Tatiana Klimova Berestneva

The structure of bicyclic ferrocenylmethylene substituted 2-pyrazolines and their reactions with azodicarboxylic acid N-phenylimide

Abstract Asymmetrical induction in the synthesis of bicyclic pyrazolines with a ferrocenyl substituent has been studied. A relatively high diastereomeric selectivity in the ‘chiral-center-by-a-chiral-center’ induction of the 1,2-type has been observed. Molecular geometry of a cis -diastereomer of 1-acetyl-9-ferrocenyl-4-ferrocenylmethylene-1,2-diazabicyclo[4.3.0]non-2-ene has been established. Bicyclic 2-pyrazolines having conjugated ferrocenylmethylene fragments interact with azodicarboxylic acid N -phenylimide to form diene and monoene adducts.

Formation of acetylenic compounds and ring transformations of 3-alkyl-3-ferrocenylcyclopropenes in the reaction with 1,3-diphenylisobenzofuran

The reaction of 3-ferrocenyl-3-methylcyclopropene with 1,3-diphenylisobenzofuran leads to the formation of exo - and endo -1,4-epoxy-2-ethynyl-2-ferrocenyl-1,4-diphenyltetralines as the main products in addition to the isomeric Diels–Alder exo -adducts. At the same time, 3- tert -butyl- and 3-(1-adamantyl)-3-ferrocenylcyclopropenes form the endo - and exo -adducts of 3-alkyl-1,2-(1-propene-1,3-diyl)ferrocene. The structures of the acetylenic compounds and of the adduct containing a t Bu-substituent are established by X-ray structural analysis. A possible reaction pathway via intermediate zwitter-ion is discussed.

3,3-Diethyl-and 3,3-dibenzyl-1,2-diferrocenylcyclopropenes.

Reactions of 2,3-diferrocenylcyclopropenone 1 with ethyl- and benzylmagnesium chlorides afford 3,3-diethyl-and 3,3-dibenzyl- 1,2-diferrocenylcyclopropenes 2 and 3, respectively, and products of nucleophilic opening of the three-membered ring resulting from the addition of RMgCl to the carbonyl group, viz., saturated ketones(4,5-diferrocenylheptan-3-ones 4a,b and 3,4-diferrocenyl-1,5-diphenylpentan-2-ones 5a,b as ca. 3: 1 mixtures of two diastereomers) and other products. The spatial structures of compounds 2 and 4a were established by X-ray diffraction analysis of single crystals. Protonation of the cyclopropenes 2 and 3 with tetrafluoroboric acid at -40 degrees C yields the corresponding 3,3-dialkyl-1 ,2-diferrocenylcyclopropylium tetrafluoroborates. Transformation of the latter into diferrocenylallylic cations upon increasing the temperature to 20 degrees C and their eprotonation under the action of N,N-dimethylaniline were studied. Electrochemical investigation of 1 and 2 shows that in both complexes the cyclopropene spacer allows electronic communication between the two outer ferrocenyl groups, this being notably greater for 2 than for 1.

Synthesis and some chemical properties of s-cis-diferrocenyltrienes. The role of stereoelectronic factors in cationic dimerization reactions

Abstract Dehydration of 2,6-bis(ferrocenylmethylene)-1-methylcyclohexanol and 2,7-bis(ferrocenylmethylene)-1-methylcycloheptanol gave the corresponding diferrocenyltrienes with a fixed s-cissoidal conformation of the double bond system, viz. 1,3-bis(ferrocenylmethylene)-2-methylene-cyclohexane and -cycloheptane, respectively. These trienes easily afford the products of linear and cyclodimerization by a cationic cyclodimerization mechanism as well as [4+2]-cyclodimers. They also form Diels–Alder adducts with azodicarboxylic and maleic acid N- phenylimides. The latter products undergo stepwise oxidative dehydrogenation on SiO 2 up to the formation of phthalimide derivatives.

Thermolysis and [3+2]‐Cycloaddition Reactions of 2,3‐Diferrocenyl‐ and 2,3,‐Diruthenocenylcyclopropenones

Abstract 2,3‐Diferrocenyl‐ and 2,3‐diruthenocenylcyclopropenone undergo thermolysis at ∼180°C with opening of the small ring via ketenocarbenes. Intramolecular transformation of the latter occurs with elimination of CO to yield dimetallocenylacetylenes. Alternatively, they enter into 1,3‐dipolar cycloaddition reactions with C≡C or C˭C multiple bonds to give cyclopentadienone or cyclopentenone derivatives, respectively.