The Chemistry of 5-Oxodihydroisoxazoles. X. Butyllithium and Lithium Diisopropylamide Promoted Rearrangements of 3-Unsubstituted Isoxazol-5(2H)-ones

1994 ◽  
Vol 47 (9) ◽  
pp. 1673 ◽  
Author(s):  
RH Prager ◽  
P Razzino
Keyword(s):  
Reaction Pathway ◽  
Alkyl Halides ◽  
Lithium Diisopropylamide ◽  
Methyl Phenyl

The reaction pathway of 3-unsubstituted isoxazol-5(2H)-ones with bases, proposed by Woodman1-3 to proceed via four intermediates to azetidine-2,4-diones, has been confirmed by the isolation of products unequivocally derived from each of the intermediates. Isoxazol-5(2H)-ones substituted on nitrogen by methyl, phenyl, quinolin-2-yl and vinyl groups have been studied. The azetidine-2,4-diones have only been isolated when the intermediate enolate has been alkylated , but only reactive alkyl halides lead to useful syntheses.

scholarly journals Substitution α to the Nitrogen in Dibenzylamine via Carbanion Intermediates

1973 ◽  
Vol 51 (7) ◽  
pp. 1109-1115 ◽  
Author(s):  
Robert R. Fraser ◽  
Guy Boussard ◽  
I. Dan Postescu ◽  
Josephine J. Whiting; ◽  
Yuk Y. Wigfield
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Compounds ◽  
Alkyl Halides ◽  
Lithium Diisopropylamide ◽  
Derivatives Of

A method has been developed for introducing a variety of substituents into the position α to the nitrogen atom of dibenzylamine. Treatment of either the nitroso or the benzoyl derivative of dibenzylamine with lithium diisopropylamide generates a carbanion which reacts with alkyl halides or carbonyl compounds producing α-substitution products in yields of 66–99%. The method also gives good yields of derivatives of N-phenyl-N′-nitroso-piperazine. Attempts to form the carbanion of N-benzoylpiperidine failed.

scholarly journals Trapping of Transient Thienyllithiums Generated by Deprotonation of 2,3- or 2,5-Dibromothiophene in a Flow Microreactor

Synlett ◽  
2020 ◽  
Vol 31 (19) ◽  
pp. 1913-1918
Author(s):  
Kentaro Okano ◽  
Yoshiki Yamane ◽  
Aiichiro Nagaki ◽  
Atsunori Mori
Keyword(s):  
Carbonyl Compounds ◽  
Reaction Pathway ◽  
Reaction System ◽  
Lithium Diisopropylamide ◽  
Flow Microreactor

AbstractSelective trapping of (4,5-dibromo-2-thienyl)lithium, known to undergo halogen dance, was achieved in a flow microreactor. This transient thienyllithium, generated by mixing 2,3-dibromothiophene and lithium diisopropylamide at –78 °C for 1.6 seconds, reacted with benzaldehyde. The reaction system is also applicable to other carbonyl compounds to afford the corresponding adducts in good yields. Moreover, the established conditions permit the conversion of 2,5-dibromothiophene into a mixture of the two constitutional isomers. The contrasting results are discussed on the basis of the reaction pathway.

Metallation of N-Substituted β-Lactams. A Method for the Introduction of 3-Substituents into β-Lactams

1972 ◽  
Vol 50 (19) ◽  
pp. 3196-3201 ◽  
Author(s):  
T. Durst ◽  
M. J. LeBelle
Keyword(s):  
Good Yield ◽  
Alkyl Halides ◽  
Lithium Diisopropylamide

N-Alkyl and N-aryl β-lactams yield lithio carbanions upon reaction with lithium diisopropylamide in tetrahydrofuran at −78°. These lithio salts react with a variety of electrophiles (e.g. ketones, esters, reactive alkyl halides) to give the 3-substituted derivatives in fair to good yield. The procedure is useful for the preparation of rather complex 3-substituted β-lactams from readily available simple derivatives.

Vitamin B12-based elimination of alkyl halides

2020 ◽  
Author(s):  
Julian West ◽  
Alexandros S Pollatos ◽  
Radha Bam
Keyword(s):  
Vitamin B12 ◽  
Alkyl Halides

Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

Fe-Catalyzed Conjunctive Cross-Couplings of Unactivated Alkenes with Grignard Reagents

2020 ◽  
Author(s):  
Lei Liu ◽  
Wes Lee ◽  
Cassandra R. Youshaw ◽  
Mingbin Yuan ◽  
Michael B. Geherty ◽  
...  
Keyword(s):  
Functional Groups ◽  
Cross Coupling ◽  
Alkyl Halides ◽  
Grignard Reagents ◽  
Turnover Frequency ◽  
Diverse Range ◽  
Cascade Cyclization ◽  
Radical Cascade

The first iron-catalyzed three-component cross-coupling of unactivated olefins with alkyl halides and Grignard reagents is reported. The reaction operates under fast turnover frequency and tolerates a diverse range of sp2-hybridized nucleophiles, alkyl halides, and unactivated olefins bearing diverse functional groups to yield the desired 1,2-alkylarylated products with high regiocontrol. Further, we demonstrate that this protocol is amenable for the synthesis of new (hetero)carbocycles including tetrahydrofurans and pyrrolidines via a three-component radical cascade cyclization/arylation that forges three new C-C bonds.

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