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Das in vielen organischen Losungsmitteln gut losliche Natrium-bis(trimethyIsily1)amid (2) eignet sich ausgezeichnet als Base zur Darstellung lithiumsalzfreier AlkylidentriphenylphosphoranLosungen, die fur alle bekannten Ylidreaktionen eingesetzt werden konnen. Als Beispiele solcher Reaktionen werden die cis-stereoselektive Wittig-Reaktion, die C-Acylierung mit Thiolestern und die RingschluBreaktion durch kombinierte inter-und intramolekulare C:-Alkylierung beschrieben. Reactions of Alkylidenetriphenylphosphoranes, XXXIll ') Preparations of Lithiumsaltfree Ylidsolutions with Sodium bis(trimethylsilyl)amide as BaseSodium bis(trirnethylsi1yl)amide (2) which is soluble in many organic solvents is a very useful base for the generation of lithiumsaltfree solutions of alkylidenetriphenylphosphoranes. With these solutions all known ylidreactions can be carried out. cis-Stereoselective Wittig reactions, Cacylations with thiolesters and the ring closure reaction by combined inter-and intramolecular C-alkylation are described.Reaktionen mit Alkylidenphosphoranen (Phosphinalkylenen) laufen in vielen Fallen nur dann in iibersichtlicher Weise und stereoselektiv ab, wenn man sie in lithiumsalzfreien Losungen durchfuhrt *). Solche Ylidlosungen wurden bisher am besten nach der Natriumamidmethode gewonnen'). Wir haben nun gefunden, daD sich das in vielen gebrauchlichen Solventien losliche Natrium-bis(trimethylsily1)amid (2) 3, vorziiglich eignet, um aus Phosphoniumsalzen (I) die korrespondierenden Alkylidenphosphorane (4) in Freiheit zu setzen.Die somit auf besonders einfache Weise erhaltlichen lithiumsalzfreien Ylidlosungen konnen nach unseren bisherigen Erfahrungen zu allen bekannten Ylidreaktionen *) ') '" XXXII.

We have investigated the relationship between energy metabolism, NMDA‐receptor antagonism, and anoxic damage in vitro. Anoxic damage was assessed by measuring protein synthesis, defined as the incorporation of [14C]lysine into perchloric acid‐insoluble tissue extracts. The concentrations of energy metabolites were measured by ion‐exchange HPLC. Anoxia caused an inhibition of protein synthesis, a reduction in phosphocreatine and adenosine triphosphate, and extensive neuronal damage. The reduction of protein synthesis depended on the duration of anoxia and the time allowed for recovery. Preincubation with the creatine dose‐dependently (0.03–3 mmol/L) increased baseline levels of phosphocreatine, reduced the anoxia‐induced decline in phosphocreatine and adenosine triphosphate, prevented the impairment of protein synthesis, and reduced neuronal death. Incubation with (R,S)‐3‐guanidinobutyric acid, a synthetic analogue of creatine that cannot be phosphorylated, did not prevent the anoxia‐induced impairment of protein synthesis and did not enhance the levels of phosphocreatine and adenosine triphosphate. Incubation with a combination of both creatine and the noncompetitive NMDA antagonist MK‐801 provided complete protection. These results indicate that energy status is a major factor controlling anoxic damage in the rat hippocampal slice.

Ausgehend von Isoamylbromid (1) IaDt sich das Isooctyltriphenylphosphoniumbromid (6) darstellen, dessen korrespondierendes Y lid mit Undecanal(8) in stereoselektiver Wittig-Reaktion das (2)-2-MethyI-7-octadecen (9) ergibt. Die Epoxidierung von 9 mit m-Chlorperbenzoesaure liefert 11, den Sexuallockstoff des Schwammspinners. Pheromones, X '1 A Stereoselective Synthesis of (Z)-7,8-Epoxy-2-methyloctPdecpae (Disparlure)starting from isoamylbromide (1) isooctyltriphenylphosphonium bromide (6) can be prepared. The corresponding ylide gives in a stereoselective Wittiy Reaction with undecanal(8) (2)-2-methyl-7-octadecene(9). Epoxidation of9gives rise to formation of 11, the sexpheromone of the gypsy moth.

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