Biocatalytic approaches for enantio and diastereoselective synthesis of chiral β-nitroalcohols

2021 ◽  
Author(s):  
D. H. Sreenivasa Rao ◽  
Ayon Chatterjee ◽  
Santosh Kumar Padhi
Keyword(s):  
Bioactive Molecules ◽  
Diastereoselective Synthesis ◽  
Synthetic Intermediates

Chiral β-nitroalcohols are versatile synthetic intermediates for several pharmaceuticals, and bioactive molecules. This review describes the importance and various biocatalytic approaches for their enantio and diastereoselective synthesis.

scholarly journals Sterically Controlled Late-Stage C–H Alkynylation of Arenes

2019 ◽  
Author(s):  
Arup Mondal ◽  
Hao Chen ◽  
Lea Flämig ◽  
Philipp Wedi ◽  
Manuel van Gemmeren
Keyword(s):  
Organic Chemistry ◽  
Late Stage ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Sonogashira Coupling ◽  
Traditional Methods ◽  
Complementary Product ◽  
Complementary Approach ◽  
Synthetic Intermediates ◽  
Directing Group

Phenylacetylenes are key structural motifs in organic chemistry, which find widespread applications in bioactive molecules, synthetic intermediates, functional materials and reagents. These molecules are typically prepared from pre-functionalized starting materials, e.g. using the Sonogashira coupling, or using directing group-based C–H activation strategies. While highly efficient, these approaches remain limited by their inherent selectivities for specific regioisomers. Herein we present a complementary approach based on an arene-limited nondirected C–H activation. The reaction is predominantly controlled by steric rather than electronic factors and thereby gives access to a complementary product spectrum with respect to traditional methods. A broad scope as well as the suitability of this protocol for late-stage functionalization are demonstrated.<br>

scholarly journals Sterically Controlled Late-Stage C–H Alkynylation of Arenes

2019 ◽  
Author(s):  
Arup Mondal ◽  
Hao Chen ◽  
Lea Flämig ◽  
Philipp Wedi ◽  
Manuel van Gemmeren
Keyword(s):  
Organic Chemistry ◽  
Late Stage ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Sonogashira Coupling ◽  
Traditional Methods ◽  
Complementary Product ◽  
Complementary Approach ◽  
Synthetic Intermediates ◽  
Directing Group

Phenylacetylenes are key structural motifs in organic chemistry, which find widespread applications in bioactive molecules, synthetic intermediates, functional materials and reagents. These molecules are typically prepared from pre-functionalized starting materials, e.g. using the Sonogashira coupling, or using directing group-based C–H activation strategies. While highly efficient, these approaches remain limited by their inherent selectivities for specific regioisomers. Herein we present a complementary approach based on an arene-limited nondirected C–H activation. The reaction is predominantly controlled by steric rather than electronic factors and thereby gives access to a complementary product spectrum with respect to traditional methods. A broad scope as well as the suitability of this protocol for late-stage functionalization are demonstrated.<br>

scholarly journals Facile generation of bridged medium-sized polycyclic systems by rhodium-catalysed intramolecular (3+2) dipolar cycloadditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bao-Long Hou ◽  
Jonathan J. Wong ◽  
Na Lv ◽  
Yong-Qiang Wang ◽  
K. N. Houk ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Single Step ◽  
Bioactive Molecules ◽  
Dipolar Cycloaddition ◽  
General Strategy ◽  
Diastereoselective Synthesis ◽  
Asymmetric Total Synthesis ◽  
Ring Systems ◽  
Dipolar Cycloadditions ◽  
Unusual Type

AbstractBridged medium-sized bicyclo[m.n.2] ring systems are common in natural products and potent pharmaceuticals, and pose a great synthetic challenge. Chemistry for making bicyclo[m.n.2] ring systems remains underdeveloped. Currently, there are no general reactions available for the single-step synthesis of various bridged bicyclo[m.n.2] ring systems from acyclic precursors. Here, we report an unusual type II intramolecular (3+2) dipolar cycloaddition strategy for the syntheses of various bridged bicyclo[m.n.2] ring systems. This rhodium-catalysed cascade reaction provides a relatively general strategy for the direct and efficient regioselective and diastereoselective synthesis of highly functionalized and synthetically challenging bridged medium-sized polycyclic systems. Asymmetric total synthesis of nakafuran-8 was accomplished using this method as a key step. Quantum mechanical calculations demonstrate the mechanism of this transformation and the origins of its multiple selectivities. This reaction will inspire the design of the strategies to make complex bioactive molecules with bridged medium-sized polycyclic systems.

Synthesis of Lactams via Isocyanide-Based Multicomponent Reactions

Synthesis ◽  
2020 ◽  
Author(s):  
Shrikant G. Pharande
Keyword(s):  
Natural Products ◽  
Multicomponent Reactions ◽  
Bioactive Molecules ◽  
Wide Range ◽  
Two Component ◽  
Synthetic Intermediates

AbstractLactams are very important heterocycles as a result of their presence in a wide range of bioactive molecules, natural products and drugs, and also due their utility as versatile synthetic intermediates. Due to these reasons, numerous efforts have focused on the development of effective and efficient methods for their synthesis. Compared to conventional two-component reactions, multicomponent reactions (MCRs), particularly isocyanide-based MCRs, are widely used for the synthesis of a range of small heterocycles including lactam analogues. Despite their numerous applications in almost every field of chemistry, as yet there is no dedicated review on isocyanide-based multicomponent reactions (IMCRs) concerning the synthesis of lactams. Therefore, this review presents strategies towards the synthesis of α-, β-, γ-, δ- and ε-lactams using IMCRs or IMCRs/post-transformation reactions reported in the literature between 2000 and 2020.1 Introduction2 Developments in Lactam Synthesis2.1 α-Lactams2.2 β-Lactams2.3 γ-Lactams2.3.1 General γ-Lactams2.3.2 Benzo-Fused γ-Lactams2.3.3 Spiro γ-Lactams2.3.4 α,β-Unsaturated γ-Lactams2.3.5 Polycyclic Fused γ-Lactams2.4 δ-Lactams2.5 ε-Lactams3 Conclusions

Proline-Catalyzed Asymmetric α-Amination in the Synthesis of Bioactive Molecules

Synlett ◽  
2018 ◽  
Vol 29 (15) ◽  
pp. 1944-1956 ◽  
Author(s):  
Pradeep Kumar ◽  
Brijesh Sharma
Keyword(s):  
Total Synthesis ◽  
Chain Length ◽  
Carbonyl Compounds ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Diastereoselective Synthesis ◽  
One Pot ◽  
Naturally Occurring ◽  
Fused Ring ◽  
Complete Account

The direct α-amination of carbonyl compounds using organocatalysts represents a powerful and atom-economical tool for asymmetric C–N bond formation. We describe a complete account of α-functionalization of carbonyl compounds, through iterative sequential α-aminoxylation/amination using electrophilic O and N sources, as well as sequential α-amination/HWE reaction for enantio- and diastereoselective synthesis of both syn- and anti-1,3-aminoalcohols and 1,3-diamines. Additionally this protocol is further extended for the easy construction of alkaloids such as indolizidine, pyrrolizidine, and quinolizidine fused-ring systems just by tuning the chain length of the aldehyde used as a starting material. This methodology provides further scope to extrapolate it for a variety of naturally occurring hydroxylated monocyclic and fused bicyclic pyrrolidine and piperidine based alkaloids such as lentiginosine, epi-lentiginosine, dihydroxypyrrolizidine, (+)-deoxoprosophylline and (–)-deoxoprosopinine alkaloids. Furthermore, we have also uncovered proline-catalyzed anti-selectivity for the synthesis of 1,2-amino alcohols in α-amination of aldehyde and one-pot indium-mediated Barbier type allylation of α-hydrazino aldehydes to accomplish the total synthesis of clavaminols, sphinganine and spisulosine with reduced number of steps and with high overall yields.1 Introduction2 Application in the Total Synthesis of Alkaloids3 Conclusion

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

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