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Using a purification method introduced earlier based on redox properties, it is possible to isolate Sc3N@Ih-C80 and Sc3N@D3h-C78 and a mixture of Sc3N@D5h-C80 and Sc3N@D3-C68.

The presented stereoselective [3+2] cycloaddition affords the title spiro compounds in excellent yields and good diastereoselectivities.

A regiospecific bis-adduct of C70 with anthracene was prepared with unusually high yield (68%) by the Diels–Alder reaction in the absence of solvent (melt). The structure of the bis-adduct was an unexpected 12 o'clock isomer, as determined by single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and spectroscopy.

Strategies for the formation of carbon–carbon bonds from the α-thioaryl carbonyl products of substituted lactams are described. Although direct functionalization is possible, a two step process of oxidation and magnesium-sulfoxide exchange has proven optimal. The oxidation step results in the formation of two diastereomers that exhibit markedly different levels of stability toward elimination, which is rationalized on the basis of quantum mechanical calculations and X-ray crystallography. Treatment of the sulfoxide with i-PrMgCl results in the formation of a magnesium enolate that will undergo an intramolecular Michael addition reaction to form two new stereogenic centers. The relationship between the substitution patterns of the sulfoxide substrate and the efficiency of the magnesium exchange reaction are also described.

2,4,6-Triaryl-3-aroyl-4-hydroxyl-1,1-cyclohexanedicarbonitriles have been prepared by the base-catalyzed reaction of variously substituted α,β-unsaturated ketones with malononitrile in anhydrous ether at room temperature. Their structures have been established on the basis of their elemental analyses, IR, 1 H- and 13 C-NMR spectral data and X-ray crystallography

(1R*,3R*,7S*,9S*)-1,4,4-Trimethyl-9-(tert-butyldimethylsilyloxy)-e xo-11-oxatricyclo[5.3.1.0(2,6)]-undecan-3-ol, C19H36O3Si, Mr = 340.90, orthorhombic, Pbca, a = 10.411 (3), b = 13.275 (3), c = 29.085 (10) A, V = 4019 (2) A3, Z = 8, Dx (130 K) = 1.13 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 1.24 cm-1, F(000) = 1504, T = 130 K, R = 0.077 for 1005 observed reflections with I greater than 3 sigma(I). The compound, whose connectivity was not readily apparent from spectroscopic and chemical information alone, possesses a tricyclic framework containing an O-bridged bicyclo[3.2.1]octane fused in a cis-exo manner to a cyclopentanol ring. Most noteworthy is the considerably lower polarity of this compound relative to its opposite cyclopentanol stereoisomer. The close proximity [2.78 (1) A] of the bridging O atom in the [3.2.1] system to the hydroxyl O atom on the five-membered ring is suggestive of an intramolecular hydrogen bond, although the H atom could not be located.

An investigation of relative asymmetric induction and double diastereoselectivity in the intramolecular nitrile oxide-olefin cycloaddition (INOC) reaction is presented.

The 1,2-dihalogenodiborane(4) compound Br(Me2N)BB(NMe2)Br 1 reacts with Li(mes)(mes = C6H2Me3-2,4,6) or LiPh to form the derivatives Br(Me2N)BB(NMe2)(mes)2, (mes)(Me2N)BB(NMe2)(mes)3, and the previously reported (synthesised by a different route) species Ph(Me2N)BB(NMe2)Ph 4 in moderate yields. Compounds 2–4 are thermally stable, colourless, crystalline solids. All compounds were characterized by X-ray crystallography and NMR spectroscopy. Their structures have B–B bond lengths that vary from 1.682(16)A in 1 to 1.717(15)A in 3. In addition, all compounds display high angles (from 58.9 to 88.7 °) between the planes at the boron atoms and short B–N distances that are near 1.39 A. The structures of 1–4 represent, apparently, the first such acyclic examples for diborane(4) derivatives of the type B2X2(NR2)2 where X = halogen or aryl group. Crystal data: 130 K: 1, Br(Me2N)BB(NMe2)Br, monoclinic, space group P21, a= 6.789(2), b= 7.720(2), c= 10.012(4), β= 103.06(3)°, Z= 2, R= 0.048 for 1109 [I > 2.0σ(I)] data; 2, Br(Me2N)BB(NMe2)(mes), monoclinic, space group C2/c, a= 24.890(14), b= 7.662(4), c= 18.500(12), β= 116.36(4)°, Z= 8, R= 0.063 for 1910 [I > 2.0σ(I)] data; 3(mes)(Me2N)BB(NMe2)(mes), orthorhombic, space group Pbcn, a= 37.983(14), b= 14.167(5), c= 12.282(4)A, Z= 12, R= 0.095 for 1829 [I > 3.0σ(I)] data; 4, Ph(Me2N)BB(NMe2)Ph, orthorhombic, space group P212121, a= 8.579(2), b= 12.920(4), c= 13.925(3)A, Z= 4, R= 0.045 for 1776 [I > 4.0σ(I)] data.

Reaction of LiCH{sub 2}P(C{sub 6}H{sub 5}) with Cp{sub 2}NbCl{sub 2} gives paramagnetic Cp{sub 2}Nb[CH{sub 2}P(C{sub 6}H{sub 5}){sub 2}]{sub 2} (1). Oxidation of 1 gives Cp{sub 2}Nb-[CH{sub 2}P(C{sub 6}H{sub 4}){sub 2}]{sub 2}{sup +}BF{sub 4}{sup {minus}}(6); reduction gives Na{sup +}[Cp{sub 2}Nb[CH{sub 2}P(C{sub 6}H{sub 4}){sub 2}]{sub 2}]{sup {minus}} (5). Na{sup +}[Cp{sub 2}Nb[CH{sub 2}P(C{sub 6}H{sub 4}){sub 2}]{sub 2}]{sup {minus}} crystallizes as a Na(18-crown-6)(THF){sub 2}{sup +} salt in the monoclinic space group C2/c with cell parameters a = 27.088 (15) {Angstrom}, b = 9.560 (5) {Angstrom}, c = 25.903 (14), {beta} = 136.19 (3){degree}, and Z = 4. 1 reacts with (C{sub 7}H{sub 8})Mo(CO){sub 4} to give Cp{sub 2}Nb[{mu}-CH{sub 2}P(C{sub 6}H{sub 5}){sub 2}]{sub 2}Mo(CO){sub 4}(7), which crystallizes in the monoclinic space group P2{sub 1/n} with cell parameters a = 13.401 (5) {Angstrom}, b = 17.188 (5) {Angstrom}, c = 19.768 (6), {beta} = 99.25 (3){degree}, and Z = 4. 2 figs., 4 tabs.

The hexacarbonyldicobalt complexes of several appropriately designed acetylenic lactone precursors have been prepared, and lactones containing Co2(CO)6-complexed triple bonds in seven-, ten-, and eleven-membered rings obtained. The latter were best obtained through a retro-Dieckmann fragmentation of 2-(hydroxybutynyl) derivatives of 1,3-clohexanedione. Attempts to extend this reaction to cyclohexanones bearing other anion-stabilizing groups in the 2-position or to 1,3-cyclopentanediones were unsuccessful. Decomplexation afforded the metal-free 11-ring lactone, characterized crystallographically. Treatment of this system with basic reagents led to dimerization. In the case of the smaller rings, cyclization of the complexed acetylenic hydroxyacids under Mukaiyama conditions (2-chloro-N-methylpyridinium iodide, CH2Cl2, reflux) succeeded in modest yields.

We report herein full experimental details of the synthesis, structure, and reactivity of (R)- and (S)-2-tert-butyl-1-carbomethoxy-2,3-dihydropyrimidin-4(1H)-one (1). The synthesis employs asparagine as the starting material and provides 1 in 55% yield without the need for chromatographic purification. The structure of 1, as determined by X-ray crystallographic analysis, demonstrates significant pyramidalization at the C4 (carbonyl) and N1 centers, with little evidence of conjugation of N1 with the α,β-unsaturated (vinylogous urea) system

Several new arsinoboranes, wherein boron and arsenic are three coordinate, have been prepared and characterized. They are analogous to B-N and B-P species in which p-p π-bonding, involving the pnictide lone pair and the empty boron p-orbital, may occur. The main conclusion or these studies is that B-As π-bonding, although inherently strong, is difficult to achieve because or the larger inversion barrier at arsenic. Nontheless, very electropositive or bulky substituents at arsenic reduce this barrier surfficiently to observe substantial B-As π-interactions

The synthesis of a number of highly substituted cyclohexane derivatives has been accomplished in a single step reaction of benzyl cyanides and chalcones (1: 2) using sodium ethoxide in anhydrous diethyl ether at room temperature to give 3-aroyl-1,2,4,6-tetraaryl-4-hydroxycyclohexanecarbonitriles. An unambiguous structural assignment was achieved from the analytical and infrared, 1 H NMR and 13 C NMR spectroscopic data as well as X-ray crystallography

In this study, an extension of the intramomecular nitrile oxide-olefin cycloaddition reaction is reported for the facile synthesis of furo[3,4-c]isoxazoles (5) which are in turn shown to be useful precursors to 3,4-disubstituted or 3,4,5-trisubstituted isoxazole derivatives (6). The method consists of a high-yield preparation of a broad spectrum of furo[3,4-c]isoxazoles by intramolecular nitrile oxide-alkyne cycloaddition of acetylenic nitro ethers (3), in turn prepared by Michael addition of various propargylic alkoxides (2) to appropriate nitro olefins (1)

From the meal-promoted oxidative cyclization of several 1,19-disubstituted a,c-biladiene dihydrobromide salts, a number of novel macrocycles were prepared. For example, the cyclization of 1,19-bis(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-ocamethyl-a,c-biladiene dihydrobromide salt (10) with copper(II) aceate afforded copper(II) 20-((methoxycarbonyl)methyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-ocamethyl-1,20-dihydroporphyrin (13) (39% yield), which, upon demetalation, yielded the meal-free 20-((methoxycarbonyl)methyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-ocamethyl-1,20-dihydroporphyrin (14) (48% yield). Using chromium (III) hydroxy acetate as the oxidant (in place of copper II), 1,2,3,7,8,12,13,17,18-nonamethyl-1,20-dihydroporphyrin (5)(55-62%) was obtained from the 1,2,3,7,8,12,13,17,18,19-decamethyl-a,c-biladiene salt (3). Mechanisms of macrocycle formation from a,c-biladiene salts, promoted by either copper (II) or chromium (III), appear to proceed via pathways closely resembling the electrochemical cyclization reaction of 1,19-dimethyl-a,c-biladiene salts

(2-Nitro-5,10,15,20-tetraphenylporphyrinato)nickel(II) reacts with α-isocyanoacetic esters in the presence of DBU to give the first β-fused pyrroloporphyrins, the pyrrole ring in the fused system being shown to undergo typical pyrrole-type chemistry; the corresponding zinc(II) complex affords a novel cyclopropanochlorin (characterized by X-ray crystallography), when treated with an α-isocyanoacetic ester.

The o-nitrophenylselenoethyl functionality is a useful protected vinyl group in porphyrins and chlorins, and its use is demonstrated in the Vilsmeier formylation reaction which has been shown to adversely affect unmodified vinyl groups in tetrapyrrole systems. The X-ray crystal structure for 3-(2-o-nitro-phenylselenoethyl)-3-devinylchlorin-e6 trimethyl ester 14 is reported.

A new barium copper phosphide compound, BaCu10P4, was synthesized by reacting stoichiometric amounts of the elements at 1200 °C for 24 h. BaCu10P4 crystallizes in the monoclinic space group C2/m, with unit cell dimensions a = 23.288(4) b = 3.9070(10), and c = 9.534(2) A and β = 92.26(2)° (Z = 4). The structure can be described as consisting of chains of edge-shared Cu4 tetrahedral prisms that are knitted together by P atoms. The structure is related to BaCu8P4, which can be described in a similar fashion. Temperature-dependent resistivity measurements indicate that BaCu10P4 is a metal. Extended Huckel band calculations are consistent with metallic character for BaCu10P4 through Cu−Cu interactions. Orbitals at the Fermi level show Cu−Cu bonding overlap. On the other hand, BaCu8P4 reveals extremely weak Cu−Cu interactions, but rather optimizes Cu−P bonding.

This article encompasses: (1) an update on recent developments on transition metal/fullerene adduct formation, (2) the use of metal complexes to form ordered crystalline adducts of fullerenes for study by X-ray diffraction, (3) the characterization of fullerene oxides, and (4) the formation of redox active films from fullerene oxides and from fullerenes.

An efficient, diastereoselective route to 2, 5, 6, 7-tetra-substituted 1H-purrolo[1,2-c]imidazoles has been developed using azomethine ylide cycloaddition and urea cyclization reactions. Relative stereochemical assignments at the four contiguous pyrrolidine stereogenic centers were established by single-crystal X-ray analysis.

Exploiting 1,3-dipolar cycloaddition and urea → hydantoin cyclization transformations, novel spiro[cyclopenta[d]isoxazole-4‘,5-imidazolindine] heterocycles of generalized structure I have been prepared. The 1-amino-3-cyclopentenecarboxylate precursor II was prepared from a suitably activated/protected derivative of glycine and the bis-alkylating agent cis-1,4-dichloro-2-butene.

The helical diketone, C36H14O2, is formed during the flash vacuum pyrolysis of decacyclene in the presence of oxygen and has been characterized by X-ray crystallography.

Colorless crystals of the cyclic trigold(I) complex, Au 3 (CH 3 OCNCH 3 ) 3 , that have previously been irradiated with low energy ultraviolet light, emit bright flashes of yellow light when they make contact with a solvent such as chloroform or acetone. Spectroscopic data as well as information on solvoluminescence for this trinuclear complex are presented herein. The origin of the solvoluminescence is considered in the context of the solid state structure of the complex which shows that these triangular complexes pack to form extended trigonal prismatic columns.

Rare-earth transition metal compounds Yb14MnSb11 and Yb14MnBi11 have been prepared by heating stoichiometric amounts of the elements at 1000−1200 °C. These compounds are isostructural with the Zintl compound Ca14AlSb11 and crystallize in the tetragonal space group I41/acd (Z = 8). Single-crystal X-ray data (143 K) were refined for Yb14MnSb11 [a = 16.615(2) A, c = 21.948(4) A, V = 6059(2) A3, and R1/wR2 (0.0299/0.0479)] and Yb14MnBi11 [a = 17.000(3) A, c = 22.259(6) A, V = 6433(2) A3, R1/wR2 (0.0631/0.133)]. Structural analysis is consistent with Yb2+. Temperature-dependent magnetic susceptibility data show that Yb14MnSb11 orders ferromagnetically at 56 K and Yb14MnBi11 has a ferromagnetic transition at 58 K and another transition at 28 K. High-temperature magnetic susceptibility data can be fit with a modified Curie−Weiss law and give μeff = 4.92(2)μB and μeff = 4.9(1)μB for the Sb and Bi compounds, respectively. This result is consistent with the assignment of Mn3+ (d4) and Yb2+ (f 14). Single-crystal ma...

A cyclohexanone intermediate to be employed in the synthesis of the marine natural product N-methylwelwitindolinone C isothiocyanate has been prepared. The synthesis is diastereoselective for the production of the C12 quaternary center, which is obtained via a conjugate addition reaction directed by an adjacent chiral, nonracemic ketal. A single crystal X-ray analysis of a derivative of the final product established the absolute stereochemistry at C12.

A strategy for the efficient synthesis of novel bis-isoxazolo substituted piperidinones has been developed. The protocol consists of the Michael addition of an unsaturated alkoxide to β-nitrostyrene followed by an intramolecular nitrile oxide cycloaddition (INOC) or an intramolecular silyl nitronate olefin cycloaddition (ISOC) to give III. Grignard addition to this isoxazoline intermediate followed by DCC coupling of the resulting isoxazolidine with nitroacetic acid gave II, and a second intramolecular cycloaddition via 1,3-dipoles result in the formation of the targeted novel tetracycles (I). A solid-supported scavenger was employed to increase the efficiency and yield of the Michael addition step.