Synthesis and structure of 1-zirconacyclopent-3-yne complexes without substituents adjacent to the triple bond.

Five-membered metallacyclic alkynes that have no substituents adjacent to the triple bond have been synthesized, isolated, and structurally characterized. Zirconocene dichlorides, Cp'2ZrCl2 (Cp' = C5H5, C5H4-t-Bu), reacted with 1,4-dichlorobut-2-yne in the presence of magnesium to give 1-zirconacyclopent-3-yne compounds (5 (a) Cp' = C5H5, (b) Cp' = C5H4-t-Bu) that have a -CH2CCCH2- moiety in good yields. They are stable enough to be isolated in a pure form, despite the absence of substituents.

[A case of medial medullary infarction with persistent primitive hypoglossal artery].

A 66-year-old woman was admitted to our hospital because of vomiting, dizziness and vertigo. Neurological examination on admission revealed only upbeat nystagmus without cranial nerve symptoms, paresis, cerebellar signs or sensory disturbances. Magnetic resonance(MR) images demonstrated a new T 2 high intensity and T 1 iso-intensity signal lesion in the right upper medial medulla.