Coherent π− production in He3 + Li6 → π− + X at 303 MeV/N

The production of pions by the He³ nucleus is calculated in the Weizsäcker-Williams approximation. The pion cloud of the He³ nucleus acts like a beam of pions scattering incoherently on the Li⁶ nucleus. The size and energy dependence of the observed π-cross section at 0° degrees is in good agreement with this theoretical model.     

Aggregative activation in heterocyclic elimination - additions I. Dehydro dihydropyran nucleophilic condensations

It is shown that by nucleophilic Aggregative Activation of NaNH₂, dehydro dihydropyrans may. be easily generated and condensed with ketone enolates in good yields.     

Zur Reaktion von BaBiSe3 mit dem Cryptanden [2.2.2] in Ethylendiamin Darstellung und Kristallstruktur von [Ba-222Crypt]Se4 · en

Reaction of BaBiSe₃ with 2.2.2-Crypt in Ethylenediamine. Preparation and Structure of [Ba-222Crypt]Se₄ · en The new compound [Ba-222Crypt]Se₄ · en crystallizes in the monoclinic system, space group P2₁/n with lattice constants see ?Inhaltsübersicht”?. Significant structure units are hitherto unknown Se₄^2? anions.     

Disproof of the Overall Enzymatic Biosynthesis of Vindoline from Tryptamine and Secologanin by Cell-Free Extracts from the Leaves of Catharanthus roseus (L.) G. DON

A cell-free extract, which was isolated from the leaves of mature Catharanthus roseus plants by a previously published procedure, does not convert a mixture of secologanin and radiolabelled tryptamine to vindoline, as was recently claimed. The radioactivity in the purified alkaloid extract determined by earlier workers is certainly due to ‘impurities’ in the presumed ‘vindoline’. This was shown by extensive purification of the alkaloid extract (which contained added unlabelled vindoline as a carrier) followed by chemical conversion of vindoline to two derivatives and subsequent purification, ultimately giving unlabelled deacetylvindoline.