magnesium exchange
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Synthesis ◽  
2022 ◽  
Author(s):  
Yuya Okui ◽  
Yuto Yasuda ◽  
Atsunori Mori ◽  
Kentaro Okano

A total synthesis of lamellarins U and A3 is described. The synthesis features interruption of a halogen dance reaction of a metalated α,β-dibromopyrrole. The pyrrolylmagnesium reagent, generated by deprotonative metalation using (TMP)MgCl·LiCl (TMP: 2,2,6,6-tetramethylpiperidide) as base, was transmetalated to the corresponding organozinc species without causing the halogen dance reaction, which underwent a Negishi coupling to incorporate an aryl group onto the pyrrole ring. The arylated α,β-dibromopyrrole was then converted into lamellarins U and A3 through an α-selective halogen–magnesium exchange followed by carboxylation and subsequent palladium-mediated cyclization. The late-stage introduction of another aryl group was performed using a Kosugi–Migita–Stille coupling to provide lamellarins U and A3.


Synthesis ◽  
2021 ◽  
Author(s):  
Alexandre Desaintjean ◽  
Fanny Danton ◽  
Paul Knochel

A wide range of polyfunctionalized di(hetero)aryl- and dialkenyl-magnesium reagents were prepared in toluene within 10 to 120 min between −78 °C and 25 °C via an I/Mg- or Br/Mg-exchange reaction using reagents of the general formula R2Mg (R = sBu, Mes). Highly sensitive functional groups, such as a triazene or a nitro group, were tolerated in these exchange reactions, enabling the synthesis of various functionalized (hetero)arenes and alkenes derivatives after quenching with several electrophiles including allyl bromides, acyl chlorides, aldehydes, ketones, and aryl iodides.


2021 ◽  
Vol 17 ◽  
pp. 1352-1359
Author(s):  
Tsutomu Kimura ◽  
Koto Sekiguchi ◽  
Akane Ando ◽  
Aki Imafuji

A series of 1-heteroatom-substituted vinyl p-tolyl sulfoxides were prepared and treated with organometallic reagents to evaluate which combination of sulfoxides and organometallic reagents yielded alkynes the most efficiently. The use of 1-chlorovinyl p-tolyl sulfoxide and isopropylmagnesium chloride was optimal for this purpose. A variety of 1-chlorovinyl p-tolyl sulfoxides were prepared from carbonyl compounds and chloromethyl p-tolyl sulfoxide and were converted into alkynes via the sulfoxide/magnesium exchange reaction and subsequent Fritsch–Buttenberg–Wiechell (FBW) rearrangement of the resulting magnesium alkylidene carbenoids. The mechanism of the FBW rearrangement of magnesium alkylidene carbenoids was studied by using 13C-labeled sulfoxides and by using DFT calculations.


Author(s):  
Alexandre Desaintjean ◽  
Tobias Haupt ◽  
Leonie J. Bole ◽  
Neil R. Judge ◽  
Eva Hevia ◽  
...  

2018 ◽  
Vol 25 (11) ◽  
pp. 2695-2703 ◽  
Author(s):  
Dorothée S. Ziegler ◽  
Baosheng Wei ◽  
Paul Knochel

2018 ◽  
Vol 3 (4) ◽  
pp. 85-100
Author(s):  
R. A. Bekker ◽  
Yu. V. Bykov

The use of boron preparations (borax and boric acid) in medicine began long before their isolation in pure form. The mineral water of  boron-containing sources has been historically used to treat skin  diseases, to wash eyes, to disinfect wounds, etc. Also, what is of  interest in the context of this article, boron-containing waters were  used as calming, anti- anxiety, anticonvulsant and sleep-promoting  remedy. In 1777, boric acid was first isolated from the mineral water of a healing spring source in Florence. Historically, first name  of this compound was sal sedativum (“soothing salt”). However, the  discovery of boron toxicity led to the cessation of its internal use. In  recent decades, it has been found that boron is a microelement  necessary for many metabolic processes in the body. It affects  memory, cognitive functions, anxiety level, sleep, mood, regulates  calcium and magnesium exchange, metabolism of vitamin D and sex  steroids. It has been shown that some cases of treatment  resistance to standard therapy, for example in epilepsy, anxiety and depression, are related to boron deficiency. In this regard,  interest in the use of boron preparations in psychiatry and neurology, but in much smaller doses and on new scientific grounds, flared up again.


Synthesis ◽  
2018 ◽  
Vol 50 (18) ◽  
pp. 3589-3602
Author(s):  
Anne Boussonnière ◽  
Anne-Sophie Castanet ◽  
Hélène Guyon

Organomagnesium reagents are among the most important reagents in organic chemistry because of their great utility in forming carbon–carbon bonds. Although most enantioselective reactions using these organometallics involve transmetalation, the past decade has witnessed impressive advances in direct chiral-ligand-mediated reactions of organomagnesiums­. This short review presents an overview of these achievements in enantioselective nucleophilic additions and substitutions.1 Introduction2 Enantioselective Nucleophilic Additions2.1 Addition to C=O Bonds2.2 Addition to C=N Bonds2.3 Addition to C=C Bonds3 Enantioselective Substitution Reactions3.1 Sulfoxide–Magnesium Exchange3.2 Desymmetrization via Anhydride Opening3.3 Asymmetric Allylic Alkylation (AAA)4 Conclusion


2018 ◽  
Vol 68 (1) ◽  
pp. 40-49
Author(s):  
Vesna Rodić ◽  
Marica Bogosavljević ◽  
Saša Brzić ◽  
Bojana Fidanovski

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