The halogen-metal interconversion of aryl bromides and n-butyllithium in non-polar solvents

Trepka, William J.; Sonnenfeld, R. J.

doi:10.1016/s0022-328x(00)81121-3

Cited by 26 publications

(3 citation statements)

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“…The first step of the procedure is the synthesis of the tri- and tetracarbanionic initiators based on the halogen−lithium exchange reaction. As described previously, − the tetrabromo compound ( 1 ) is modified to give the corresponding tetraalkyllithium agent ( 2 ), and importantly for this synthesis, lithium 2-methoxyethoxide ( 3 ) was utilized to solubilize the polyalkyllithium species due to the σ/μ complex formed between the lithiated species ( 2 and 3 ) . These complexes give stable species and enough steric bulk to prevent aggregation of the polylithiated initiators.…”

Section: Resultsmentioning

confidence: 99%

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

et al. 2005

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We describe the preparation and the surface properties of monolayers of a new set of (PBb-PEO)4 amphiphilic four-arm star block copolymers. A divergent anionic polymerization method yielded copolymers with well-defined molecular weights, block volume fractions, and architecture. Initially, triand tetracarbanionic initiators were used to initiate the polymerization of butadiene followed by endcapping of living chains with ethylene oxide. The tri-and tetrafunctionalities of the resulting hydroxylterminated star polydienes were confirmed by 1 H NMR spectroscopy. The four-arm star polymeric alcohols were then titrated with diphenylmethylpotassium to yield the analogous potassium alkoxides. The resulting macroinitiators were used to polymerize corona blocks of ethylene oxide. Different samples of well-defined (PB-b-PEO)4 amphiphilic star block copolymers exhibiting narrow molar mass distribution were prepared with poly(ethylene oxide) over a range of volume fractions. Isotherm experiments at the air/water interface showed the following three characteristic regions: a compact brush region, a pseudoplateau at a pressure of ca. 10 mN/m, and a pancake region where the observed surface area depended on the amount of PEO present. The elasticity properties of the monolayer were examined by repetative compression/expansion cycles and resulted in reproducible hysteresis at different pressures. The monolayers were also transferred as Langmuir-Blodgett films on mica at various surface pressures and analyzed by atomic force microscopy (AFM), demonstrating different morphologies from analogous (PS-b-PEO) 4 star copolymers.

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Section: Resultsmentioning

confidence: 99%

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

et al. 2005

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“…10 Anisoyllithium was prepared by the methods of Berree et al 40 and used as a 0.43 M ethereal solution, while (p-bromophenyl)lithium was prepared by the methods of Trepka and Sonnenfeld used as a 0.37 M ethereal solution. 41 BOP was prepared by the methods of Castro. 42 Thiopyridyl chloroformate was used as a 0.19 M solution in CH2Cl2 and prepared according the methods of Corey.…”

Section: Methodsmentioning

confidence: 99%

Asymmetric Synthesis and Pharmacology of Methylphenidate and Its Para-Substituted Derivatives

et al. 1998

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We report the first asymmetric synthesis of the individual enantiomers of methylphenidate (1). From d-pipecolic acid, the (2R,2'R) and (2S,2'R) enantiomers of 1 were obtained in > 99% optical purity while the (2S,2'S) and (2R,2'S) enantiomers of 1 were derived from l-pipecolic acid in 96% optical purity. The versatility of this methodology is demonstrated with the synthesis of the (2R,2'R) and (2S,2'S) enantiomers of p-bromo and p-methoxy derivatives in similar yields and enantiomeric purities. Comparative neurochemical assessments of these synthesized enantiomers at purported dopamine, norepinephrine, and serotonin uptake sites along with locomotor activity studies in rats are also reported.

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“…Similar yields of the corresponding 4-arylcubyl iodides were achieved when p -biphenyllithium (→ 6 ) and 2-naphthyllithium (→ 7 ) were employed. Use of the doubly lithiated aromatic 1,4-dilithiobenzene, prepared by halogen−metal exchange between p -dibromobenzene and excess t -BuLi, gave p -bis(4-iodocubyl)benzene ( 8 ) in 70% isolated yield. Similarly, reaction of diiodocubane with 1,3-dilithiobenzene 13 gave the meta isomer 9 .…”

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confidence: 99%

Building with Cubane-1,4-diyl. Synthesis of Aryl-Substituted Cubanes, p-[n]Cubyls, and Cubane-Separated Bis(arenes)¹

et al. 1999

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On treatment with an organolithium 1,4-diiodocubane generates cubane-1,4-diyl, a highly reactive species, shown here to be a versatile precursor to numerous aryl substituted cubanes, available now for the first time in high yield. The diyl is demonstrated to provide a good route to bicubyl and its derivatives. A kind of “living polymerization” of the diyl is developed to give the p-[n]cubyls. These oligomers are rigid rods made up of cubanes linked together at the 1 and 4 positions, each cubane adding ∼4.15 Å to the length. The properties of these rods, some more than 15 Å long, are discussed, as are methods for modifying their solubility. X-ray crystallographic analyses of some of these compounds are presented, with emphasis on packing parameters.

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The halogen-metal interconversion of aryl bromides and n-butyllithium in non-polar solvents

Cited by 26 publications

References 10 publications

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

Asymmetric Synthesis and Pharmacology of Methylphenidate and Its Para-Substituted Derivatives

Building with Cubane-1,4-diyl. Synthesis of Aryl-Substituted Cubanes, p-[n]Cubyls, and Cubane-Separated Bis(arenes)¹

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The halogen-metal interconversion of aryl bromides and n-butyllithium in non-polar solvents

Cited by 26 publications

References 10 publications

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

Interfacial Behavior of Anionically Synthesized Amphiphilic Star Block Copolymers Based on Polybutadiene and Poly(ethylene oxide) at the Air/Water Interface

Asymmetric Synthesis and Pharmacology of Methylphenidate and Its Para-Substituted Derivatives

Building with Cubane-1,4-diyl. Synthesis of Aryl-Substituted Cubanes, p-[n]Cubyls, and Cubane-Separated Bis(arenes)1

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Building with Cubane-1,4-diyl. Synthesis of Aryl-Substituted Cubanes, p-[n]Cubyls, and Cubane-Separated Bis(arenes)¹