Preparation, properties, and reactions of the new q-cyclopentadienyl(dio1efin)nickel complexes will be reported in detail elsewhere.
Tris(v]-methylcyclopentadieny1)dinickel tetrajuoroborate (26)A 50% aqueous solution of HBF, (0.4 ml) is added very slowly with exclusion of air to a solution of (lb) (650 mg, 3 mmol) in propionic anhydride (5 ml). After brief mixing the resulting dark brown solution is carefully added dropwise to vigorously stirred diethyl ether (75 ml). The blackish violet, finely crystalline precipitate is isolated by filtration through a G 3 frit and washed several times with ether. Vacuum drying affords 620 mg of (2b) (93% yield based on (Ib)).
aqueous phase was extracted several times with ether, and the combined ethereal layers were dried over Na,SO, and evaporated in a vacuum. The oily residue solidified after some hours to well-formed crystals that were filtered off cycloheptyne ( 2 ) could not be isolated-it has a half-life in 0.016 M CH,Cl, solution ofless than a minute at -25°C and of about an hour at -76"Cr31. We therefore posed ourselves the question whether introducing two geminal Table 1. Compounds of the type RR'P(S)SX synthesized.
Beide Methoden, die sich im Eintopfverfahren durchfuhren lassen, eignen sich auch zur Herstellung von Isothiocyanatoacyl-oligopeptiden. Bei der Umsetzung von Glycylglycin nach Methode 2 zeigte sich, dalj zwar die Sauren (7) nicht jedoch die a-Isothiocyanatoacyl-aminosauren (8) bei Raumtemperatur bestandig sind, da schon bei 0°C Ringschlulj zum Thiohydantoin ( 9 ) erfolgt. A-C, O
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