Asymmetric Induction in the Synthesis of 3,4,5-Trisubstituted Ferrocenyl-4,5-dihydropyrazoles

The asymmetric induction in the synthesis of 3,4,5-trisubstituted 4,5-dihydropyrazoles with ferrocenyl substituents, starting from the E and Z isomers of ,-unsaturated ketones was studied. A high diastereoselectivity was revealed at the 1,2 chiral center chiral center induction, which is independent of the configuration of the starting chalcones.     

Ene Synthesis of Bicyclic Arylmethylenedihydropyrazoles Using 4-Phenyl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione

8-Acetyl-7-aryl-2-arylmethylene-8,9-diaza- and 4,8,9-triazabicyclo[4.3.0]non-9-enes react with4-phenyl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione, following the ene addition pattern. Under similar conditons 7-aryl-2-arylmethylene-8-methyl-8,9-diazabicyclo[4.3.0]non-9-enes give rise to both mono- and polyadditionproducts. The product structures were studied by ¹H and ¹³C NMR, IR, and UV spectroscopy and singlecrystal X-ray diffraction.     

Behavior ofZ- andE-s-cis-ferrocenyl-1,3-dienes in cycloaddition and dimerization reactions

Z-3-Ferrocenylmethylene-2-methylenecamphane andE-2-ferrocenylmethylene-3-methylenequinuclidine were synthesized by isomerization of the corresponding isomericE- andZ-1,3-dienes in an acidic medium. The dienes obtained form [4+2]-cycloadditionendo-adducts withN-phenylmaleimide, do not form cyclodimers upon thermal or acid-catalyzed [4+2]-cyclodimerization, and addZ-3-ferrocenylmethylene-1,2,7,7-tetramethylbicyclo[2.2.1]hept-2-ylium andE-2-ferrocenylmethylene-3-methyl-1-azoniabicyclo[2.2.1]oct-3-ylium salts, respectively, at the terminal methylene group to give linear addition products. The latter undergo fragmentation on treatment with HBF₄ to form the corresponding carbocation tetrafluroborates. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1223–1228, June, 1998.     

Asymmetrical induction in the synthesis of ferrocenyl-substituted bicyclic pyrazolines.E,Z-Isomerization of the ferrocenylmethylidene fragment

Asymmetrical induction in the synthesis of bicyclic ferrocenyl-substituted pyrazolines was studied. High diastereoselectivity of induction of the chiral center by the chiral center of the 1,2 type was observed. Thecis diastereomer of 2-acetyl-3-ferrocenyl-7-ferrocenylmethylidene-2,3,3a,4,5,6,7-heptahydroindazole was studied by X-ray diffraction analysis. TheE,Z-configurational isomerism of the ferrocenylmethylene fragment of pyrazolines in an acidic medium is described. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No.4, pp. 765–770, April, 1999.