C. Alvarez Toledano

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

Abstract 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.

Synthesis and some chemical transformations of 3-ferrocenyl-3-phenylcyclopropene

Crystalline 3-ferrocenyl-3-phenylcyclopropene was obtained by dehydrobromination of 2-bromo-l-ferrocenyl-l-phenylcyclopropane with potassiumtert-butoxide in dimethyl sulfoxide. The compound synthesized undergoes catalytic hydrogenation to l-ferrocenyl-I-phenylcyclopropane, reacts with 1,3-diphenylisobenzofuran to give the expected product of stereospecific [4+2[-cycloaddition and 3-ferrocenylindene, and also undegoes opening of the small ring on treatment with superacids to give 3-ferrocenylindene as the major product. The data of single crystal X-ray diffraction analysis of 1-ferrocenyl-l-phenylcyclopropane and the diene adduct of 3-ferrocenyl-3-phenylcyclopropene with 1,3-diphenylisobenzofuran are given.

Retrocyclization reactions of gem-dibromo(ferrocenyl)cyclopropanes

Abstract Retrocyclization of 1-methyl-, 1-isopropyl-, 1-cyclobutyl-, 1-phenyl-, 1- tert -butyl-1-ferrocenyl-, 1-ferrocenyl-3-methyl- and 1,1-diferrocenyl- 2,2-dibromocyclopropanes ( 2a – g ) under the action of t BuOK in DMSO, which occurs in parallel with reduction and dehydrobromination, is studied. Cyclic dimers of 2-ferrocenylpropene, 2-ferrocenyl-3-methylbut-1-ene, and 1-cyclobutyl-1-ferrocenylethene were obtained upon retrocyclization of compounds 2a – c , respectively, while compounds 2d , e gave linear dimers of 1-ferrocenyl-1-phenylethene and 2-ferrocenyl-3,3-dimethylbut-1-ene upon retrocyclization. Retrocyclization of 2f , g afforded trans -1-ferrocenylpropene and 1,1-diferrocenylethylene, respectively. The action of t BuOK in DMSO on the dibromide 2a in the presence of 1,3-diphenylisobenzofuran resulted in the Diels–Alder adducts derived from 2-ferrocenylpropene and 3-ferrocenyl-3-methylcyclopropene. The structures of 1,2-(1-ferrocenyl-1,3,3-trimethylpropane-1,3-diyl)ferrocene and exo -1,5-diphenyl-3- anti -ferrocenyl-3- syn -methyl-6,7-benzo-8-oxatricyclo[3.2.1.0 2,4 ]oct-6-ene were confirmed by X-ray diffraction analysis.

Stereospecific formation of polycyclic ferrocenyldihydropyrazoles based on Z- and Å-isomeric ferrocenyl-substituted α,β-unsaturated ketones of the heterocyclic series

The reactions of E- and Z-isomeric 2-(ferrocenylmethylidene)quinuclidin-3-one, 1-methyl-3-(ferrocenylmethylidene)piperidin-4-one, and 2-(ferrocenylmethylidene)tropinone with hydrazine proceed stereospecifically to form the same diastereomeric polycyclic ferrocenyldihydropyrazoles regardless of the geometrical configuration of the starting α,β-unsaturated ketones. The structure of the trans-diastereomer of 4-acetyl-3-ferrocenyl-1,4,5-triazatricyclo[5.2.2.02,6]undec-5-ene was established by X-ray diffraction analysis.

Photochemical transformations of 3-alkyl-3-ferrocenylcyclopropenes

Photolysis of 3-ferrocenyl-3-methyl- and 3-ferrocenyl-3-isopropylcyclopropenes was studied. Sensitized irradiation (triplet excitation) afforded [2+2]-cycloaddition products, viz., tricyclohexane derivatives. Direct irradiation (singlet excitation) of methyl-substituted ferrocenylcyclopropene gave rise to 2-ferrocenylbut-1-en-3-yne and trans-2-ferrocenylbut-2-ene. The isopropyl analog was converted into 1-ferrocenyl-4,4-dimethylcyclobutene. The reaction of this cyclopropene with 2-ferrocenyl-3-methylbut-1-ene afforded 1,3-diferrocenyl-3-isopropyl-6,6-dimethylcyclohexene. The latter compound and 3,6-diferrocenyl-3,6-diisopropyltricyclo[3.1.0.02,4]hexane were studied by X-ray diffraction analysis. Possible reaction pathways are discussed.

3-Ferrocenyl-3-(1-naphthyl)cyclopropene. Synthesis, structure, and chemical transformations

Crystalline 3-ferrocenyl-3-(1-naphthyl)cyclopropene was prepared by dehydrobromination ofZ- andE-2-bromo-1-ferrocenyl-1-(1-naphthyl)-cyclopropanes by ButOK in DMSO. The resulting compound and the startingZ-monobromocyclopropane were characterized by X-ray diffraction analysis. The obtained cyclopropene reacts with 1,3-diphenylisobenzofuran to give a [4+2]-cycloadduct. The small ring opens upon treatment with HBF4 etherate to afford isomericZ- andE-prop-1-enes and 1-ferrocenyl-3H-benzo[e]indene. Thermolysis of this cyclopropene results in the formation of 1-ferrocenyl-9bH-benzo[e]indene. In all cases, opening of the small ring is accompanied by exclusive alkylation of the naphthalene moiety.

Transformations of spirocyclodimers of 1,3-bis(ferrocenylmethylidene)-2-methylidenecycloalkanes in acid medium

An intramolecular homoannular alkylation of one ferrocenyl substituent in spirocyclodimers of 1,3-bis(ferrocenylmethylidene)-2-methylidenecyclohexanes and -cycloheptanes on treatment with trifluoroacetic acid, leading to the formation of polyfused products containing a three-petal system of six-membered rings in the molecule center, was found. The structure of 11-ferrocenyl-6,14-bis(ferrocenylmethylidene)-2,3-ferroceno-1,2-tetracyclo[8.8.0.05,10.013,18]octadeca-2,13(18)-diene was established by X-ray diffraction analysis.