Synthesis of four diastereomeric 3,5-dialkoxy-2,4-dimethylalkanals by a simple extension of the non-aldol aldol process to bis(propionates)

[formula: see text] The synthesis of all four diastereomers of bis(propionates), 3,5-dialkoxy-2,4-dimethylalkanals, by non-aldol aldol chemistry is described. The epoxy alcohols (3, 4) were converted into the mesylates (9, 11) which were cleanly rearranged to the desired 3,5-bis(oxygenated)-2,4-dimethylalkanals (10, 12) in high yield. The epoxy mesylates (13, 16) gave the desired products (14, 17) in good yield on treatment with TMSOTf and a hindered base.     

The photoelectron spectrum of HCP and comments on the first photoelectron band of HCN

The photoelectron spectrum of HCP has been obtained, Ionization potentials are found at 10.79 ± 0.01 eV (X² Π) and 12.86 ± 0.01 eV (A ² Σ). By comparison with HCP, a new interpretation of the first photoelectron band of HCN has been proposed which involves a Renner-Teller interaction in the Σ⁺ vibronic states of the molecular ion.     

Novel solid-phase synthesis of 1,2-dialkoxyindoles

[reaction: see text] A novel solid-phase synthesis of 1,2-dialkoxyindoles on SynPhase lanterns is described. A unique C-C bond formation involving a nucleophilic displacement of a solid-bound aryl fluorine by dimethyl malonate afforded the arylnitro methyl ester, which upon treatment with tin(II) chloride dihydrate gave the N-hydroxyindolone. Alkylation of the N-hydroxyindolones afforded the corresponding N-hydroxy-2-alkoxyindoles, which were further alkylated to give the 1,2-dialkoxyindole. A library of 64 (8R(1) x 8R(2)) discrete 1,2-dialkoxyindoles was prepared using a color encoding technique on SynPhase A-series lanterns.     

One-Pot Formation of Carbonates from the Reactions of Carbonyl Compounds with Samarium Diiodide and Methyl Chloroformate

Treatment of carbonyl compounds with SmI₂ and methyl chloroformate in the presence of molecular sieves provides the cyclic carbonates or biscarbonates of pinacols. This one-pot reaction proceeds rapidly even with aliphatic ketones. The stereochemistry obtained by this procedure is different from that of conventional pinacolic couplings.     

Fast peroxyoxalate chemiluminescence for minimized analytical separation systems

The maximum intensity, Imax, and time required to reach the maximum emission, taumax, for 1-aminopyrene monitored in 1,1'-oxalyldi-4-methylimidazole (OD4MI) chemiluminescence (CL) reactions are approximately 61 times higher and 16 times faster than their respective values for bis(2,4,6-trichlorophenyl)oxalate (TCPO) CL reactions in the presence of imidazole (ImH).     

Mössbauer Spectroscopic Studies of Ferrocenylaldimines and their TCNQ Complexes

A series of ferrocenylaldimines (Fc-CH=N-R) has been prepared by Schiff base condensation of formylferrocene with polyacenylamines RNH₂ where R = naphthyl, 5,6,7,8-tetrahydronaphthyl, anthracenyl, and pyrenyl groups. This step was followed by oxidation with TCNQ to give [Fc-CH = N-R][TCNQ]² salts. The electronic state of iron in these compounds was investigated by means of⁵⁷Fe Mössbauer spectroscopy.     

Asymmetric induction in mixed [2 + 2] photoadditions employing a chiral auxiliary in the alkene component

Asymmetric induction was achieved in the photoaddition of 3-methyl-2-cyclohexenone to optically active enoates 1a–c and the absolute configuration of the major adduct was determined.     

Cumulative subject index volumes 41–45

Orbital correlation diagrams for the black phosphorus to A7 (arsenic) phase transformation for various points in the Brillouin zone are presented and analyzed in symmetry terms. The level doublings observed at the black phosphorus geometry for several points are directly attributable to the nonsymmorphic nature of the space group (Herring's theorem). Doublings observed at the A7 structure derive from the choice of a four-atom, rather than two-atom, unit cell to view the geometrical transformation. The space group requirements at the beginning and end points of the transformation process simply control the form of orbital correlation diagrams. In general, $\text{HOMO}\text{LUMO}$ crossings are found at $\text{k = (}\text{1}\text{2}\text{,α,β)}$ where bonds are made and broken along the x direction, a result with simple analogies to more easily visualized one-dimensional problems.     

Mass spectral study of ring E of taraxasterol and compounds with similar ring substitution

The origin of the [M–69]⁺ and [M–111]⁺ signals in the mass spectrum of taraxasterol was studied through the use of C(18), (19), (21), (22) and/or (30) deuteriated derivatives. The generality of these signals for ring systems with an exocyclic methylene group and a methyl moiety on an adjacent carbon was verified with 2-methylmethylenecyclohexane, 1-methyl-2-methylene-trans-decalin, 1,10-dimethyl-2-methylene-trans-decalin and some of their deuteriated derivatives. The most plausible mechanism for the formation of the [M–69]⁺ ion appears to involve cleavage of both bonds allylic to the exocyclic methylene group with a 1,3-hydrogen transfer from the adjacent ring. Genesis of the [M–111]⁺ ion is more complicated but a five-membered allylic ion generated from ring D is proposed.     

Lanthanide triflate-catalyzed three component synthesis of alpha-amino phosphonates in ionic liquids. A catalyst reactivity and reusability study

The catalyst reactivity and reusability for the lanthanide triflate-catalyzed three component synthesis of alpha-amino phosphonates have been examined in room temperature ionic liquids, [bmim][X], in which the catalytic activities were very dependent on the counter anion, X, as well as on the phosphorus nucleophile, and moreover, the catalyst immobilized in an ionic liquid was reused several times without any loss of activity.