A straightforward and flexible [4 + 2] route to beta-C-naphthyl-2-deoxy-glycosides through tandem hydroboration-ketal reduction: de novo access to C-naphthyl-6-fluoro and 6,6-difluoro 2-deoxyglycosides

[reaction: see text] Under standard hydroboration-oxidation conditions, the dihydropyrans 4 underwent a highly stereocontrolled tandem reaction, involving the expected hydration of the double bond together with the reduction of the ketal moiety. This unprecedented transformation gives rise to a short, [4 + 2]-based synthetic route to (+/-)-beta-C-naphthyl-2-deoxyglycosides 5, which allows a significant structural and functional diversity at C-6. We thus described the first synthesis of (+/-)-C-aryl-6-fluoro and -6,6-difluoro olivosides, via the allylic mono- and difluorides produced by regioselective fluorination of, respectively, hydroxyalkyl and oxoalkyl dihydropyran derivatives.     

Functional polymers. XVI. Synthesis and polymerization of 2(2-hydroxy-5-isopropenylphenyl)-2H-benzotriazole and a new synthesis of 2(2-hydroxy-5-vinylphenyl)2H-benzotriazole

2(2-Hydroxy-5-isopropenylphenyl)2H-benzotriazole was synthesized in 40% overall yield starting from o-nitroaniline. Diazotization in aqueous hydrochloric acid gave o-nitrophenyl diazonium chloride which was condensed with p-hydroxyacetophenone; the azo compound was reduced to 2(2-hydroxy-5-acetylphenyl) 2H-benzotriazole with zinc powder in sodium hydroxide solution and the 2-hydroxy group of the compound was acetylated. Treatment of the acetyl compound with methyl Grignard reagent resulted in the methylation of the 5-acetyl group to 2[2-acetoxy-5(2-hydroxy-2-propyl)phenyl]2H-benzotriazole which was then dehydrated with potassium hydrogen sulfate to the desired 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole. This monomer did not homopolymerize, but was copolymerized readily with styrene, methyl methacrylate, and n-butyl acrylate with azobisisobutyronitrile as the initiator. 2(2-Acetoxy-5-acetylphenyl)2H-benzotriazole was also reduced with sodium borohydride to form 2[2-acetoxy-5-(1-hydroxyethyl)phenyl]2H-benzotriazole which was dehydrated and hydrolyzed to the known 2(2-hydroxy-5-vinylphenyl)-2H-benzotriazole. This route provides a novel and simpler synthesis of 2(2-hydroxy-5-vinylphenyl)2H-benzotriazole.     

Role of the transition metal in metallaborane chemistry. Reactivity of (Cp*ReH2)2B4H4 with BH3.thf, CO, and Co2(CO)8

The reaction of Cp*ReCl4, [Cp*ReCl3]2, or [Cp*ReCl2]2 (Cp* = eta 5-C5Me5) with LiBH4 leads to the formation of 7-skeletal-electron-pair (7-sep) (Cp*ReH2)2(B2H3)2 (1) together with Cp*ReH6. Compound 1 is metastable and eliminates H2 at room temperature to generate 6-sep (Cp*ReH2)2B4H4 (2). The reaction of 2 with BH3.thf produces 7-sep (Cp*Re)2B7H7, a hypoelectronic cluster characterized previously. Heating of 2 with 1 atm of CO leads to 6-sep (Cp*ReCO)(Cp*ReH2)B4H4 (3). Both 2 and 3 have the same bicapped Re2B2 tetrahedral cluster core structure. Monitoring the reaction of 2 with CO at room temperature by NMR reveals the formation of a 7-sep, metastable intermediate, (Cp*ReCO)(Cp*ReH2)(B2H3)2 (4), which converts to 3 on heating. An X-ray structure determination reveals two isomeric forms (4-cis and 4-trans) in the crystallographic asymmetric unit which differ in geometry relative to the disposition of the metal ancillary ligands with respect to the Re-Re bond. The presence of these isomers in solution is corroborated by the solution NMR data and the infrared spectrum. In both isomers, the metallaborane core consists of fused B2Re2 tetrahedra sharing the Re2 fragment. On the basis of similarities in electron count and spectroscopic data, 1 also possesses the same bitetrahedral structure. The reaction of 2 with CO2(CO)8 results in the formal replacement of the four rhenium hydrides with a 4-electron CO2(CO)5 fragment, thereby closing the open face in 2 to produce the 6-sep hypoelectronic cluster (Cp*Re)2CO2(CO)5B4H4 (5). These reaction outcomes are compared and contrasted with those previously observed for 5-sep (Cp*Cr2)2B4H8.     

Predicting the energy of the water exchange reaction and free energy of solvation for the uranyl ion in aqueous solution

The structures and vibrational frequencies of UO2(H2O)4(2+) and UO2(H2O)5(2+) have been calculated using density functional theory and are in reasonable agreement with experiment. The energies of various reactions were calculated at the density functional theory (DFT) and MP2 levels; the latter provides the best results. Self-consistent reaction field calculations in the PCM and SCIPCM approximations predicted the free energy of the water exchange reaction, UO2(H2O)4(2+) + H2O <--> UO2(H2O)5(2+). The calculated free energies of reaction are very sensitive to the choice of radii (O and H) and isodensity values in the PCM and SCIPCM models, respectively. Results consistent with the experimental HEXS value of -1.19 +/- 0.42 kcal/mol (within 1-3 kcal/mol) are obtained with small cavities. The structures and vibrational frequencies of the clusters with second solvation shell waters: UO2(H2O)4(H2O)8(2+), UO2(H2O)4(H2O)10(2+), UO2(H2O)4(H2O)11(2+), UO2(H2O)5(H2O)7(2+), and UO2(H2O)5(H2O)10(2+), were calculated and are in better agreement with experiment as compared to reactions involving only UO2(H2O)4(2+) and UO2(H2O)5(2+). The MP2 reaction energies for water exchange gave gas-phase results that agreed with experiment in the range -5.5 to +3.3 kcal/mol. The results were improved by inclusion of a standard PCM model with differences of -1.2 to +2.7 kcal/mol. Rearrangement reactions based on an intramolecular isomerization leading to a redistribution of water in the two shells provide good values in comparison to experiment with values of Delta G(exchange) from -2.2 to -0.5 kcal/mol so the inclusion of a second hydration sphere accounts for most solvation effects. Calculation of the free energy of solvation of the uranyl cation yielded an upper bound to the solvation energy of -410 +/- 5 kcal/mol, consistent with the best experimental value of -421 +/- 15 kcal/mol.     

Migratory insertion of the R2P group into a nitrogen-nitrogen bond - a novel type of rearrangement in phosphorus-nitrogen ligand chemistry. 3. The rearrangement of triphosphinohydrazide ligand -N(PPh2)-N(PPh2)2 to triphosphazenide anion {[(Ph2P-N]2PPh2}- in the coordination sphere of divalent cobalt and nickel

Hydrazine dihydrochloride reacts with 3 equiv of Ph2PCl in tetrahydrofuran in the presence of triethylamine to give tris(diphenylphosphino)hydrazine (1) in 70% yield. Each nitrogen atom in 1 has a trigonal-planar environment according to X-ray analysis. Thermolysis of 1 at 130 degrees C results in the formation of two products: bis(diphenylphosphino)amine and octaphenylcyclotetraphosphazene. The interaction of free ligand 1 with NiBr2 affords a simple adduct [(Ph2P)2N-NH-PPh2]NiBr2, while its anionic (hydrazide) form undergoes rearrangement in a coordination sphere of divalent cobalt and nickel involving migratory insertion of the Ph2P group into a nitrogen-nitrogen bond. The reaction of 1 with cobalt bis(trimethylsilyl)amide, [(Me3Si)2N]2Co, yields the complex of phosphazenide-type (Me3Si)2N-Co[(Ph2PN)2PPh2] (2) in 86% yield. A similar reaction of 1 with nikelocene proceeds with substitution of one Cp ring to form durable 18-electron complex CpNi[(Ph2PN)2PPh2] (3).     

Reactions of 7-Chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2,2-dioxide in Various pH Solutions

Diazepam ( 1 ) is a frequently prescribed hypnotic/anxiolytic drug worldwide. 7-Chloro-1,3-dihydro-l-methyl-5-phenyl-2H-1,4-benzodiazepin-2,2-dioxide ( 2 ) is an initial alkaline hydrolysis product of 1. The mechanisms in the conversion of 2 to 2-methylamino-5-chloro-α-(phenylbenzylidene)glycinate ( 3 ), 2-methylamino-5-chlorobenzophenone ( 4 ), and 1 in aqueous solutions with pH ranging from 0 to 12.2 is the subject of this report. Results of temperature-dependent hydrolysis kinetics and product identification indicated that: (1) in solutions with pH between 7 and 12.2, 2 underwent a ring-opening reaction to form 3; the rate decreased with increasing pH. (2) In solutions with pH between 2 and 7, 2 was rapidly converted to 3, followed by a pH-dependent conversion to 4 ; the rate increased with decreasing pH and became less sentitive to pH at pH ≤ 4.5. (3) In solutions with pH between 0 and 2, 2 was rapidly converted to 4 and 1; the percentage of 1 increased with decreasing pH. (4) A 2 containing one oxygen-18 atom lost 50% of its oxygen-18 following conversion to 1 in 1 M HCl. In addition to understanding the mechanism in the transformations of 2 in various pH solutions, this study established a simple and efficient method in the quantitative conversion of 1 to 4 and in the preparation of an oxygen-18-containing 1 at C2 position.     

Chemistry of ruthenium(II) monohydride and dihydride complexes containing pyridyl donor ligands including catalytic ketone H2-hydrogenation

In this study we determine the changes to the properties of dihydride catalysts for ketone H2-hydrogenation by successively replacing the amine donors in the known dach complex RuH2(PPh3)2(dach) (2a), dach = 1,2-(R,R)-diaminocyclohexane, with one pyridyl group in the corresponding 2-(aminomethyl)pyridine (ampy) complexes RuH2(PPh3)2(ampy) (2b) and with two pyridyl groups in the complexes RuH2(PPh3)2(bipy) (2c) and RuH2(PPh3)2(phen) (2d). The ruthenium monohydride complex, (OC-6-54)-RuHCl(PPh3)2(ampy), (1b with Cl trans to H) was prepared by the addition of 1 equiv of ampy to RuHCl(PPh3)3 in THF. Treatment of the monohydride complex with K[BH(sec-Bu)3] in THF or KOtBu/H2 in toluene resulted in the formation of a mixture of at least two isomers of the highly reactive, air-sensitive ruthenium dihydride complex 2b. One is the cis dihydride (OC-6-14)-2b or more simply c,t-2b with trans PPh3 groups and another is the cis dihydride c,c-2b (OC-6-42) that has PPh3 trans to H and PPh3 trans to N(pyridyl). The isomer c,c-2b slowly converts to c,t-2b in solution. The reaction of 1b with KOtBu under Ar results in the formation of a mixture that includes a complex with an imino ligand HN=CH-2-py while the same reaction under H2 leads to c,c-2b and then c,t-2b. The dach complex c,t-2a, reacts with ampy, 2,2'-bipyridine (bipy), and 1,10-phenanthroline (phen) in refluxing THF to form the substituted cis-dihydride complexes c,t-2b, (OC-6-13)-RuH2(PPh3)2(bipy) (c,t-2c with trans PPh3 groups) and (OC-6-13)-RuH2(PPh3)2(phen), c,t-2d, respectively. The dihydrides containing amino groups and cis-PPh3 groups, i.e., c,c-2a or c,c-2b, are active precatalysts for the H2-hydrogenation of acetophenone (neat or in benzene) under mild reaction conditions, whereas those with trans-PPh3 groups, c,t-2a and c,t-2b are much less active. The combination of ampy complex 1b and KOtBu also provides a catalyst in benzene that is more active than the corresponding dach system. The complexes without amino groups c,t-2c and c,t-2d are air-stable and inactive as hydrogenation catalysts under comparable conditions. The mechanism of hydrogenation of ketones catalyzed by isomers of 2a,b is thought to be similar and to proceed via a trans-dihydride complex, t,c-2a or t,c-2b, and an amido complex, neither of which are directly observed for the ampy complexes. The dihydride complex c,t-2b reacts with formic acid to give (OC-6-45)-RuH(OCHO)(PPh3)2(ampy), 3b, with formate trans to hydride. The structures of 1b, c,t-2b, c,t-2c, and 3b have been determined by single-crystal X-ray diffraction.     

Effect of matrix on IR frequencies of acetylene and acetylene-methanol complex: infrared matrix isolation and ab initio study

Effect of nitrogen and argon matrices on the C-H asymmetric stretching and bending infrared frequencies of the acetylene molecule, C(2)H(2), has been studied by matrix isolation experiments as well as by calculations at MP2 level of theory. The complexes of C(2)H(2) in nitrogen and argon matrices, viz., C(2)H(2)(N(2))(m) (with m=2-8) and C(2)H(2)(Ar)(n) (with n=2-10) are theoretically explored. The computed acetylenic C-H asymmetric stretch in C(2)H(2)-nitrogen complexes shows a redshift of 3.0 to 11.9 cm(-1) compared with the frequencies of the free acetylene molecule, and a corresponding blueshift of 7.4 to 26.2 cm(-1) when C(2)H(2) is complexed with argon atoms. The trends in the computed shifts are in good agreement with the experiments. The molecular electrostatic potential minimum of C(2)H(2) becomes more negative when complexed with nitrogen than on complexation with argon. This observation implies a greater basic character for C(2)H(2) in the nitrogen matrix, favoring the formation of H-pi(C(2)H(2)-MeOH) complex as compared to that in the Ar matrix. Experimentally the preferential formation of H-pi(C(2)H(2)-MeOH) complex in the N(2) matrix has indeed been observed.     

Mercury(II) 2-aminoethanethiolate clusters: intramolecular transformations and mechanisms

The combination of HgF2 and 2-aminoethanethiol (AET, with some AET.HCl present) yielded a cyclic tetranuclear thiolate, [Hg4Cl4(SCH2CH2NH2)4] (1), with alternating Hg and S atoms. The Cl from the reaction mixture led to the formation of Hg-Cl bonds with no Hg-F in the final product. In contrast, a similar reaction with HgBr2 yielded a nonanuclear cluster, [Hg9Br15(SCH2CH2NH3)15]3+ (2), and the disulfide salt {[HgBr4][(NH3CH2CH2S-)2]} (3). Despite similar reactions, the AET groups in 2 are protonated compared to the nonprotonated amine groups in 1, which allows the ligand to chelate the Hg atom in the latter compound. The reaction with HgI2 yielded a cyclic tetranuclear compound, [Hg4I6(SCH2CH2NH2)2(SCH2CH2NH3)2](H2O/EtOH) (4), containing protonated and nonprotonated AET groups. Compound 4 at room temperature irreversibly rearranges to [Hg4I4(SCH2CH2NH2)4] (5), which is isostructural to 1. A systematic pathway for the formation of 1 along with the intramolecular conversion of 4 to 5 is proposed. These compounds demonstrate that very diverse Hg-S compounds form under similar reaction conditions.     

Formation and characterization of mononuclear and dinuclear manganese oxide-dioxygen complexes in solid argon

A manganese atom reacts with dioxygen to form the previously characterized MnO 2 molecule in solid argon under UV-visible light irradiation. Subsequent sample annealing allows the dioxygen molecules to diffuse and to react with MnO 2 to give the (eta (2)-O 2)MnO 2 complex, which is characterized to be a side-on bonded peroxo manganese dioxide complex. The manganese tetraoxide MnO 4, which was predicted to be less stable than the (eta (2)-O 2)MnO 2 isomer, was not observed. However, the (eta (2)-O 2)MnO 2 complex reacts with another weakly coordinated dioxygen to give the (eta (2)-O 2)MnO 4 complex via visible light irradiation, in which the manganese tetraoxide is coordinated and stabilized by a side-on bonded O 2 molecule. Manganese dimer reacts with dioxygen to form the cyclic Mn(mu-O) 2Mn cluster spontaneously upon annealing, which further reacts with dioxygen to give the (eta (2)-O 2) 2Mn(mu-O) 2Mn cluster, a side-on bonded disuperoxide complex with a planar D 2 h structure.     

Syntheses and structures of alkaline earth metal bis(diphenylamides)

Various preparative procedures are employed in order to synthesize alkaline earth metal bis(diphenylamides) such as (i) metalation of HNPh2 with the alkaline earth metal M, (ii) metalation of HNPh2 with MPh2, (iii) metathesis reaction of MI2 with KNPh2, (iv) metalation of HNPh2 with PhMI in THF, and (v) metathesis reaction of PhMI with KNPh2 followed by a dismutation reaction yielding MPh2 and M(NPh2)2. The magnesium compounds [(diox)MgPh2]infinity (1) and (thf)2Mg(NPh2)2 (2) show tetracoordinate metal atoms, whereas in (dme)2Ca(NPh2)2 (3), (thf)4Sr(NPh2)2 (4), and (thf)4Ba(NPh2)2 (5) the metals are 6-fold coordinated. Additional agostic interactions between an ipso-carbon of one of the phenyl groups of the amide ligand and the alkaline earth metal atom lead to unsymmetric coordination of the NPh2 anions with two strongly different M-N-C angles in 3-5.     

Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: water-catalyzed O--H-insertion and HI-elimination reactions of isodiiodomethane (CH2I-I) with water

A combined experimental and theoretical study of the ultraviolet photolysis of CH2I2 in water is reported. Ultraviolet photolysis of low concentrations of CH2I2 in water was experimentally observed to lead to almost complete conversion into CH2(OH)2 and 2HI products. Picosecond time-resolved resonance Raman spectroscopy experiments in mixed water/acetonitrile solvents (25%-75% water) showed that appreciable amounts of isodiiodomethane (CH2I-I) were formed within several picoseconds and the decay of the CH2I-I species became substantially shorter with increasing water concentration, suggesting that CH2I-I may be reacting with water. Ab initio calculations demonstrate the CH2I-I species is able to react readily with water via a water-catalyzed O--H-insertion and HI-elimination reaction followed by its CH2I(OH) product undergoing a further water-catalyzed HI-elimination reaction to make a H2C=O product. These HI-elimination reactions produce the two HI leaving groups observed experimentally and the H2C=O product further reacts with water to produce the other final CH2(OH)2 product observed in the photochemistry experiments. These results suggest that CH2I-I is the species that reacts with water to produce the CH2(OH)2 and 2HI products seen in the photochemistry experiments. The present study demonstrates that ultraviolet photolysis of CH2I2 at low concentration leads to efficient dehalogenation and release of multiple strong acid (HI) leaving groups. Some possible ramifications for the decomposition of polyhalomethanes and halomethanols in aqueous environments as well as the photochemistry of polyhalomethanes in the natural environment are briefly discussed.     

Glucagon-like peptide 2 (GLP-2), an intestinotrophic mediator

Glucagon-like peptide 2 (GLP-2) is a newly discovered gastrointestinal peptide with 33% sequence homology to glucagon. GLP-2 has attracted interest because of its potent intestinotrophic endocrine/paracrine actions. The peptide, consisting of 33-amino-acid, results from expression of the glucagon gene in the enteroendocrine L-cells of the intestinal mucosa, from where it is released mainly in response to luminal contact with unabsorbed nutrients. In addition to mucosal growth, GLP-2 enhances activities of several intestinal brush-border enzymes, and it delays gastric transit, thereby increasing the intestinal capacity for nutrient absorption. Thus, it appears that GLP-2 serves to ensure an optimal intestinal capacity. The physiological responses following exogenous administration of GLP-2 have been intensely investigated, and these appear to be rather specific for the gut, which is concordant with the localization of the GLP-2 receptor. In addition, treatment with GLP-2 in experimental animal models of several enteropathies indicates that GLP-2 ameliorates most of the observed intestinal abnormalities in these conditions. Following secretion to the blood stream, the intact peptide is degraded rather rapidly by an aminopeptidase. To circumvent the rapid and widespread metabolization of intact GLP-2, degradation-resistant synthetic GLP-2 analogues have been developed together with other approaches, such as inhibition of the GLP-2 degrading enzyme. This is of particular interest with respect to developing GLP-2 into a useful therapeutic agent in conditions with compromised intestinal function, since the first clinical trial has already indicated the potential of GLP-2 treatment in patients with short bowel syndrome.     

RADIATION DEGRADATION OF CHITOSAN IN THE PRESENCE OF H2O2

INTRODUCTIONChitosan, poly-β-(1 -?4)-D-glucosamine, can be obtained from chitin by deacetylation with alkali. It is soluble indilute acidic medium due to the presence of amino groups. The use of chitosan in many areas, such as foodprocessing, biochemistry, Pharmaceuticals, medicine, and agriculture has been developed over the pastdecades[1,2].In recent years, it has been reported that many properties of chitosan depend on the molecular weight[3]. Thechitosan oligomers possess better fun…     

Environmentally benign processes for making useful fluorocarbons: nickel- or copper(I) iodide-catalyzed reaction of highly fluorinated epoxides with halogens in the absence of solvent and thermal addition of CF2I2 to olefins

Highly fluorinated epoxides react with halogens in the presence of nickel powder or CuI at elevated temperatures to provide a useful and general synthesis of dihalodifluoromethanes (CF(2)X(2)) and fluoroacyl fluorides (R(F)COF) in the absence of solvent. At 185 degrees C, hexafluoropropylene oxide and halogens produce CF(2)X(2) (X = I, Br) in 68-90% isolated yields, along with small amounts of X(CF(2))(n)()X, (n = 2, 3). With interhalogens I-X (X = Cl, Br), a mixture of CF(2)I(2), CF(2)XI, and CF(2)X(2) was obtained. The fluorinated epoxides substituted with perfluorophenyl, fluorosulfonyl, and chlorofluoroalkyl groups also react cleanly with iodine to give CF(2)I(2) and the corresponding fluorinated acyl fluorides in good yields. The reaction probably involves an oxidative addition of fluorinated epoxides into metal surfaces to form an oxametallacycle, followed by rapid decomposition to difluorocarbene-metal surfaces, which alters the reactivity of the difluorocarbene carbon from electrophilic to nucleophilic. The increase of nucleophilicity of difluorocarbene facilitates the reaction with electrophilic halogens. CF(2)I(2) reacted with olefins thermally to give 1,3-diiodofluoropropane derivatives. Both fluorinated and nonfluorinated alkenes gave good yields of the adducts. Reaction with ethylene, propylene, perfluoroalkylethylene, vinylidene fluoride, and trifluoroethylene provided the corresponding adducts in 58-86% yields. With tetrafluoroethylene, a 1:1 adduct was predominantly formed along with small amounts of higher homologues. In contrast to perfluoroalkyl iodides, CF(2)I(2) also readily adds to perfluorovinyl ethers to give 1,3-diiodoperfluoro ethers.     

TeSe3]2- and [TeSe2]2- as synthons

The [Au2(TeSe2)2]2- anion has been prepared from the reaction of [TeSe3]2- with AuCN in DMF in the presence of PEt3 and from the reaction of [TeSe2]2- with AuCN in DMF. Reaction of [TeSe2]2- with AuCN in DMF in the presence of PEt3 leads ultimately to the [Au2(Te2)2]2- anion.     

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde: Thioacetalization,chloromethylation, and oxidation

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde reacted with propane-1-thiol and propane-1,3-dithiol in the presence of chloro(trimethyl)silane to give previously unknown 5-[bis(propylsulfanyl)methyl]-2-(2-thienylsulfanyl)thiophene and 2-[5-(2-thienylsulfanyl)thiophen-2-yl]-1,3-dithiane. Chloromethylation of 5-(2-thienylsulfanyl)thiophene-2-carbaldehyde with formaldehyde in a stream of hydrogen chloride in the presence of zinc chloride resulted in the formation of an oligomeric product consisting of thiophene rings connected alternately by sulfur and methylene bridges. The oligomer is formed via fast polycondensation of the primary chloromethylation product with the initial aldehyde. 5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde was oxidized at the sulfide and aldehyde groups with 30% hydrogen peroxide in glacial acetic to produce 5-(2-thienylsulfonyl)thiophene-2-carboxylic acid.     

Concise syntheses of 2-aminoindans via indan-2-ol

2-Amino-5,6-dimethoxyindan hydrochloride was synthesized in seven steps and with an overall yield of 48%. Indan-2-ol was converted to 5,6-dibromo-indan-2-ol in three steps by acetylation, electrophilic bromination and deacetylation. Dimethoxylation of 5,6-dibromoindan-2-ol with NaOCH₃ in the presence of CuI gave 5,6-dimethoxy-indan-2-ol, which was converted to 2-amino-5,6-dimethoxyindan hydrochloride by azidation, followed by Pd-C catalyzed hydrogenation. Similarly, 2-amino-5-bromoindan was synthesized in five steps and with an overall yield of 50%. Indan-2-ol was converted to 2-aminoindan by azidation followed by Pd-C catalyzed hydrogenation. The reaction of 2-aminoindan with 2.5 equiv Br₂ afforded 2-amino-5,6-dibromoindan.     

Enantioselective functionalisation of the C-2' position of 1,2,3,4,5-pentamethylazaferrocene via sparteine mediated lithiation: potential new ligands for asymmetric catalysis

The s-BuLi-sparteine base combination deprotonated the C-2' position of 1,2,3,4,5-pentamethylazaferrocene and subsequent reaction with a range of electrophiles gave C-2 substituted products in 76-93% yield and approximately 80% ee. The products could be recrystallised to enrich ee's to >90%. Resubjection of the initial addition products ( approximately 80% ee) to the deprotonation conditions led to a kinetic resolution to give products with >90% ee and superior overall yields compared to recrystallisation for the cases where the electrophiles were Ph2CO, MeI and Ph2S2. Transmetallation of the 2-lithiopentamethylazaferrocene ( approximately 80% ee) with ZnCl2 allowed palladium catalysed cross coupling with a variety of C-2 haloaryl, heteroaryl and vinyl groups to give some novel C-2' substituted pentamethylazaferrocene derivatives in 61-77% yield in 80% ee. Potential N,N-chelate ligands were recrystallised to >95% ee. A novel C2-symmetric bis-pentamethylazaferrocene could be synthesised by an iron catalysed oxidative coupling of the enatioenriched C-2 lithio derivative and in the presence of a PhMe-Et2O solvent mixture proceeded in 97% ee.     

Infrared spectra and structures of the coinage metal dihydroxide molecules

Laser-ablated Cu, Ag, and Au atoms react with H2O2 and with H2 + O2 molecules during condensation in excess argon to give four new IR absorptions in each system (O-H stretch, M-O-H bend, O-M-O stretch, and M-O-H deformation modes) that are due to the coinage metal M(OH)2 dihydroxide molecules. Isotopic substitution (D2O2, 18O2, 16O18O, D2, and HD) and comparison with frequencies computed by DFT verify these assignments. The calculations converge to 2B(g) ground electronic state structures with C2h symmetry, 111-117 degrees M-O-H bond angles, and substantial covalent character for these new metal dihydroxide molecules, particularly for Au(OH)2. This is probably due to the high electron affinity of gold owing to the effect of relativity.