I.p. applicated S(+)-1, R(-)-1 und rac. 1 prolonged hexobarbital sleeping in rats. The rac. 8-chloro compound 3 given i.p. produced no prolongation. Determination of rac. 1 in serum and tissues of rats 30 min after i.p. administration of 50 mg/kg showed that rac. 1 was detectable in serum and brain, yet its concentration was below the limit of determination. I.v. applicated, the enantiomers of 1 and 3 showed diametrically opposite CNS-effects: The S(+)-enantiomers were convulsively active as pentetrazol, whereas the R(-)-enantiomers were CNS depressant active prolonging hexobarbital sleeping time dose-dependently. High doses of diazepam antagonized dose-dependently the convulsive action of S(+)-1 supporting the hypothesis that this enantiomer acted as a strong inverse agonist, whereas R(-)-1 produced weak agonistic activity at the benzodiazepine binding site of the GABA-receptor.--Enantioselective differences for the binding of the 1-enantiomers to human serum albumin were found, too. R(-)-1 was bound to a greater extent than S(+)-1.
Ethoxycarbonyl-1-silacyclobutanes were synthesized by intramolecular C-H insertion of carbenes generated photochemically from a-(di-tert-butylsilyl)-a-diazoacetates; they undergo smooth thermal ring-expansion by a 1,3(C ? O) silyl shift to form 6-ethoxy-1-oxa-2-silacyclohex-5-enes.
Novel α-Silyl-α-diazoacetates Containing a Silicon-Heteroatom Bond.-Silylation of diazoester (II) with the silyl triflates (I) gives the chlorosilyl diazoacetates (III). The latter can be easily transformed to azidosilyl-, isocyanatosilyl-, and isothiocyanatosilyl-substituted derivatives. The analogous chloro(dimethyl)silyl triflate generated from the silyl chloride (IX) and triflic acid, exhibits lower stability yielding a mixture of diazoacetates (X) and (XI).
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