Stereoselectivity of formation of polycyclic ferrocenyl-4,5-dihydropyrazoles based on E- and Z-s-cis-α,β-enones

Reaction of E- and Z-isomeric 2-ferrocenylmethylidene-1-tetralone, 2-ferrocenylmethylidene-3-quinuclidinone, 1-methyl-3-ferrocenylmethylidene-4-piperidone and 2-ferrocenylmethylidenetropinone with hydrazine proceeds stereospecifically with the formation of the same diastereomeric polycyclic ferrocenyldihydropyrazoles independently of the geometric configuration of the starting α,β-unsaturated ketones. X-ray structural analysis is presented for the trans-diastereomer of 4-acetyl-3-ferrocenyl-1,4,5-triazatricyclo[5.2.2.02,6]undec-5-ene.