C. Peter Lillya

Stereospecific synthesis of dienone iron tricarbonyl complexes by friedelcrafts acylation

Abstract Acylation of diene Fe(CO) 3 complexes using the Perrier complexes RCOCl/AlCl 3 in methylene chloride at 0°C gives dienone complexes in high yield. Substitution occurs only at unsubstituted terminal carbons of the diene unit. Quenching the reaction mixtures in cold aqueous ammonia gives cis dienone complexes only. Trans dienone complexes are prepared by subsequent isomerization in methanolic sodium methoxide. Formylation of diene Fe(CO) 3 complexes proceeds in modest yield using dichloromethylmethyleter/AlCl 3 in methylene chloride to give trans -dienal complexes. Reduction of the dienone and dienal complexes as well as those of dienols and dienoic esters with 4 : 1 AlCl 3 /LiAlH 4 results in complete removal of the oxygen function to give trans -diene complexes in good yield.

Reactivity of dienetricarbonyliron compounds in friedel—crafts acylation

Abstract Relative reactivities for substituted dienetricarbonyliron compouds toward the methyloxocarbonium tetrachloroaluminate ion pair in dichloromethane have been determined by a competition method. Substituent effects are generally small. However, substituted carbons are not attacked themselves, and acyl groups are strongly deactivating. Some diene complexes which give low yields of acylation product react rapidly with the electrophile nevertheless. These data require that formation of the transition state for electrophilic attack causes small decreases in electron density at the diene carbons. Our data along with data from the literature seem most consistent with rate determining electrophilic attack at carbon.

Protonated ketones as NMR models for organotransition metal cations

Abstract A study of ferrocenyl ketones in CDCl 3 /SO 2 /FSO 3 H solution at low temperature has shown that these protonated ketones are excellent NMR models for the corresponding ferrocenylcarbinyl cations. Comparison of the results of a similar study of tricarbonyl( trans,trans -dienone)iron complexes to the limited NMR data available for the corresponding tricarbonyl ( trans -π-pentadienyl)iron cations suggests strongly that the protonated ketones are good models for the latter cations also. A qualitatively similar pattern of downfield NMR shifts as that observed on protonation of dienone-Fe(CO) 3 complexes is caused by oxidation of dienol-Fe(CO) 3 complexes to dienone-Fe(CO) 3 complexes. These data are interpreted as favoring a conjugative mechanism for stabilization of ferrocenylcarbinyl and tricarbonyl ( trans -π-pentadienyl)iron cations as opposed to one involving neighboring group participation by iron. Owing to exchange with free fluorosulfonic acid, NMR signals for hydrogens on carbonyl oxygen were not observed.

Hindered rotation in trimethylenemethane—Fe(CO)3 complexes

Abstract >13 C NMR spectra have been recorded for trimethylenemethane—Fe(CO) 3 (I) as well as its acetyl (II), 1-hydroxyethyl (III), 1-acetoxyethyl (IV) and ethyl (V) derivatives respectively. Compounds II–IV exhibit 3 distinct 13 CO resonances at room temperature. These signals undergo a reversible broadening and merge into a single sharp signal on warming. δ G G ǂ for Fe(CO) 3 rotation at the coalescence points is 17–18 kcal mol −1 . The rotational barrier is electronic in origin.

Speed liquid chromatographic analysis of organo-iron compounds

Abstract Mixtures which include tricarbonyliron complexes of dienes and dienones plus m-xylene and 2,4-dimethylacetophenone have been separated, and the ketones have been determined quantitatively using reversed phase high speed liquid-liquid partition chromatography.

Degree of phase separation in polyether-polyurethane copolymers with different chemical structures of hard segments

Polyether-polyurethane (PEPU) copolymers based on poly(propylene glycol) (PPO), 4,4′-diphenylmethane diisocyanate (MDI), and different chain extenders [1,5-pentanediol (P), diethylene glycol (D), triethylene glycol (T), and 1,3-bis(N,N′-methyl-N,N′-2-hydroxyethyl)isophthalamide (Bi(M))] were prepared and characterized. The gross properties and the carbonyl absorption patterns in i.r. spectroscopy suggest that the degree of phase separation or hard domain crystallinity decreases in the order of P- > D- > Bi(M)- and T-extended PEPU. D.s.c. results suggest phase-separated systems of PPO/MDI/P, PPO/MDI/D and PPO/MDI/Bi(M), in contrast to a phase-mixed PPO/MDI/T system. The absence of a high temperature melting transition refers to the existence of an amorphous hard domain in the PPO/MDI/Bi(M) system. Chain length, flexibility, and aromatic content of the applied chain extenders control the extent of phase separation of the final products.

Stereospecific generation and quenching of acyclic dienyliron tricarbonyl cations

Abstract ψ- exo - trans -Dienoliron tricarbonyl complexes yield syn , syn -dienyliron tricarbonyl cations and ψ- endo - trans -dienoliron tricarbonyl complexes yield syn , anti -dienyliron tricarbonyl cations with ⩾ 97% stereospecificity in fluorosulfonic acid at −60°C and with lower stereospecificity of 0°C. Aqueous or methanol quenching of these cations at 0°C or below proceeds in the above sense with ⩾97% stereospecificity. However, aqueous quenching of syn , anti cations at 23°C produces up to ca. 30% ψ- exo alcohol which is not the result of acid catalyzed isomerization of ψ- endo alcohol subsequent to quenching. Sodium borohydride reduction of tricarbonyl( cis , trans -4-methyl-3,5-heptadienone)iron(V) gives a single cis -dienol complex which ionizes non-stereospecifically under all conditions. syn , anti -Tricarbonyl(4-methyl-3,5-heptadien-2-yl)iron cation (IV) is configurationally stable in FSO 3 H and H 2 SO 4 for hours at room temperature. The rate of slow isomerization of IV to its syn , syn -isomer is independent of bisulfate ion concentration and is unaccompanied by deuterium incorporation in D 2 SO 4 .

The high pressure liquid chromatographic separation of cis and trans dienone-iron carbonyl complexes and of ψ-endo and ψ-exo dienol-iron carbonyl complexes on 10 m silica

Abstract High Pressure Liquid Chormatography (HPLC) has been used to separate cis and trans dienone-iron carbonyl complexes having different σ and X bonded moieties, and ψ-endo and ψ-exo dienol-iron carbonyl complexes. TLC predicts the appropriate solvent polarity needed and elution order on microparticulate silica columns. Data is reported for methylene chloride and methylene chloride-acetonitrile mobile phases on 10 μm silica.

Head-to-head polymers — XXXII: Toward head-to-head poly(α-methylstyrene): Synthesis of 2,3-dimethyl-2,3-diphenylbutanediol-1,4-ditosylate and 1,4-diphenyl-2,3-dimethylbutadiene-1,3

Abstract2,3-Dimethyl-2,3-diphenylbutanediol-1,4-ditosylate (7) was synthesized starting from 2-phenylpropionic acid (1). The acid chloride was brominated and transformed into methyl 2-phenyl-2-bromo-propionate (4) which was coupled with a zinc/copper couple to dimethyl 2,3-dimethyl-2,3-diphenylsuccinate (5). Reduction with lithium aluminum hydride to 2,3-dimethyl-2,3-diphenylbutanediol-1,4 (6) was followed by tosylation. The tosylate 7 a mixture of the meso and racemic compounds, could be separated into the pure isomers,a m. p. 170 °C andb m. p. 121 °C. The mixture of each individual pure compound, when treated with tetraalkyl-ammonium bromide, did not give the expected 2,3-dimethyl-2,3-diphenyl-1,4-dibromobutane (9) but rather 1,4-diphenyl-2,3-dimethylbutadiene-1,3 (8). The identity of the compound was established by independent unequivocal synthesis, the comparison of spectral characteristics, and mixed melting point.ZusammenfassungAusgehend von 2-Phenylpropionsäure (1) wurde 2,3-Dimethyl-2,3-butandiol-1,4-ditosylat (7) symthetisiert. Das Säurechlorid wurde bromiert und zu Methyl-2-phenyl-2-brom-propionat (4) umgesetzt, das mit Zink/Kupfer zu Dimethyl-2,3-dimethyl-2,3-diphenylsuccinat (5) gekuppelt wurde. Reduktion mitLAH zu 2,3-Dimethyl-2,3-diphenylbutandiol (6) und nachfolgende Tosylierung ergab eine Mischung der meso und racemischen Tosylate7a undb, welche in die reinen Isomere aufgetrennt werden konnten (a Fp. 170 °C undb Fp. 121 °C). Die beiden Verbindungen ergaben bei Behandlung mit Tetraalykylammoniumbromid nicht das erwartete 2,3-Dimethyl-2,3-diphenyl-1,4-dibrombutan (9), sondern 1,4-Diphenyl-2,3-dimethyl-butadien-1,3 (8). Das wurde durch unabhängige Synthese von8 auf anderem Wege, Vergleich der spektroskopischen Eigenschaften und mittels Mischschmelzpunkt nachgewiesen.

Stereochemical leakage mechanisms for tricarbonyl(dienyl)iron cations

Abstract ψ-Endo to ψ-exo leakage during solvolysis of a ψ-endo-dienol—Fe(CO)3 dinitrobenzoate ester does not proceed via a syn, syn-cis-dienyl—Fe(CO)3 cation. The most probable leakage mechanism involves non-stereospecific ionization of the dinitrobenzoate ester. syn,syn-cis-Dienyl—Fe(CO)3 cations are formed from ψ-exo-dienol—Fe(CO)3 complex during chromatography on grade I neutral alumina.