ChemInform Abstract: Pyridinium Ylides in Organic Synthesis. Part 4. Pyridinium Ylides in Nucleophilic Addition-Elimination (AdN-E) Reactions

ChemInform ◽  
2010 ◽  
Vol 29 (38) ◽  
pp. no-no
Author(s):  
V. P. LITVINOV ◽  
A. M. SHESTOPALOV
Keyword(s):  
Organic Synthesis ◽  
Nucleophilic Addition ◽  
Pyridinium Ylides

scholarly journals Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling of Aryl Chlorobenzoates with Alkyl Grignard Reagents

Molecules ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 230 ◽  
Author(s):  
Elwira Bisz ◽  
Michal Szostak
Keyword(s):  
Organic Synthesis ◽  
Nucleophilic Addition ◽  
Functional Group ◽  
High Selectivity ◽  
Cross Coupling ◽  
Environmentally Benign ◽  
Grignard Reagents ◽  
High Importance ◽  
Iron Salts ◽  
The Cross

Aryl benzoates are compounds of high importance in organic synthesis. Herein, we report the iron-catalyzed C(sp2)–C(sp3) Kumada cross-coupling of aryl chlorobenzoates with alkyl Grignard reagents. The method is characterized by the use of environmentally benign and sustainable iron salts for cross-coupling in the catalytic system, employing benign urea ligands in the place of reprotoxic NMP (NMP = N-methyl-2-pyrrolidone). It is notable that high selectivity for the cross-coupling is achieved in the presence of hydrolytically-labile and prone to nucleophilic addition phenolic ester C(acyl)–O bonds. The reaction provides access to alkyl-functionalized aryl benzoates. The examination of various O-coordinating ligands demonstrates the high activity of urea ligands in promoting the cross-coupling versus nucleophilic addition to the ester C(acyl)–O bond. The method showcases the functional group tolerance of iron-catalyzed Kumada cross-couplings.

scholarly journals Photocatalytic α-Alkylation of Amines with Alkyl Halides

2020 ◽  
Author(s):  
Lingying Leng ◽  
Joseph Ready
Keyword(s):  
Organic Synthesis ◽  
Nucleophilic Addition ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Organometallic Reagents ◽  
Dehydrogenative Coupling ◽  
Alkyl Bromides ◽  
Alternative Approach ◽  
Traditionally Prepared ◽  
Carbon Centered Radical

a-Branched amines represent essential building blocks for organic synthesis. They are traditionally prepared through nucleophilic addition to imines. These methods often require highly reactive organometallic reagents and proceed under rigorous air- and moisture-free conditions. Here we describe an alternative approach that involves a net dehydrogenative coupling between alkyl bromides and amines. Mechanistically, the reaction likely involves photocatalytic generation of an a-amino radical and a stabilized carbon-centered radical (allyl, benzyl, a-carbonyl) followed by radical recombination. This approach offers a mild, atom-economical, redox neutral synthesis of a-branched amines that shows broad scope and avoids pre-metalated reagents.

scholarly journals Mechanochemical synthesis of magnesium-based carbon nucleophiles in air and their use in organic synthesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rina Takahashi ◽  
Anqi Hu ◽  
Pan Gao ◽  
Yunpeng Gao ◽  
Yadong Pang ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Mechanochemical Synthesis ◽  
Nucleophilic Addition ◽  
Reaction Times ◽  
Grignard Reagents ◽  
Coupling Reactions ◽  
One Pot ◽  
Carbon Nucleophiles ◽  
Cross Coupling Reactions ◽  
Solvent Free Conditions

AbstractSince the discovery of Grignard reagents in 1900, the nucleophilic addition of magnesium-based carbon nucleophiles to various electrophiles has become one of the most powerful, versatile, and well-established methods for the formation of carbon−carbon bonds in organic synthesis. Grignard reagents are typically prepared via reactions between organic halides and magnesium metal in a solvent. However, this method usually requires the use of dry organic solvents, long reaction times, strict control of the reaction temperature, and inert-gas-line techniques. Despite the utility of Grignard reagents, these requirements still represent major drawbacks from both an environmental and an economic perspective, and often cause reproducibility problems. Here, we report the general mechanochemical synthesis of magnesium-based carbon nucleophiles (Grignard reagents in paste form) in air using a ball milling technique. These nucleophiles can be used directly for one-pot nucleophilic addition reactions with various electrophiles and nickel-catalyzed cross-coupling reactions under solvent-free conditions.

Thioesterification and Selenoesterification of Amides via Selective N–C Cleavage at Room Temperature: N–C(O) to S/Se–C(O) Interconversion

Synthesis ◽  
2020 ◽  
Vol 52 (07) ◽  
pp. 1060-1066 ◽  
Author(s):  
Md. Mahbubur Rahman ◽  
Guangchen Li ◽  
Michal Szostak
Keyword(s):  
Transition Metals ◽  
Organic Synthesis ◽  
Ground State ◽  
Nucleophilic Addition ◽  
Room Temperature ◽  
Bond Cleavage ◽  
Tetrahedral Intermediate

The direct nucleophilic addition to amides represents an attractive methodology in organic synthesis that tackles amidic resonance by ground-state destabilization. This approach has been recently accomplished with carbon, nitrogen and oxygen nucleophiles. Herein, we report an exceedingly mild method for the direct thioesterification and selenoesterification of amides by selective N–C(O) bond cleavage in the absence of transition metals. Acyclic amides undergo N–C(O) to S/Se–C(O) interconversion to give the corresponding thioesters and selenoesters in excellent yields at room temperature via a tetrahedral intermediate pathway (cf. an acyl metal).

Sign in / Sign up

Export Citation Format

Share Document