SCF-Xα-SW calculation on the molecule N2 using theoretical αta

The first calculation of a molecule, N₂, by the SCF -Xα-SW method using the theoretically derived parameter α_ta is reported.     

Absolute Konfiguration der enantiomeren α-CyclogeraniumsäUren, α-Cyclogeraniale, α-Jonone, γ-Jonone, α-und ϵ-Carotine

By chemical correlation with manool and ambrein the absolute configurations of the enantiomeric α-cyclogeranic acids, α-cyclogeranials, α-ionones and α- and ?-carotenes have been elucidated.     

IR- und RAMAN-Spektren von CuN3, AgN3, TIN3, BiON3, Cu(N3)2 und α-Pb(N3)2

IR- and RAMAN Spectra of CuN₃, AgN₃, TlN₃, BiON₃, Cu(N₃)₂, and α-Pb(N₃)₂ The vibrational spectra of the title compounds were recorded and assigned with respect to their crystal structure. The RAMAN spectra mere obtained in aqueus sus-pension.     

Syntheses of methyl α-dl-mycaminoside, methyl α-dl-oleandroside, methyl β-dl-cymaroside, methyl α-dl-tyveloside and methyl α-dl-chromoside C

Five rare hexoses, which are components of antibiotics or cardiac glycosides, have been synthesized as methyl glycosides through a common intermediate methyl 2,3-dehydro-2,3,6-trideoxy-α-dl glucopyranoside (7). Epoxidation and subsequent treatment with dimethylamine of7 afforded methyl α-dl-mycaminoside (9). The addition reaction of MeOH to12 gave methyl α-dl-oleandroside (15) and methyl β-dl-cymaroside (17). The hydroxymercuration and subsequent reduction of12 afforded methyl α-dl-chromoside C (19) and methyl β-dl-tyveloside (25).     

The reactions of C(α), O-dilithiooximes,C(α), N-dilithiophenylhydrazones,and C(α), N,N-trilithiohydrazones with diethyl oxalate to give biisoxazoles,bipyrazoles, and pyridazones

Several C(α), O-dilithiooximes were condensed with diethyl oxalate and acid-cyclized to give biisoxazoles. Only dilithio p-fluoroacetophenone phenylhydrazone gave the bipyrazole when condensed with this diester. Other C(α), N-dilithiophenylhydrazones and several C(α), N,N-trilithio-hydrazones were condensed with diethyl oxalate and acid-cyclized to give the intramolecular 4-hydroxy-3-pyridazones. Several non-cyclized intermediates were isolated and a reaction mechanism is presented.     

NMR chemical shift substituent effects: 2-α-monosubstituted N,N-diethylacetamides

¹H NMR chemical shifts for some α-hetero-substituted N,N-diethylacetamides were recorded. The resonance assignments for the syn- and anti-methylene and -methyl protons have been made unambiguously through their aromatic solvent induced shifts and are opposed to the literture assignments for the N-methylene protons. An empirical relationship between the Charton polar (σ_L) and steric (V) parameters and the α-methylene proton resonances was found. The N-methylene proton chemical shifts also showed a qualitative dependence on the α-substituent electronegativity, while the N-ethyl methyl proton chemical shifts were related to the α-substituent steric effects. The Paulsen and Todt anisotropic model and the more populated rotamers proposed seem to explain the results very well.     

Transformations of N-heteroarylformamidines into derivatives of β-heteroarylamino-α,β-dehydro-α-amino acids, β-heteroarylamino-α-amino acids,and dipeptides

Transformations of N'-heteroaryl-N,N-dimethylformamidines 1 as a general method for the preparation of β-heteroarylamino-α,β-dehydro-α-amino acids, β-heteroarylamino-α-amino acid derivatives 5–9 , and dipeptides 10 , are described.     

α-Alkyl-α-Amino-β-Lactam Peptides: Design,Synthesis, and Conformational Features

Remarkable asymmetric induction is achieved in the alkylation of the lithium enolate of the β-lactam 1 . This allows the first time access to a new family of peptidomimetics 2 with predictable conformational constraints.