2-chloro-(4R,5R)-bis[(1R,2S,5R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane: a practical chiral pool-derived reagent for determining enantiomeric purity of alcohols

2-Chloro-(4 R,5 R)-bis[(1 R,2 S,5 R)-menth-1-yloxycarbonyl)]-1,3,2-dioxaphospholane is a practical reagent for reliably determining enantiomeric purity of chiral alcohols via (31)P NMR spectroscopy. The compound is available as a crystalline solid on a 20 g scale from PCl 3 and bis[(1 R,2 S,5 R)-menth-1-yl] tartrate. It is comparatively inert toward spontaneous hydrolysis under conventional laboratory conditions but undergoes quantitative substitution of alkoxide for chloride if treated with a chiral alcohol. Nonequivalent (31)P NMR signals of diastereomeric 2-alkoxy-1,3,2-dioxophospholanes were dispersed by approximately 1.4-0.1 ppm. The associated integral ratios reflected enantiomeric purities of preweighted samples of ( R)- and ( S)-1-phenylethanol, (+)- and (-)-menthol, and a set of primary, secondary, and tertiary alcohols with a precision of +/-0.4-1.0%.     

Efficient and beta-Stereoselective Synthesis of 4(5)-(beta-D-Ribofuranosyl)- and 4(5)-(2-Deoxyribofuranosyl)imidazoles(1)

A synthetic route to 4(5)-(beta-D-ribofuranosyl)imidazole (1), starting from 2,3,5-tri-O-benzyl-D-ribose (5), was developed via a Mitsunobu cyclization. Reaction of 5 with the lithium salt of bis-protected imidazole afforded the corresponding 5-ribosylimidazole 7RS. Hydrolysis of 7RS gave a 1:1 mixture of diol isomers 8R and 8S having an unsubstituted imidazole. Mitsunobu cyclization of the mixture 8RS using N,N,N',N'-tetramethylazodicarboxamide and Bu(3)P exclusively afforded benzylated beta-ribofuranosyl imidazole 9beta in 92% yield, accompanied by alpha-anomer 9alpha, in a ratio of 26.3:1. The configuration of 9beta was established by X-ray crystallography of ethoxycarbonyl derivative 10beta. Reductive debenzylation of 9beta over Pd/C was carried out, and the synthesis of 1 was attained from starting 5 in four steps and 87% overall yield. This synthetic methodology was extended to the synthesis of 4(5)-(2-deoxy-beta-D-ribofuranosyl)imidazole (2). Mitsunobu cyclization of a 1:1 mixture of the corresponding diol isomers 14RS produced 15beta and 15alpha in a ratio of 5.4:1. The synthesis of 2 was attained in a 59% overall yield from the starting 3,5-di-O-benzyl-2-deoxy-D-ribose (12). beta-Stereoselective glycosylation in the key step is discussed and explained by intramolecular hydrogen bonding between an NH in the imidazole and the oxygen functional group in the sugar moiety.     

Synthesis of a C(29)-C(51) subunit of spongistatin 1 (Altohyrtin A) starting from (R)-3-benzyloxy-2-methylpropan-1-ol

A protected C(29)-C(51) subunit ((+)-38) of spongistatin 1 has been obtained. Key steps involve the aldol condensation of (3S, 4R)-3-methyl-7-[(p-methoxybenzyl)oxy]-4-[(triethylsilyl)oxy]octan- 2-o ne ((-)-6) with (tert-butyl)dimethylsilyl 4-deoxy-2, 3-di-O-(methoxymethyl)-4-methyl-6-O-(tert-butyl)dimethylsilyl)-bet a-D -glycero-L-gluco-heptodialdo-1,5-pyranoside ((+)-7) and a C-glycosidation of (4R,7R&S,E)-7, 8-dichloro-2-methylidene-1-(trimethylsilyl)oct-5-en-4-yl p-methoxybenzoate (16). Aldehyde (+)-7 was derived from (R)-3-benzyloxy-2-methylpropan-1-ol ((+)-10) in 13 formal steps but requiring the isolation of five intermediate products only. The longest linear synthetic scheme converts (+)-10 into (+)-38 in 2% overall yield (isolation of 11 intermediate products).     

Synthesis of the optical isomers of 4-[1-(4-tert-butylphenyl)-2-oxo- pyrrolidine-4-yl]methyloxybenzoic acid (S-2) and their biological evaluation as antilipidemic agent

The enantiomers of (+/-)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidine- 4-yl]methyloxybenzoic acid (S-2), a new antilipidemic agent having dual action on the plasma triglyceride (TG) and cholesterol (Cho) lowering effects, were prepared via separation by Chiralcel OJ column chromatography of their methyl ester and also by the same method as the described racemate's synthesis from optically active 1-(4-tert-butylphenyl)-2-oxo-pyrrolidine-4-carboxylic acid respectively. These optically active carboxylic acids were prepared by the resolution of diastereomeric N-[(S)-(-)-[4-methyl-(alpha-methyl)benzyl]]-1-(4-tert-butylphenyl)-2-oxo - pyrrolidine-4-carboxyamide using silica gel column chromatography, followed by deamination with N2O4. The absolute configurations for the enantiomers of S-2 were indirectly determined using X-ray analysis of the 4-bromo-2-fluorobenzamide of the (+)-4-[1-(4-tert-butylphenyl)-2- oxo-pyrrolidine-4-yl]-methyloxybenzoic acid. S-2 and its enantiomers showed an essentially equipotent activity on the fatty acid- and sterol-biosynthesis inhibition in vitro. On the other hand, in the in vivo activity, (S)-(+)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidine- 4-yl]methyloxybenzoic acid (S-2E) was superior in the lowering abilities of the plasma TG and phospholipid(PL) and was chosen as a candidate for a novel antilipidemic agent. The difference in the in vivo activity among S-2 and its enantiomers was explained from the pharmacokinetics after administration p.o.     

Synthesis and selected transformations of 1-(5-methyl-1-aryl-1H-1,2,3-triazol-4-yl)ethanones and 1-[4-(4-R-5-methyl-1H-1,2,3-triazol-1-yl)phenyl]ethanones

By cycloaddition of arylazides to acetylacetone are obtained derivatives of 1,2,3-triazole. In the reaction of 1-[5-methyl-1-(R-phenyl)-1H-1,2,3-triazol-4-yl] ethanones (IIa–IIe) and 1-[4-(4-R-5-methyl-1H-1,2,3-triazol-1-yl)phenyl] ethanones (VIIa-VIIe) with isatin are obtained 2-[1-(R-phenyl)-5-methyl-1H-1,2,3-triazol-4-yl]-4-quinolinecarboxylic acids (IIIa–IIIe) and 2-[4-(4-R-5-methyl-1H-1,2,3-triazol-1-yl)phenyl] -4-quinolinecarboxylic acids (IXa, IXb), respectively. We found that 1-[5-methyl-1-(R-phenyl)-1H-1,2,3-triazol-4-yl] ethanones (IIa–IIe) readily transform into [5-methyl-1-(R-phenyl)-1H-1,2,3-triazol-4-yl] acetic acids (IVa–IVc) by the method of Wilgerodt-Kindler. The (5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)acetic acid reacts with 5-phenyl-4-amino-4H-1,2,4-triazol-3-thiol affording 6-[(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl) methyl]-3-phenyl[1,2,4] triazolo[3,4-b] [1,3,4] thiadiazole (VI). Original Russian Text ? N.T. Pokhodylo, R.D. Savka, V.S. Matiichuk, N.D. Obushak, 2009, published in Zhurnal Obshchei Khimii, 2009, vol. 79, no. 2, pp. 320–325.     

Chiral Auxiliary-Bearing Isocyanides as Synthons: Synthesis of Strongly Fluorescent (+)-5-(3,4-Dimethoxyphenyl)-4-[[N- [(4S)-2-oxo-4-(phenylmethyl)-2-oxazolidinyl]]carbonyl]oxazole and Its Enantiomer

Both (4S-(+)-3-(isocyanoacetyl)-4-(phenylmethyl)-2-oxazolidinone (R)-1 and its enantiomer (S)-1 have been synthesized as potentially useful synthons in asymmetric synthesis. Optically active (+)-5-(3,4-dimethoxyphenyl)-4-[[N-[(4S)-2-oxo-4-(phenylmethyl)-2-oxazolidinyl]]carbonyl] oxazole (S)-2 and its enantiomer (R)-2 obtained by treating 3,4-dimethoxybenzoyl chloride with (S)-1 and (R)-1, respectively, in the presence of the nonionic superbase P(MeNCH(2)CH(2))(3)N, have high fluorescence quantum yields. The molecular structure of (S)-2 obtained by X-ray means is also presented.     

Synthesis of 5-Substituted-3-[(2’R,4’R)-4’-Hydroxy-2’-hydroxymethyltetrahydrofuran-4’-yl]-1,2,4-oxadiazoles and Their Epimers

The syntheses of 5-substituted-3-[( 2' R, 4' R)-4 ' -hydroxy-2 ' -hydroxymethyltetra-hydrofuran-4' -yl]D-1 ,2, 4-oxadiazoles and their epimers were accomplished with the aid of th construction of 1,2, 4-oxadiazoles by condensation of O-acylated cyanohydrins with hydroxylamine via intramolecular transacylation and subsequent cyclization.     

Synthesis and pharmacological effects of optically active 2-[4-(4-benzhydryl-1-piperazinyl)phenyl]-ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylate hydrochloride

Optically active 2-[4-(4-benzhydryl-1-piperazinyl)phenyl]ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylate [(S)-(+)-1 and (R)-(-)-1] hydrochlorides were synthesized with high optical purities from (R)-(-)- and (S)-(+)-1,4-dihydro-5-methoxycarbonyl-2,6-dimethyl-4-(3-nitrophenyl)- 3-pyridinecarboxylic acids [(R)-(-)-6 and (S)-(+)-6], which are available from (+/-)-6 by optical resolution using quinidine and cinchonidine, respectively. From pharmacological investigations of (S)-(+)-1 and (R)-(-)-1 such as the antihypertensive effect on spontaneously hypertensive rats and inhibition of [3H]nimodipine binding to rat cardiac membrane homogenate, the active form of 1 was defined to be the (4S)-(+)-enantiomer of 1.     

Asymmetric synthesis of (4R,5R)-cytoxazone and (4R,5S)-epi-cytoxazone

(4R,5R)-Cytoxazone has been prepared in four steps and in 61% overall yield and >98% ee. Conjugate addition of lithium (R)-N-benzyl-N-[small alpha]-methylbenzylamide to tert-butyl (E)-3-(p-methoxyphenyl)prop-2-enoate and subsequent in situ diastereoselective enolate oxidation with (+)-(camphorsulfonyl)oxaziridine gave tert-butyl (2R,3R,[small alpha]R)-2-hydroxy-3-(p-methoxyphenyl)-3-(N-benzyl-N-[small alpha]-methylbenzylamino)propanoate in >98% de. Subsequent N-benzyl deprotection to the primary [small beta]-amino ester via hydrogenolysis, oxazolidinone formation with C(2)-retention by treatment with diphosgene and chemoselective ester reduction furnishes (4R,5R)-cytoxazone. The synthesis of the C(5)-epimer, (4R,5S)-epi-cytoxazone in 44% overall yield, has also been completed via a protocol involving N-Boc protection of the primary [small beta]-amino ester, utilization of the N-Boc group to facilitate simultaneous C(2)-inversion and oxazolidinone formation, and subsequent reduction.     

Diastereoselective hydroxylation of 6-substituted piperidin-2-ones. An efficient synthesis of (2S,5R)-5-hydroxylysine and related alpha-amino acids

The synthesis of (2S,5R)-5-hydroxy-6-oxo-1,2-piperidinedicarboxylates (5) and related (3S,6R)-3-hydroxy-6-alkyl-2-oxo-1-piperidinecarboxylates has been developed. The approach is based on the asymmetric hydroxylation of enolates generated from the corresponding N-protected-6-substituted piperidin-2-ones. The utility of 5a as a precursor in the synthesis of (2S,5R)-5-hydroxylysine (1), an amino acid unique to collagen and collagen-like proteins, has also been demonstrated. (2S)-6-oxo-1,2-piperidinedicarboxylates (6) required for hydroxylation studies were prepared in 38-74% yield, starting from conveniently protected aspartic acid as inexpensive chiral adduct. Hydroxylation of 6 to 5 proceeds in high yield and excellent diastereoselectivity by treatment of their Li-enolate with (+)-camphorsulfonyloxaziridine at -78 degrees C. Ring opening of di-tert-butyl (2S,5R)-6-oxo-1,2-piperidinedicarboxylate ((5R)-5a) under reductive conditions afforded the corresponding 1,2-diol (17) in 91%, which was further transformed to (2S,5R)-5-hydroxylysine in four steps (84%). 17 is also a versatile intermediate in the preparation of tert-butyl (2S,5R)-2-[(tert-butoxycarbonyl)amino]-5-hydroxy-6-iodohexanoate (3) and tert-butyl (2S)-2-[(tert-butoxycarbonyl)amino]-4-[(2R)-oxiranyl]butanoate (4), two amino acid derivatives used in the total synthesis of the bone collagen cross-link (+)-pyridinoline (2a).     

New liquid crystal compounds ( )-4-[5-(2-Methylbutyl)-1,3-dioxan-2-yl]phenyl 4-alkoxybenzoate

New liquid crystal compounds, (+)-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl] phenyl 4-alkoxybenzoates (5), were synthesized. The mesomorphic behaviour of these compounds is compared with that of (+)-4-(5-alkyl-1,3-dioxan-2-yl)-phenyl 4-(2-methylbutoxy)benzoates (6). While compounds 6 exhibited a chiral smectic C phase, the corresponding compounds 5 did not. This might mean that for the appearance of a chiral smectic C phase in these types of compounds, it is necessary that the carbonyl and the chiral groups exist at nearby positions. Transition temperatures to those isotropic state for compounds 5 were lower than those for compounds 6. This result is common in both cases of (+)-4-alkoxycarbonylphenyl-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl]benzoates (7), and (+)-4-(2-methylbutoxy-carbonyl)phenyl 4-(5-alkyl-1,3-dioxan-2-yl)-benzoates (8).     

(Fluoren-9-ylidene)methanedithiolato complexes of gold: synthesis, luminescence, and charge-transfer adducts

Piperidinium 9H-fluorene-9-carbodithioate and its 2,7-di-tert-butyl-substituted analogue [(pipH)(S(2)CCH(C(12)H(6)R(2)-2,7)), R = H (1a), t-Bu (1b)] and 2,7-bis(octyloxy)-9H-fluorene-9-carbodithioic acid [HS(2)CCH(C(12)H(6)(OC(8)H(17))(2)-2,7), 2] and its tautomer [2,7-bis(octyloxy)fluoren-9-ylidene]methanedithiol [(HS)(2)C=C(C(12)H(6)(OC(8)H(17))(2)-2,7), 3] were employed for the preparation of gold complexes with the (fluoren-9-ylidene)methanedithiolato ligand and its substituted analogues. The gold(I) compounds Q(2)[Au(2)(mu-kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)], where Q(+) = PPN(+) or Pr(4)N(+) for R = H (Q(2)4a) or Q(+) = Pr(4)N(+) for R = OC(8)H(17) [(Pr(4)N)(2)4c], were synthesized by reacting Q[AuCl(2)] with 1a or 2 (1:1) and excess piperidine or diethylamine. Complexes of the type [(Au(PR'3))(2)(mu-kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)] with R = H and R' = Me (5a), Et (5b), Ph (5c), and Cy (5d) or R = t-Bu and R' = Me (5e), Et (5f), Ph (5g), and Cy (5h) were obtained by reacting [AuCl(PR'(3))] with 1a,b (1:2) and piperidine. The reactions of 1a,b or 2 with Q[AuCl(4)] (2:1) and piperidine or diethylamine gave Q[Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)] with Q(+) = PPN(+) for R = H [(PPN)6a], Q(+) = PPN(+) or Bu(4)N(+) for R = t-Bu (Q6b), and Q(+) = Bu(4)N(+) for R = OC(8)H(17) [(Bu(4)N)6c]. Complexes Q6a-c reacted with excess triflic acid to give [Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(kappa(2)-S,S-S(2)CCH(C(12)H(6)R(2)-2,7))] [R = H (7a), t-Bu (7b), OC(8)H(17) (7c)]. By reaction of (Bu(4)N)6b with PhICl(2) (1:1) the complex Bu(4)N[AuCl(2)(kappa(2)-S,S-S(2)C=C(C(12)H(6)(t-Bu)(2)-2,7))] [(Bu(4)N)8b] was obtained. The dithioato complexes [Au(SC(S)CH(C(12)H(8)))(PCy(3))] (9) and [Au(n)(S(2)CCH(C(12)H(8)))(n)] (10) were obtained from the reactions of 1a with [AuCl(PCy(3))] or [AuCl(SMe(2))], respectively (1:1), in the absence of a base. Charge-transfer adducts of general composition Q[Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)].1.5TCNQ.xCH(2)Cl(2) [Q(+) = PPN(+), R = H, x = 0 (11a); Q(+) = PPN(+), R = t-Bu, x = 2 (11b); Q(+) = Bu(4)N(+), R = OC(8)H(17), x = 0 (11c)] were obtained from Q6a-c and TCNQ (1:2). The crystal structures of 5c.THF, 5e.(2)/(3)CH(2)Cl(2), 5g.CH(2)Cl(2), (PPN)6a.2Me(2)CO, and 11b were solved by X-ray diffraction studies. All the gold(I) complexes here described are photoluminescent at 77 K, and their emissions can be generally ascribed to LMMCT (Q(2)4a,c, 5a-h, 10) or LMCT (9) excited states.     

Theoretical study on the geometry and vibration of 1-[6-(4-Chlorophenyl)-1-[(6-chloropyridin-3-yl)methyl]-2-[(6-chloropyridin-3-yl)methylsulfanyl]-4-methyl-1,6-dihydropyrimidin-5-yl]ethanone

The solid phase FT-IR and FT-Raman spectra of 1-[6-(4-chlorophenyl)-1-[(6-chloropyridin-3-yl)methyl]-2-[(6-chloropyridin-3-yl)methylsulfanyl]-4-methyl-1,6-dihydropyrimidin-5-yl]ethanone (C25H21Cl3N4OS) were recorded in the region 4000-400 and 3500-100cm(-1), respectively. The vibrational spectra have been computed using density functional theory (B3LYP) and ab initio molecular orbital calculation (HF) with 6-31G(d, p) basis sets. A close agreement was achieved between the observed and calculated frequency by employing normal coordinate calculations. The observed and simulated spectra were found to be well comparable.     

Design, synthesis, and 1,3-dipolar cycloaddition of (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxides as chiral (E)-geometry-fixed alpha-alkoxycarbonylnitrones

Optically pure (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1, 4-oxazin-2-one N-oxides [(5R)- and (5S)-2] were designed as chiral (E)-geometry-fixed alpha-alkoxycarbonylnitrones 1. The nitrones (5R)- and (5S)-2 were synthesized by three-step oxidation of (R)- and (S)-phenylglycinols [(R)- and (S)-3], condensation of the resulting (R)- and (S)-2-hydroxylamino-2-phenylethanols [(R)- and (S)-5] with glyoxylic acid, and cyclization of the intermediary nitrones (R)- and (S)-6b. The nitrone (5R)-2reacted with olefins 7-14 under mild conditions to afford the corresponding cycloadducts 15-22 as the main products via the least sterically demanding exo modes. Cycloadduct 30 obtained from (5S)-2 and cyclopentadiene was effectively elaborated to (1S,4S, 5R)-4-benzyloxycarbonylamino-2-oxabicyclo[3.3.0]oct-7-en-3-one (28), the key synthetic intermediate of carbocyclic polyoxin C.     

Preparation of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)-5-methoxybenzo[b]furan derivatives and their leukotriene B(4) inhibitory activity

A series of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)benzo[b]furan derivatives 6-10 were prepared and their leukotriene B(4) inhibitory activity was evaluated. We found that several compounds showed strong inhibition of calcium mobilization in CHO cells overexpressing human BLT(1) and BLT(2) receptors. Among them, 3-(4-chlorophenyl)-2-[5-formyl-2-[(dimethylamino)methyleneamino]thiazol-4-yl]-5-methoxybenzo[b]furan 9b showed the most potent and selective inhibition for the human BLT(2) receptor, and its IC(50) value was smaller than that of the selected positive control compound, ZK-158252.     

Synthesis of novel 4(5)-(5-aminotetrahydropyran-2-yl)imidazole derivatives and their in vivo release of neuronal histamine measured by brain microdialysis

The (2R,5S)-trans- and (2S,5S)-cis-stereoisomers 1a and 1b of 4(5)-(5-aminotetrahydropyran-2-yl)imidazole, which have two chiral centers and adopt a stable chair conformation, were synthesized via cyclization of diol intermediates 7 using L-glutamine as the starting material. Their enantiomers, (2S,5R)-trans-1c and (2R,5R)-cis-1d, were synthesized by the same methodology from D-glutamine. Stereo isomers 1a-d were converted into cyanoguanidines 11a-d, and into N-isopropyl and N-3,3-dimethylbutyl derivatives 12a-d and 13a-d, respectively. The results of in vivo brain microdialysis of the derivatives apparently indicated that only (2S,5R)-isomers increased the release of neuronal histamine. Among the many (2S,5R)-N-alkyl derivatives, 13c (OUP-133) and 18 (OUP-153) increased histamine release to 180-190% and 180-200% of basal levels, respectively, and were found to be novel histamine H(3) antagonists.     

N-杂环甲基2-(4-杂芳氧基苯氧基)丙酰胺的合成及除草活性

以2-(4-羟基苯氧)丙酸为原料,设计合成了16个新的手性N-杂环甲基2-(4-杂芳氧基苯氧基)丙酰胺化合物,其化学结构经核磁共振、色谱-质谱、红外光谱及元素分析确证.初步生物活性测定结果表明,合成的化合物在2.25×103g/ha剂量时对单子叶杂草马唐(Digitaria sanguinalis)、稗草(Echinochloa crus-galli)及狗尾草(Setaria viridis)等均具有90%以上的活性;进一步活性及作物安全性测试表明,化合物(R)-(+)-N-[(6-氯吡啶-3-基)甲基]-2-[4-(3-氯-5-三氟甲基吡啶-2-基氧基)苯氧基]丙酰胺(2b)的除草活性高于噁唑酰草胺,且对水稻茎叶处理安全,同时对水稻田主要杂草千金子的活性远高于氰氟草酯;化合物的除草活性与立体构型有关,R构型为活性构型.     

An ionic 2D inorganic–organic hybrid of tris[((1H-tetrazol-5-yl)methyl) morpholine] dodecatungstophosphate(V) pentahydrate: Synthesis X-ray crystal structure, and spectroscopic characterizations

A unique ionic hybrid material [C6H12N5O]3[(PO4)W12O36]•5H2O has been synthesized from the reaction of ((1H-tetrazole-5-yl)methyl)morpholine and α-H3[(PO4)W12O36].21H2O. It has successfully been characterized by elemental analysis, IR and 1H NMR spectroscopies, TGA and single-crystal X-ray diffraction method. The title compound is constructed from the three [C6H12N5O]+ cations and α-Keggin [(PO4)W12O36]3- polyoxoanion. The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like (2D/∞[(PO4)W12O36]3-) which forming via van der Waals interactions along the x axis.     

Gold(I) complexes of water-soluble diphos-type ligands: synthesis, anticancer activity, apoptosis and thioredoxin reductase inhibition

Gold(I) complexes of imidazole and thiazole-based diphos type ligands were prepared and their potential as chemotherapeutics investigated. Depending on the ligands employed and the reaction conditions complexes [L(AuCl)(2)] and [L(2)Au]X (X = Cl, PF(6)) are obtained. The ligands used are diphosphanes with azoyl substituents R(2)P(CH(2))(2)PR(2) {R = 1-methylimidazol-2-yl (1), 1-methylbenzimidazol-2-yl (4), thiazol-2-yl (5) and benzthiazol-2-yl (6)} as well as the novel ligands RPhP(CH(2))(2)PRPh {R = 1-methylimidazol-2-yl (3)} and R(2)P(CH(2))(3)PR(2) {R = 1-methylimidazol-2-yl (2)}. The cytotoxic activity of the complexes was assessed against three human cancer cell lines and a rat hepatoma cell line and correlated to the lipophilicity of the compounds. The tetrahedral gold complexes [(3)(2)Au]PF(6) and [(5)(2)Au]PF(6) with intermediate lipophilicity (logD(7.4) = 0.21 and 0.25) showed significant cytotoxic activity in different cell lines. Both compounds induce apoptosis and inhibit the enzymes thioredoxin reductase and glutathione reductase.     

Crystal structure of 6-[(1-methyl-4-nitroimidazol-5-yl)thio] purine

6-[(l-methyl-4-nitroimidazol-5-yl)thio] purine, is an immunosuppressant derivative of the antitumour drug, 6-mercaptopurine. Crystals are monoclinic witha = 4.488(2),b = 31.886(4), c = 8.067(2)A and β= 105.99(2)° in the space group P2₁/c. The crystal structure was solved by direct methods using diffractometer data and refined by least squares to anR- index of 0.065 for 502 observed reflections. The molecule crystallizes in the N(9)-H tautomer form, in contrast to the N(7)-H tautomer form found in crystals of 6-mercaptopurine and assume a conformation in which the substituents on the sulphur atom are directed away from imidazole moiety of the purine NCL Communication number 3313