Investigations on diazo compounds and azides- LXII.: Synthesis and reactions of a-diazo phosphonates with a conjugated 1,3-diene unit

α-Diazo phosphonates with a conjugated 1,3-diene unit are synthesised by the Bamford-Stevens reaction ($\text{2}$ →$\text{4}$→$\text{3}$). They undergo [4+2]-cycloadditions with the dienophile $\text{5}$ to form the tetrahydrotriazolopyridazines $\text{8}$, which possess an unchanged diazo group. In contrast, dimethyl acetylenedicarboxylate ($\text{9}$) reacts exclusively with the diazo dipole of $\text{3}$ to yield the 3H-pyrazoles $\text{10}$, which rearrange to $\text{11}$ by sigmatropic PO-shifts and hydrolyse to form $\text{13}$. The diazo compound $\text{3b}$ isomerises to the pyrazole $\text{16}$ when heated in benzene.     

Beitrag zur Massenspektrometrie substituierter α, ω-Alkandiamine. 29. Mitteilung über massenspektrometrische Untersuchungen

Contribution to the mass spectrometry of substituted α,ω-alkane diamines The main mass spectral fragmentation pattern of compounds of types 1 to 4 is discussed. After loss of C₆H₅ · CH₂ · from the molecular ion the acid correspondin to the N,N-disubstituted residue is splitted off. The mechanism of this fragmentation reaction depends on the member of CH₂-groups between the two nitrogen atoms (Schemes 1 and 3) and on the substitution pattern of both nitrogens (Scheme 2).     

Far infrared spectra of solid molecular nitrogen

This paper reports the observation of the far infrared absorption spectrum of a single crystal of N₂, measured over absorption paths of 4 cm (lengthwise) and 2 cm (across the crystal). The crystal chamber, with quartz windows, was immersed in a flow of cold helium gas. The spectrum from 20 to 120 cm^–1 was recorded in the liquid phase, the-phase, and over the full temperature range of the-phase (35.6–2.0 K) with a Fourier transform spectrometer. The spectral resolution, which was not instrument-limited, and the large path allowed the observation of more detailed multiphonon-transition structure in the spectrum of the-phase than has previously been observed.     

Serendipitous synthesis of a ditwistane: a one-step access!

4-tert-Butyl-2-cyclohexen-1-one dimerizes in THF solution via its kinetic enolate, leading to di-tert-butylditwistane 8 in up to 36% yield (−78 °C → room temp., protonolysis, flash chromatography). X-ray crystallography shows that 8 incorporates one R and one S enantiomer of the starting ketone; none of the diastereomeric ditwistanes epi-8, epi’-8 or iso-8 was isolated. This means that the formation of 8 proceeds with mutual kinetic resolution and 100% induced diastereoselectivity.     

Kopsirachin,ein ungewöhnliches Alkaloid aus der Apocynaceae Kopsia dasyrachis Ridl. 189. Mitteilung über organische Naturstoffe

Kopsirachine, an Unusual Alkaloid from the Apocynaceae Kopsia dasyrachis Ridl. From the leaves of Kopsia dasyrachis Ridl. a new type of alkaloid, kopsirachine ( 1 ), built up from catechin ( 2 ) and skytanthine ( 3 ) has been isolated. The structure elucidationis based on spectral and chemical evidence. Oxidative cleavage of its derivative 4 with KMnO₄ afforded veratric acid wich was identified as its methylester by comparison with an authentic sample. Pyrolysis of 1 yielded δ-skytanthine ( 3 ). The stereochemistry of the skytanthine substituents in 1 could not yet be established.