-planar geometry. The crystal structure involves intermolecular C-H⋯O hydrogen bonds.

Formazans as beta-diketiminate analogues. Structural characterization of boratatetrazines and their reduction to borataverdazyl radical anions.

Formazans react with boron triacetate to produce boratatetrazines, which can be reduced to yield borataverdazyl radical anions--the first boron containing verdazyl radicals.

Exiguamine A, an indoleamine-2,3-dioxygenase (IDO) inhibitor isolated from the marine sponge Neopetrosia exigua.

Exiguamine A (1), a hexacyclic alkaloid with an unprecedented skeleton, has been isolated from the marine sponge Neopetrosia exigua collected in Papua New Guinea. The structure of exiguamine A (1) was elucidated by a combination of spectroscopic analysis and single-crystal X-ray diffraction analysis. Exiguamine A (1) has a Ki of 210 nM for inhibition of indoleamine-2,3-dioxygenase (IDO) in vitro, making it one of the most potent IDO inhibitors known to date.

An easy-to-use, regioselective, and robust bis(amidate) titanium hydroamination precatalyst: mechanistic and synthetic investigations toward the preparation of tetrahydroisoquinolines and benzoquinolizine alkaloids.

Amidate-supported titanium amido complexes are efficient and regioselective precatalysts for intermolecular hydroamination of terminal alkynes with primary amines. The synthesis and characterization of the first bis(amidate)-supported titanium-imido complex is reported. Its role as the active catalytic species is suggested in the course of product distribution studies using deuterated substrates.

Concurrent N-H and alpha-C-H bond activations of pyrrolidine and piperidine under ambient conditions by 18e tungsten allyl nitrosyl complexes.

18e Cp*W(NO)(CH2CMe3)(eta3-allyl) complexes effect concurrent N-H and alpha-C-H bond activations of cyclic, saturated amines under mild conditions, the conversions involving pyrrolidine being shown. In a similar manner, treatment of Cp*W(NO)(CH2CMe3)(eta3-3,3-Me2C3H3) with piperidine at room temperature results in the clean formation of the alkyl amido complex, Cp*W(NO)(CH2CMe3)(NC5H9CMe2CHCH2).

Inner-sphere two-electron reduction leads to cleavage and functionalization of coordinated dinitrogen.

Activation of molecular nitrogen by transition metal complexes is an area of current interest as investigations using the inert N2 molecule to produce higher-value organonitrogen compounds intensify. In an attempt to extend the addition of hydride reagents E-H (where E = BR2, AlR2, and SiR3) to the dinitrogen complex ([NPN]Ta)2(mu-H)2(mu-eta1:eta2-N2) [1; where NPN = (PhNSiMe2CH2)2PPh], the reaction with zirconocene chlorohydride, [Cp2Zr(Cl)H]x, was examined. The crystalline product formed in 35% yield was determined to be ([NP(N)N]Ta)(mu-H)2(mu-N)(Ta[NPN])(ZrCp2) (2) in which the coordinated N2 has been cleaved to form a phosphinimide bridging between Ta and Zr and a triply bridging nitride.

Ruthenium(III) maltolato-nitroimidazole complexes: synthesis and biological activity.

The Ru(III) metronidazole-maltolato and -ethylmaltolato complexes, trans-[RuL(2)(metro)(2)]CF(3)SO(3) (L=ma (1a) or etma (1b)), have been synthesized and tested for potential anti-tumour activity against the human breast cancer cell line MDA-MB-435S using a so-called MTT assay in phosphate-buffered saline; ma=3-hydroxy-2-methylpyran-4-onato, etma=2-ethyl-3-hydroxypyran-4-onato, metro=2-methyl-5-nitro-1H-imidazole-1-ethanol (metronidazole); MTT=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The complexes exhibit lower IC(50) values than our previously reported Ru(III) tris-maltolato and -ethylmaltolato complexes [D.C.

Glucosamine conjugates of tricarbonylcyclopentadienyl rhenium(I) and technetium(I) cores.

To obtain a 99mTc glucose conjugate for imaging, double-ligand transfer (DLT) and related reactions were examined for the preparation of CpM(CO)3 (Cp = cyclopentadienyl; M = Re, Tc) complexes with pendant carbohydrates at Cp. Tricarbonyl{N-(1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-beta-D-glucopyranose)cyclopentadienyl carboxamide}rhenium(I) (1a) and tricarbonyl{N-(2-amino-2-deoxy-beta-D-glucopyranose)cyclopentadienyl carboxamide}rhenium(I) (2a) were prepared. The compounds were fully characterized by mass spectrometry, elemental analysis, IR, and NMR spectroscopy.

Phosphorus copies of PPV: pi-conjugated polymers and molecules composed of alternating phenylene and phosphaalkene moieties.

A new class of pi-conjugated macromolecule, poly(p-phenylenephosphaalkene) (PPP), is reported. PPPs are phosphorus analogues of the important electronic material poly(p-phenylenevinylene) (PPV) where P=C rather than C=C bonds space phenylene moieties. Specifically, PPPs [-C(6)R(4)-P=C(OSiMe(3))-C(6)R'(4)-C(OSiMe(3))=P-](n)() (1: R = H, R' = Me; 11: R = Me, R' = H) were synthesized by utilizing the Becker reaction of a bifunctional silylphosphine, 1,4-C(6)R(4)[P(SiMe(3))(2)](2), and diacid chloride 1,4-C(6)R'(4)[COCl](2).

Scope and limitations of the base-catalyzed phospha-peterson P=C bond-forming reaction.

Phosphaalkenes (MesP=CRR': R = R' = Ph (1a); R = R' = 4-FC6H4 (1b); R = Ph, R' = 4-FC6H4 (1c); R = R' = 4-OMeC6H4 (1d); R = Ph, R' = 4-OMeC6H4 (1e); R = Ph, R' = 2-pyridyl (1f)) are prepared from the reaction of MesP(SiMe3)2 and O=CRR' in the presence of a trace of KOH or NaOH. The base-catalyzed phospha-Peterson reaction is quantitated by NMR spectroscopy, and isolated yields of phosphaalkene between 40 and 70% are obtained after vacuum distillation and/or recrystallization. The asymmetrically substituted phosphaalkenes (1c, 1e, 1f) form as 1:1 mixtures of E and Z isomers; however, X-ray crystallography reveals that the E isomers crystallize preferentially.

Luminescence of ruthenium halide complexes containing a hemilabile phosphine pyrenyl ether ligand.

A series of Ru(II) complexes, tcc-RuX2(POC4Pyr-P,O)2 (X = Cl (3), Br (4), I (5)), containing the hemilabile phosphine pyrenyl ether ligand 4-{2-(diphenylphosphino)phenoxy}butylpyrene (POC4Pyr (1)) are reported. The synthesis and spectroscopic properties of both the ligand, POC4pyr (1), and ligand oxide, P(=O)OC4pyr 2, and the solid-state structure of 1 are reported. Complexes 3-5 react rapidly with CO to give complexes ttt-RuX2(CO)2(POC4pyr-P)2 (X = Cl (6), Br (7), I (8)).

S,S-1,2-Dicyclohexylethane-1,2-diol and its racemic compound: a striking exception to Wallach's rule.

The structures of enantiopure S,S-1,2-dicyclohexylethane-1,2-diol and its racemic compound (rac-S,S-1,2-dicyclohexylethane-1,2-diol) have been determined at 295 and 173 K. The crystals of the enantiopure material are more than 4% denser than the crystals of the racemic compound, but the melting points indicate that the crystals of the less dense racemic compound are considerably more stable than those of the racemic conglomerate. This apparent exception to the correlation of crystal density and melting point is explained.