L. Ruiz Ramirez

The reactions of semicarbazide and thiosemicarbazide with ferrocenyl-substituted α,β-enones

Abstract Semicarbazide (hydrochloride) and thiosemicarbazide react with α,β-unsaturated ketones of the ferrocene series in excess of t BuOK to give 1-carbamoyl- and 1-thiocarbamoyl(ferrocenyl)-4,5-dihydropyrazoles. The condensation with thiosemicarbazide is accompanied by the fragmentation of the starting α,β-enones resulting in ferrocenecarbaldehyde or acetylferrocene thiosemicarbazones.

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.

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.

2,3-Diferrocenylcyclopropenone in the reaction with organomagnesium compounds

The reactions of 2,3-diferrocenylcyclopropenone with ethyl- and benzylmagnesium chlorides afford 3,3-diethyl- and 3,3-dibenzyl-1,2-diferrocenylcyclopropenes along with products of nucleophilic opening of the three-membered ring: α,β-unsaturated and saturated ketones (cis-1,2-diferrocenylpent-1-en-3-one and cis-1,2-diferrocenyl-4-phenylbut-1-en-3-one, 4,5-diferrocenylheptan-3-one, and 3,4-diferrocenyl-1,5-diphenylpentan-2-one). The products of insertion of intermediate diferrocenyl(vinyl)carbene at one of the σ-bonds of the starting 2,3-diferrocenylcyclopropenone were also isolated: 4-(2-oxo-1-ferrocenylbutyl)- and 4-(2-oxo-3-phenyl-1-ferrocenylpropyl)-2,3,4-triferrocenylcyclobutenones. 3,3-Dibenzyl-1,2-diferrocenylcyclopropene and one of the diastereomers of 4,5-diferrocenylheptan-3-one were studied by X-ray diffraction analysis.

Synthesis of biologically active compounds based on 2-ferrocenylmethylene-3-quinuclidone

Biologically active nitrogen heterocycles (1–7) containing ferrocene and quinuclidine fragments were synthesized. 3-Methylene-2-ferrocenylmethylenequinuiclidine forms adducts withN-phenylimides of azodicarboxylic (the structure was established by X-ray structural analysis) and malefic acids. 3-Methylene-2-fer-rocenylmethylenequinticlidine also undergoes [4+2]-cyclodimerization when heated and adds salts of the 3-methyl-2-ferrocenylmethyleneI-azoniabicyclo[2.2.2]oct-3-yl cation at the terminal methylene group to form a linear addition product.

3-Alkenyl-5-ferrocenyl-2-pyrazolines in reactions with azodicarboxylic acidN-phenylimide

Azodicarboxylic acidN-phenylimide reacts with 1-acetyl-3-(2-ferrocenylethenyl)-5-ferrocenyl-2-pyrazoline according to the [4+2]-cycloaddition mechanism to form a Diels—Alder adduct. Under analogous conditions, 1-acetyl-5-ferrocenyl-3-(1-cyclohexenyl)-substituted 2-pyrazolines containing allylic hydrogen atoms give monoene addition products.

1-Thiocarbamoyl(ferrocenyl)-4,5-dihydropyrazoles

Thiosemicarbazide reacts with aryl β-ferrocenylvinyl ketones and β-arylvinyl ferrocenyl ketones in the presence of ButOK to give 1-thiocarbamoyl-5- and -3-ferrocenyl-4,5-dihydropyrazoles, respectively. The complexes of 3-ferrocenyl-5-phenyl-, 3,5-diferrocenyl-, and 3-ferrocenyl-5-p-methoxyphenyl-1-thiocarbamoyl-4,5-dihydropyrazoles with CuII are described.

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.