scholarly journals Organometallic reagents primed for peptide modification

2021 ◽  
Vol 1 (4) ◽  
pp. 758-760
Author(s):  
Cecile Elgindy ◽  
Lara R. Malins
Keyword(s):  
Organometallic Reagents ◽  
Peptide Modification

Enantioselective Multi-Component Cyclopropane Synthesis Enabled by Cu-Catalyzed Cyclopropene Carbometallation with Organoboron Reagent

2018 ◽  
Author(s):  
Zhanyu Li ◽  
Mengru Zhang ◽  
Yu Zhang ◽  
Shuang Liu ◽  
Jinbo Zhao ◽  
...  
Keyword(s):  
Carbon Source ◽  
Stereoselective Synthesis ◽  
Organometallic Reagents ◽  
Preliminary Results ◽  
Quaternary Center ◽  
Chiral Centers ◽  
Substituted Cyclopropanes ◽  
Proof Of Principle

Deployment of organoboron in lieu of the strongly basic <br>organometallic reagents as carbon source in Cu-catalyzed <br>cyclopropene carbometallation opens unprecedented three-<br>component reactivity for stereoselective synthesis of poly-substituted cyclopropanes. A proof-of-principle demonstration of this novel carbometallation strategy is presented herein for a highly convergent access to poly-substituted aminocyclopropane framework via <br>carboamination. Preliminary results on asymmetric desymmetrization with commercial bisphosphine ligands attained high levels of enantioselection, offering a straightforward access to enantioenriched aminocyclopropanes bearing all-three chiral centers, including an all-carbon quaternary center. This strategy may underpin a host of novel synthetic protocols for poly-substituted cyclopropanes. <br>

scholarly journals The Direct Carbamoylation of Organometallic Reagents with 1,2,3-Benzotriazole -1-carboxamides

1999 ◽  
Vol 23 (3) ◽  
pp. 230-231
Author(s):  
Alan R. Katritzky ◽  
Daphne A. Monteux ◽  
Dmytro O. Tymoshenko ◽  
Sergei A. Belyakov
Keyword(s):  
Organometallic Reagents

Various (hetero) aromatic amides are synthesized efficiently by the carbamoylation of organometallic reagents.

scholarly journals Developing a Methodology for Catalytic Asymmetric Crotylation of Aldehydes

Synlett ◽  
2021 ◽  
Author(s):  
Andrei V. Malkov ◽  
Aleksandr E. Rubtsov
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Chiral Auxiliaries ◽  
Organometallic Reagents ◽  
Total Syntheses ◽  
Base Catalysts ◽  
Homoallylic Alcohols ◽  
Stereogenic Centers ◽  
Long Time ◽  
Lewis Base Catalysts

AbstractAsymmetric crotylation has firmly earned a place among the set of valuable synthetic tools for stereoselective construction of carbon skeletons. For a long time the field was heavily dominated by reagents bearing stoichiometric chiral auxiliaries, but now catalytic methods are gradually taking center stage, and the area continues to develop rapidly. This account focuses primarily on preformed organometallic reagents based on silicon and, to some extent, boron. It narrates our endeavors to design new and efficient chiral Lewis base catalysts for the asymmetric addition of crotyl(trichloro)silanes to aldehydes. It also covers the development of a novel protocol for kinetic resolution of racemic secondary allylboronates to give enantio- and diastereomerically enriched linear homoallylic alcohols. As a separate topic, cross-crotylation of aldehydes by using enantiopure branched homoallylic alcohols as a source of crotyl groups is discussed. Finally, the synthetic credentials of the developed methodology are illustrated by total syntheses of marine natural products, in which crotylation plays a key role in setting up stereogenic centers.1 Introduction2 Pyridine N-Oxides as Lewis Base Catalysts3 Bipyridine N,N′-Dioxides as Lewis Base Catalysts4 Chiral Allylating Reagents5 Synthetic Applications6 Concluding Remarks

scholarly journals Towards a Paradigm Shift in Polar Organometallic Chemistry

2020 ◽  
Vol 74 (9) ◽  
pp. 681-688 ◽  
Author(s):  
Eva Hevia
Keyword(s):  
Organometallic Chemistry ◽  
Synergistic Effects ◽  
Chemical Properties ◽  
Deep Eutectic Solvents ◽  
Chemical Transformations ◽  
Organometallic Reagents ◽  
Cooperative Effects ◽  
Bond Forming ◽  
Synthetic Methodologies ◽  
Metal Reagents

Core tools of synthetic chemistry, polar organometallic reagents (typified by organolithium and Grignard reagents) are used worldwide for constructing compounds, especially aromatic compounds, which are ubiquitous in organic chemistry and thus in numerous commodities essential to everyday life. By isolation and characterisation of key organometallic intermediates, research in our group has led to the design of polar mixed-metal reagents imbued with synergistic effects that display chemical properties and reactivity profiles far exceeding the limits of traditional single-metal reagents. These studies have improved existing, or established new fundamentally important, synthetic methodologies based on either stoichiometric or catalytic reactions. Bimetallic cooperative effects have been demonstrated in an impressive array of important bond forming reactions including deprotonative metallation, transition metal-free C–C bond formation and metal–halogen exchange to name just a few. Towards greener, more sustainable, safer chemical transformations, our group has also pioneered the use of polar organometallic reagents under air and/or with water present using biorenewable solvents such as Deep Eutectic Solvents (DES) and 2-methyl THF. Herein we summarize some of our recent efforts in this intriguing area, which we believe can make inroads towards a step change in the practice and future scope of polar organometallic chemistry.

Diastereoselective Addition of Organometallic Reagents to Nor-Ephedrine-Derived 2-Acyl-N-Tosyl-Oxazolidines

Synlett ◽  
1995 ◽  
Vol 1995 (01) ◽  
pp. 71-73 ◽  
Author(s):  
Giovanni Poli ◽  
Elisa Maccagni ◽  
Leonardo Manzoni ◽  
Tullio Pilati ◽  
Carlo Scolastico
Keyword(s):  
Organometallic Reagents ◽  
Diastereoselective Addition

scholarly journals Intra- and Interspecies Signaling betweenStreptococcus salivarius and Streptococcus pyogenes Mediated by SalA and SalA1 Lantibiotic Peptides

2001 ◽  
Vol 183 (13) ◽  
pp. 3931-3938 ◽  
Author(s):  
M. Upton ◽  
J. R. Tagg ◽  
P. Wescombe ◽  
H. F. Jenkinson
Keyword(s):  
Streptococcus Pyogenes ◽  
Response Regulator ◽  
Genetic Locus ◽  
Two Component System ◽  
Peptide Modification ◽  
Insertional Inactivation ◽  
Two Component ◽  
Genes Encoding ◽  
Dose Dependent

ABSTRACT Streptococcus salivarius 20P3 produces a 22-amino-acid residue lantibiotic, designated salivaricin A (SalA), that inhibits the growth of a range of streptococci, including all strains ofStreptococcus pyogenes. Lantibiotic production is associated with the sal genetic locus comprisingsalA, the lantibiotic structural gene; salBCTXgenes encoding peptide modification and export machinery proteins; andsalYKR genes encoding a putative immunity protein and two-component sensor-regulator system. Insertional inactivation ofsalB in S. salivarius 20P3 resulted in abrogation of SalA peptide production, of immunity to SalA, and ofsalA transcription. Addition of exogenous SalA peptide tosalB mutant cultures induced dose-dependent expression ofsalA mRNA (0.2 kb), demonstrating that SalA production was normally autoregulated. Inactivation of salR encoding the response regulator of the SalKR two-component system led to reduced production of, and immunity to, SalA. The sal genetic locus was also present in S. pyogenes SF370 (M type 1), but because of a deletion across the salBCT genes, the corresponding lantibiotic peptide, designated SalA1, was not produced. However, in S. pyogenes T11 (M type 4) the sallocus gene complement was apparently complete, and active SalA1 peptide was synthesized. Exogenously added SalA1 peptide from S. pyogenes T11 induced salA1 transcription in S. pyogenes SF370 and in an isogenic S. pyogenes T11salB mutant and salA transcription in S. salivarius 20P3 salB. Thus, SalA and SalA1 are examples of streptococcal lantibiotics whose production is autoregulated. These peptides act as intra- and interspecies signaling molecules, modulating lantibiotic production and possibly influencing streptococcal population ecology in the oral cavity.

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