Y-Conjugated dianions: a comparison between the 1,1-dibenzylethylene and diphenylacetone-derived dianions

Wilhelm, Dieter; Clark, Timothy; Schleyer, Paul von Ragué

doi:10.1039/p29840000915

Cited by 9 publications

(9 citation statements)

References 6 publications

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“…1986, 24, 145. (17) In compounds 3,5,7,9,11,12, and 13 the letters a-g have the same meaning. (20) Goodridge, R. J.; Hambley, T. W.; Ridley, D. D. Aust.…”

Section: Resultsmentioning

confidence: 99%

Ring-chain tautomerism in 1,3-oxazines

Fülöp¹,

Pihlaja²,

Mattinen³

et al. 1987

J. Org. Chem.

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of unlabeled 2. The quenching factor, 1.3027, was used to normalize the counts of samples of 2 from rearrangement.Calculations of HIE were made as described earlier.30 Irradiation of 4-Methoxyphenyl Acetate (1), 2-Acetyl-4methoxyphenol (2), and 4-Methoxyphenol for Spectroscopic Measurements. Solutions of these compounds were irradiated in the Rayonet reactor as described above. Samples (3 mL) were withdrawn at timed intervals for recording absorbance at 356 nm. Neither 1 nor 4-methoxyphenol absorb in this region. Data for irradiations of 1 in the absence and presence of propanethiol are given in Figure 1. They show the formation and slow decomposition of 2 in the absence of propanethiol and the formation and stability of 2 in its presence. Data for the prolonged irradiation of 2 alone and in the presence of propanethiol, 2,3-butanedione, and 4-methoxyphenol are given in Figure 2. Included in Figure 2 are data for the irradiation of 4-methoxyphenol alone. This compound was itself decomposed by prolonged irradiation at 300 nm, and the unknown product(s) of decomposition absorbed weakly at 356 nm.The following absorbance data (X^[nm], t) are pertinent: 1

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“…1986, 24, 145. (17) In compounds 3,5,7,9,11,12, and 13 the letters a-g have the same meaning. (20) Goodridge, R. J.; Hambley, T. W.; Ridley, D. D. Aust.…”

Section: Resultsmentioning

confidence: 99%

Ring-chain tautomerism in 1,3-oxazines

Fülöp¹,

Pihlaja²,

Mattinen³

et al. 1987

J. Org. Chem.

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“…Elemental analyses were carried out by Desert Analytics. The preparations of Cp*(TMM)TaMe 2 , Li 2 (TBM)(TMEDA) 2 , Li 2 ( t -BuTBM)(TMEDA) 2 , and Li 2 (TMM)(TMEDA) 2 , are available in the literature. MAO was purchased from AKZO Chemicals (toluene, 6.4 wt % Al, type 4).…”

Section: Methodsmentioning

confidence: 99%

Binding Preferences of the Tribenzylidenemethane Ligand in High-Oxidation-State Tantalum Complexes

et al. 1998

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Reaction of Li 2 (TBM)(TMEDA) 2 (TBM ) tribenzylidenemethane) with TaMe 3 Cl 2 gives (TBM)-TaMe 3 (1) in 44% yield. Structural characterization of the (tert-Bu-TBM)TaMe 3 derivative 2 shows an eclipsed orientation of the TaMe 3 tripod relative to the inner core of the TBM ligand. Treatment of (TBM)TaMe 3 with ZnCl 2 cleanly replaces one methyl ligand for chloride to give (TBM)TaMe 2 Cl (3) which is a versatile precursor to (TBM)Ta-based complexes. Addition of LiNPh 2 to 3 gives (TBM)TaMe 2 (NPh 2 ) (4). Structural characterization reveals that both 3 and 4 have eclipsed frameworks. Metallocene-mimics are accessible by reacting LiCp (Cp ) C 5 H 5 ), LiCp* (Cp* ) C 5 Me 5 ), LiCp′ (Cp′ ) C 5 H 4 Me), or LiFlu (Flu ) fluorenyl) with 3 to give Cp(TBM)TaMe 2 (5), Cp*(TBM)TaMe 2 (6), Cp′(TBM)TaMe 2 (7), and Flu(TBM)TaMe 2 (8), respectively. The solid-state structures of 5, 7, and 8 display gross molecular geometries similar to those of group 4 metallocenes. Complex 3 reacts with tris(pyrazolylborate) or bis(pyrazolylborate) salts. Thus, [HB-(pz) 3 ](TBM)TaMe 2 ( 9), [HB(3,5-Me 2 -1-pz) 3 ](TBM)TaMe 2 (10), and [H 2 B(pz) 2 ](TBM)TaMe 2 (11) are obtained from Na[HB(pz) 3 ], K[HB(3,5-Me 2 -1-pz) 3 ], and K[H 2 B(pz) 2 ], respectively. Structural characterization of 9, 10, and 11 shows that TBM can adopt a continuum of bonding modes, from η 4 to η 2 , depending on the steric hindrance around the metal center. The TMM ligand participates in hydrogenation and insertion reactions, indicating that TMM is a weak ancillary ligand. Combining 6, 7, or 8 with MAO results in short-lived ethylene polymerization catalysts. Finally, an electronic description of the model complex (TMM)TaMe 3 is developed to account for the eclipsed molecular structures of 1-4. A comparison against the orbital description of staggered (TMM)Fe(CO) 3 is also made.

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“…The reaction of the dianion of 1,3-diphenylacetone 20 [24] with benzophenone and trimethylchlorosilane afforded the silyl enol ether PhCHϭC(OSiMe 3 )CH(Ph)ϪC(OSiMe 3 )Ph 2 (21) in 83% yield. In contrast, complex mixtures were obtained when diethylmalonic dichloride and phthalic dichloride were used.…”

Section: Scheme 6 Synthesis Of Heterospirocyclic Isobenzofuranones 1mentioning

confidence: 99%

“…The main Scheme 7. Reaction of the dianion of acetanilide with benzophenone and phthalic dichloride product (66%) was N-phenylphthalimide (24), which was presumably formed by a transamination process via intermediates C and D.…”

Section: Scheme 6 Synthesis Of Heterospirocyclic Isobenzofuranones 1mentioning

confidence: 99%

Regioselective Synthesis of Heterospirocyclic Isobenzofuranones and Medium-Sized Lactones by Multiple Anion Capture Reactions of 1,3-Dianions

2001

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The multicomponent reaction of 1,3-dianions with ketones and oxalic acid dichloride or diethylmalonic dichloride afforded six-to eight-membered lactones. Treatment of the dianion of 3-acetylindole with benzophenone and diethylmaDomino and multi-component reactions have found widespread applications in organic synthesis. [1] Multiple anion capture reactions involve attack of a carbanion on a relais species to form an intermediate which is subsequently reacted with an electrophile. Recent examples include the reaction of carbon nucleophiles with allenes and subsequent cyclization with acrylates, [2] and reactions involving isocyanates [3] or allenyl isothiocyanates as the relais species. [4] Multiple anion capture reactions involving nitriles as the relais species have been observed in the reaction of bislithiated 2,3-methylbutadiene with benzonitrile, [5] and in the 1,4-addition of nitriles to (butadiene)zirconocene. [6] In the course of our program [7] directed at the development of cyclization reactions of dianions [8] and dianion equivalents with dielectrophiles, we have recently studied nitriles as relais species in reactions of 1,3-dianions [9aϪ9c] and dilithiated allenes. [9d] We wish to report full details of our studies related to multiple anion capture reactions of 1,3-dianions with ketones and carboxylic acid dichlorides. [10] These reactions provide an efficient access to medium-sized lactones and novel heterospirocyclic isobenzofuranones. [11Ϫ13] Results and Discussion Synthesis of Lactones and Silyl EthersChlorosilanes were used in our first experiments aimed at demonstrating the concept of multiple anion capture reactions of dianions with ketone relais species. The dianion [14] of 1,1-diphenylacetone 1 was generated by treatment of 1 with potassium hydride and nBuLi. The dianion was condensed in situ with one equivalent of benzophenone 2a to give the dianionic intermediate A by regioselective attack of the terminal carbon atom of the dianion at the carbonyl group. Owing to steric and electronic reasons (delocaliz- [a] 1511 lonic dichloride resulted in the formation of a cyclic 1,3,5-triketooctene. The reaction of 1,3-dianions with ketones and phthalic dichloride resulted in the formation of heterospirocyclic isobenzofuranones rather than of medium-sized rings.ation of the negative charge through the phenyl rings), the carbon attached to the phenyl groups is less nucleophilic than the terminal carbon of the dianion. Subsequent addition of Me 3 SiCl gave the open-chain silyl ethers 3a and 3b in high yields (Scheme 1). Reaction of intermediate A with dichloro-diphenylsilane afforded the 1,3,2-dioxasilinane 3c in 76% yield. Scheme 1. Reaction of the dianion of 1,1-diphenylacetone with benzophenone and chlorosilanes Three-component cyclizations of dianions with ketones and dicarboxylic acid dichlorides were studied next. These reactions can, in principle, result in the formation of different regioisomeric cyclization products, as well as macrocyclic or polymeric products. In fact, we have found that...

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Y-Conjugated dianions: a comparison between the 1,1-dibenzylethylene and diphenylacetone-derived dianions

Cited by 9 publications

References 6 publications

Ring-chain tautomerism in 1,3-oxazines

Ring-chain tautomerism in 1,3-oxazines

Binding Preferences of the Tribenzylidenemethane Ligand in High-Oxidation-State Tantalum Complexes

Regioselective Synthesis of Heterospirocyclic Isobenzofuranones and Medium-Sized Lactones by Multiple Anion Capture Reactions of 1,3-Dianions

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