Lena Ruı́z Ramı́rez

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.

Regioselectivity of alkylation of the naphthalene fragment in the opening of a small ring in 3-ferrocenyl-3-(1-naphthyl)cyclopropene, Z-2-bromo-1-ferrocenyl-1-(1-naphthyl)cyclopropane, and 1-ferrocenyl-1-(1-naphthyl)cyclopropane

Abstract The opening of a small ring in 3-ferrocenyl-3-(1-naphthyl)cyclopropene (thermolysis, action of HBF4·Et2O or CF3SO3H), Z-2-bromo-1-ferrocenyl-1-(1-naphthyl)cyclopropane (action of AlCl3), and in 1-ferrocenyl-1-(1-naphthyl)cyclopropane (action of Ph3C+BF4−) is accompanied by the alkylation of only the naphthalene fragment giving rise to 1-ferrocenyl-9bH-benzo[e]indene or 1-ferrocenyl-3H-benzo[e]indene. This is connected with a ‘non-bisecting’ position of the naphthalene fragment relative to the three-membered cycle in the starting compounds. The compound 1-ferrocenyl-9bH-benzo[e]indene gives [4+2]-cycloadducts with N-phenyl(azodicarboximide) and N-phenylmaleimide. X-ray structural data are presented for 3-ferrocenyl-3-(1-naphthyl)cyclopropene and its adduct with 1,3-diphenylisobenzofuran, Z-2-bromo-1-ferrocenyl-1-(1-naphthyl)cyclopropane, and 1-ferrocenyl-1-(1-naphthyl)cyclopropane.

Synthesis and some chemical properties of 3-ferrocenyl-3-isopropylcyclopropene: 3-ferrocenyl-3-isopropylstructures of cyclopropene and its adducts with 1,3-diphenylisobenzofuran

Abstract X-ray structural analysis allowed the molecular conformation of 3-ferrocenyl-3-isopropylcyclopropene to be established, where the ferrocenyl fragment occupies a bisecting position relative to the three-membered ring. Some heterolytic cleavage of a σ CC bond in cyclopropene was observed. As a result, predominantly linear products are formed: 1,1-dimethyl-2-ferrocenyl-1,3-butadiene, 3-ferrocenyl-4-methyl-2-pentene, 3-ferrocenyl-4-methyl-3-pentenine and also 3-isopropyl-1H-cyclopentaferrocene. Cyclopropene forms a classical Diels–Alder adduct with 1,3-diphenylisobenzofuran and an adduct with the intermediate 3-isopropyl-1,2-(1-propene-1,3-diyl)ferrocene. X-ray structural data of exo -1,5-diphenyl-3- anti -ferrocenyl-3- syn -isopropyl-6,7-benzo-8-oxatricyclo[3.2.1.0 2,4 ]oct-6-ene are presented.

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.

STRUCTURE OF Z- AND E-2-BROMO-1-FERROCENYL-1-PHENYLCYCLOPROPANES AND 3-FERROCENYL-3-PHENYLCYCLOPROPENE AND THEIR THREE-MEMBERED RING OPENING REACTIONS

Abstract The ring-opening reactions in Z - and E -2-bromo-1-ferrocenyl-1-phenylcyclopropanes and 3-ferrocenyl-3-phenylcyclopropene were studied. It was found that the three-membered ring of the monobromides is opened when treated with AlCl 3 , while that of cyclopropene is opened when boiled in toluene. X-ray structural data of E -2-bromo-1-ferrocenyl-1-phenyIcyclopropane and 3-ferrocenyl-3-phenyl-cyclopropene mono crystals are presented.

Mutual Z-/E-isomerization of ferrocenylmethylene- and arylidene-substituted carbo- and heterocycles

Abstract The treatment of Z -2-ferrocenylmethylene-, Z -2-arylidene-3-quinuclidinones and 3-methylene-quinuclidines, as well as E -3-ferrocenylmethylenecamphor, -menthone, and -cyclohexanone with NaBPh 4 in acetic acid results in their reversible Z -/ E -isomerization. The reaction proceeds via hydroxyallyl and crotyl carbocations with a fixed s - cis -conformation.

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.

3-Methylene-2-ferrocenylmethylenequinuclidine in cycloaddition and dimerization reactions

Abstract Cycloaddition, cyclodimerization, and cationic dimerization reactions of 3-methylene-2-ferrocenylmethylenequinuclidine as a ferrocenyl substituted 1,3-diene possessing a fixed s -cissoidal conformation of the double bond system have been investigated. This prepared diene has been shown to form Diels-Alder adducts with azodicarboxylic and/or maleic acid N-phenylimides. It has been shown also that the diene undergoes thermal [4 + 2]-cyclodimerization and links 3-methyl-2,5-(1-pipyridinium-1,4-diyl)-1-ferrocenylallylic citation. The latter reaction results in formation of an adduct of chain structure. The products of alkylation of N,N-dimethylaniline with the intermediate allylic cation have been isolated and characterized for the first time.

3,3-Diferrocenylcyclopropene

Abstract Dehydrohalogenation of isomeric 2-chloro- and 2-bromo-1,1-diferrocenylcyclopropanes (Z- and E-isomers with respect to the ‘bisecting’ ferrocenyl substituent) under the action of ButOK in DMSO afforded 3,3-diferrocenylcyclopropene. In solution, this underwent facile opening of the small ring to give 3-ferrocenyl-1H-cyclopentaferrocene (∼55%) and 1,1-diferrocenylpropene (15%). The spatial structure of Z-2-chloro-1,1-diferrocenylcyclopropane and 1,1-diferrocenylcyclopropane were elucidated by X-ray diffraction analysis of a single crystal.

Photolysis of 3-methyl- and 3-isopropyl-3-ferrocenylcyclopropenes

Abstract The photochemistry of 3-methyl- and 3-isopropyl-3-ferrocenylcyclopropenes ( 10 and 11 ) has been studied. Upon triplet excitation (sensitized irradiation) both cyclopropenes are dimerized to a tricyclohexane dimers whereas in the singlet state (direct irradiation) cyclopropene 10 is converted to 3-ferrocenyl-3-methylidenepropyne and trans -2-ferrocenyl-2-butene indicating that there is an intermediate vinyl carbene. Cyclopropene 11 is converted to 1-ferrocenyl-4,4-dimethylcyclobutene. Direct irradiation of the mixture of 11 with 2-ferrocenyl-3-methyl-1-butene leads to the formation of 1,3-diferrocenyl-6,6-dimethyl-3-isopropenylcyclohexene ( 24 ). A possible reaction pathway via intermediate radicals is discussed. X-ray structural data are presented for 3,6-diferrocenyl-3,6-diisopropyltricyclo[3.1.0.0. 2,4 ]hexane and compound 24 .