lithium diisopropylamide
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2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Can-Can Bao ◽  
Hui-Zhen Du ◽  
Yan-Long Luo ◽  
Bing-Tao Guan

AbstractAmides are a fundamental and widespread functional group, and are usually considered as poor electrophiles owing to resonance stabilization of the amide bond. Various approaches have been developed to address challenges in amide transformations. Nonetheless, most methods use activated amides, organometallic reagents or transition metal catalysts. Here, we report the direct alkylation of N,N-dialkyl benzamides with methyl sulfides promoted by the readily available base LDA (lithium diisopropylamide). This approach successfully achieves an efficient and selective synthesis of α-sulfenylated ketones without using transition-metal catalysts or organometallic reagents. Preliminary mechanism studies reveal that the deprotonative aroylation of methyl sulfides is promoted by the directed ortho-lithiation of the tertiary benzamide with LDA.


Author(s):  
Roxanne A. Naumann ◽  
Joseph W. Ziller ◽  
Allegra L. Liberman-Martin

The structure of the title compound, C27H46N2, at 93 K has monoclinic (P21/n) symmetry. The title compound was prepared by treatment of 2-(2,6-diisopropylbenzene)-3,3-dimethyl-2-azaspiro[4.5]dec-1-en-2-ium hydrogen dichloride with two equivalents of lithium diethylamide. Characterization of the title compound by single-crystal X-ray diffraction and 1H and 13C NMR spectroscopy is presented. Formation of the diethylamine adduct of the cyclic(alkyl)(amino)carbene (CAAC) was unexpected, as deprotonation using lithium diisopropylamide results in free CAAC formation.


2021 ◽  
Vol 25 (4) ◽  
pp. 988-1000
Author(s):  
Marta Alonso ◽  
Maria Cruz Garcia ◽  
Christopher McKay ◽  
Lee R. Thorp ◽  
Michael Webb ◽  
...  

2021 ◽  
Author(s):  
Hiroaki Shimomoto ◽  
Shogo Tsunematsu ◽  
Tomomichi Itoh ◽  
Eiji Ihara

The reactivities of poly(alkoxycarbonylmethylene)s under basic conditions are described. The reactions of poly(ethoxycarbonylmethylene) (polyEDA’) and poly(benzyloxycarbonylmethylene) (polyBDA’) with a mixture of lithium diisopropylamide and trimethylsilyl chloride transformed a part of...


Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5920
Author(s):  
Anastasiya V. Igushkina ◽  
Alexander A. Golovanov ◽  
Irina A. Boyarskaya ◽  
Ilya E. Kolesnikov ◽  
Aleksander V. Vasilyev

Reaction of linear conjugated enynones, 1,5-diarylpent-2-en-4-yn-1-ones, with malononitrile in the presence of lithium diisopropylamide LDA, as a base, in THF at room temperature for 3–7 h resulted in the formation of the product of dimerization, multisubstituted polyfunctional cyclohexanes, 4-aryl-2,6-bis(arylethynyl)-3-(aryloxomethyl)-4-hydroxycyclohexane-1,1-dicarbonitriles, in yields up to 60%. Varying the reaction conditions by decreasing time and temperature and changing the ratio of starting compounds (enynone and malononitrile) allowed isolating some intermediate compounds, which confirmed a plausible reaction mechanism. The relative stability of possible stereoisomers of such cyclohexanes was estimated by quantum chemical calculations (DFT method). The obtained cyclohexanes were found to possess photoluminescent properties.


Synlett ◽  
2020 ◽  
Vol 31 (19) ◽  
pp. 1913-1918
Author(s):  
Kentaro Okano ◽  
Yoshiki Yamane ◽  
Aiichiro Nagaki ◽  
Atsunori Mori

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.


2018 ◽  
Vol 20 (22) ◽  
pp. 7177-7181 ◽  
Author(s):  
Xiang-Yu Zhang ◽  
Lei Zheng ◽  
Bing-Tao Guan

2017 ◽  
Vol 82 (9) ◽  
pp. 4513-4532 ◽  
Author(s):  
Russell F. Algera ◽  
Lekha Gupta ◽  
Alexander C. Hoepker ◽  
Jun Liang ◽  
Yun Ma ◽  
...  

SynOpen ◽  
2017 ◽  
Vol 01 (01) ◽  
pp. 0084-0090 ◽  
Author(s):  
Pavel Nosik ◽  
Oleksiy Artamonov ◽  
Sergey Ryabukhin ◽  
Oleksandr Grygorenko

An approach to isomeric 1,1-disubstituted pyrazolylcyclopropanes that relies on lithium diisopropylamide (LDA) mediated bis-alkylation­ of the corresponding pyrazolylacetonitriles is developed. The building blocks obtained can be considered as lead-like bioisosteres of arylpyrazole and pyrazolecarboxamide moieties and are thus useful for early drug discovery projects.


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