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The reaction of β-stannyl acrylates with carbon redicals, generated from the corresponding bromides, to afford β-alkyl acrylates is the key carbon–carbon coupling step in a synthesis of the fungal dienyl isonitrile antibiotic (1).

Photolysis of the cyclobutanones (5) and (6) in methanol gave the cyclic acetals (10) and (11) and the alkenes (18) and (19); irradiation of (5) and (6) in an aqueous solution gave the lactols (14) and (15), respectively, with only small quantities of the corresponding alkenes.

The acetal (4), prepared by a novel route, was converted into the ketone (6); this ketone furnished the known lactol (7) on photolysis in aqueous acetonitrile.

Alkyl radicals add to the tri-n-butylstannyl substituted terminus of several alkenes; elimination of the stannyl radical results in a preparatively useful, carbon–carbon bond forming reaction, under mild and neutral conditions.

Determination de la conformation des cations formes par ionisation des dimethyl-1,1 methano-3,4 tetrahydro-1,2,3,4 naphtalene-2ols substitues en 2, a l'aide d'une methode basee une equation de difference de constante de couplage

A method is described for the preparation of relatively concentrated (c.1 M) solutions of alkyl carbocations in SbF5-SO2ClF suitable for 13C n.m.r, investigations. This method, which uses syringe techniques, allows the quantitative conversion of precursors, which are soluble in SO2CIF at -78o, into the corresponding cations. The carbocations prepared in this way include isopropyl (1), t-butyl (2), 1,l-dimethylpropyl (3) 1,l-dimethylbutyl (4), 1-ethyl-1-methylpropyl (5), 1,1,2-trimethylpropyl (6), 1-methylcyclopentyl (7), 1,2-dimethylcyclopentyl (8), 2-norbornyl (10), 2-methylnorbornyl (11) and 1-methyl-1-phenylethyl(12). Other methods were needed to generate the bicyclo[3,3,0]octyl(9), 1-adamantyl (l3), 2-methyladamantyl(14) and benzhydryl(l5) cations. 13C parameters are given for all the cations.

Dissolution of the cyclopropabenzene (1) in fluorosulphonic acid results in ionisation and formation of the aromatic cation (2a); with antimony pentachloride, compound (1) affords an orange solid which is proposed as the salt (2b).