scholarly journals α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

2021 ◽  
Vol 17 ◽  
pp. 2570-2584
Author(s):  
Scott Benz ◽  
Andrew S Murkin
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Hydroxy Group ◽  
Tandem Reactions ◽  
Aryl Group ◽  
The Past

In the presence of a suitable acid or base, α-hydroxyaldehydes, ketones, and imines can undergo isomerization that features the 1,2-shift of an alkyl or aryl group. In the process, the hydroxy group is converted to a carbonyl and the aldehyde/ketone or imine is converted to an alcohol or amine. Such α-ketol/α-iminol rearrangements are used in a wide variety of synthetic applications including asymmetric synthesis, tandem reactions, and the total synthesis and biosynthesis of natural products. This review explores the use of α-ketol rearrangements in these contexts over the past two decades.

scholarly journals Unified divergent strategy towards the total synthesis of the three sub-classes of hasubanan alkaloids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guang Li ◽  
Qian Wang ◽  
Jieping Zhu
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Michael Addition ◽  
Total Syntheses ◽  
Bond Forming ◽  
The Past ◽  
Tricyclic Compounds

AbstractElegant asymmetric synthesis of hasubanan alkaloids have been developed over the past decades. However, a divergent approach leading to all three sub-classes of this family of natural products remains unknown. We report herein the realization of such an endeavor by accomplishing enantioselective total syntheses of four representative members. The synthesis is characterized by catalytic enantioselective construction of the tricyclic compounds from which three different intramolecular C-N bond forming processes leading to three topologically different hasubanan alkaloids are developed. An aza-Michael addition is used for the construction of the aza-[4.4.3]-propellane structure of (-)-cepharamine, whereas an oxidation/double deprotection/intramolecular hemiaminal forming sequence is developed to forge the bridged 6/6/6/6 tetracycle of (-)-cepharatines A and C and a domino bromination/double deprotection/cyclization sequence allows the build-up of the 6/6/5/5 fused tetracyclic structure of (−)-sinoracutine.

scholarly journals Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

2014 ◽  
Vol 10 ◽  
pp. 1228-1232 ◽  
Author(s):  
Jens Schmidt ◽  
Zeinab Khalil ◽  
Robert J Capon ◽  
Christian B W Stark
Keyword(s):  
Antibacterial Activity ◽  
Natural Products ◽  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Natural Product ◽  
Joint Effort ◽  
Natural Product Biosynthesis ◽  
New Members ◽  
Degree Of Oxidation ◽  
Rare Class

The heronapyrroles A–C have first been isolated from a marine-derived Streptomyces sp. (CMB-0423) in 2010. Structurally, these natural products feature an unusual nitropyrrole system to which a partially oxidized farnesyl chain is attached. The varying degree of oxidation of the sesquiterpenyl subunit in heronapyrroles A–C provoked the hypothesis that there might exist other hitherto unidentified metabolites. On biosynthetic grounds a mono-tetrahydrofuran-diol named heronapyrrole D appeared a possible candidate. We here describe a short asymmetric synthesis of heronapyrrole D, its detection in cultivations of CMB-0423 and finally the evaluation of its antibacterial activity. We thus demonstrate that biosynthetic considerations and the joint effort of synthetic and natural product chemists can result in the identification of new members of a rare class of natural products.

Total synthesis of desoxycyclomarin C and the cyclomarazines A and B

2016 ◽  
Vol 14 (25) ◽  
pp. 6055-6064 ◽  
Author(s):  
Philipp Barbie ◽  
Uli Kazmaier
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Hydroxy Group ◽  
Tuberculosis Activity

Removing the β-hydroxy group from the prenylated tryptophan moiety of cyclomarins simplifies the synthesis of these interesting natural products significantly, without having a noteworthy effect on the anti-tuberculosis activity of the cyclomarins.

Tandem allylboration-ring-closing metathesis reactions for the preparation of biologically active molecules

2003 ◽  
Vol 75 (9) ◽  
pp. 1263-1275 ◽  
Author(s):  
P. Veeraraghavan Ramachandran ◽  
M. Venkat Ram Reddy ◽  
Herbert C. Brown
Keyword(s):  
Organic Chemistry ◽  
Natural Products ◽  
Asymmetric Synthesis ◽  
Biologically Active ◽  
Cyclic Ethers ◽  
Ring Closing Metathesis ◽  
The Past ◽  
Metathesis Reactions

The development of asymmetric synthesis during the past two decades aided organic chemists considerably in the synthesis of complex natural products. Organoborane chemistry continues to play an important role in asymmetric synthesis. One of the important reactions that has become very common in the arsenal of synthetic chemists is allylboration and related reactions. Another important reaction that has recently attained enormous importance in organic chemistry is the ring-closing metathesis (RCM) reaction. Indeed, a combination of allylboration and RCM reactions provides an excellent route to cyclic ethers, lactones, lactams, etc. Herein, we describe a sequential asymmetric allylboration and RCM reaction protocol that has been utilized for the synthesis of several alpha-pyrone-containing natural products,particularly biologically active molecules.

Total Synthesis of Bis-anthraquinone Antibiotic BE-43472B

Synthesis ◽  
2018 ◽  
Vol 50 (13) ◽  
pp. 2490-2515 ◽  
Author(s):  
Yu Yamashita ◽  
Yoichi Hirano ◽  
Akiomi Takada ◽  
Hiroshi Takikawa ◽  
Keisuke Suzuki
Keyword(s):  
Total Synthesis ◽  
Hydroxy Group ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Aryl Group ◽  
Full Account ◽  
Ring Fusion ◽  
Enantiomerically Pure ◽  
Pinacol Rearrangement ◽  
Key Steps

This is a full account of our synthetic endeavor on the total synthesis of bis-anthraquinone antibiotic BE-43472B, an unusual octacyclic aromatic polyketide with a bis-anthraquinone scaffold. Three key steps enabled a facile access to the anthraquinone unit corresponding to the ABCF rings; (1) cyclo-condensation or -addition of benzonitrile oxides with cyclic enone derivatives, (2) benzoin cyclization for the stereoselective ring fusion with an angular hydroxy group, and (3) pinacol rearrangement for stereoselective installation of the angular aryl group. Other keys for the success include, (4) diastereoselective methylation of a lactol derivative, and (5) late-stage installation of the C3 hydroxy group through stereoselective oxirane ring formation via halohydrin derivatives. Whereas oxidation of the double bond in the enone with an adjacent 1,3-diketone moiety failed, the projected oxidation was achieved with the alkene keeping the isoxazole moiety intact as a 1,3-diketone equivalent. In the racemic total synthesis, X-ray crystal structure analysis of the target was achieved, proving the three-dimensional architecture for the first time. The asymmetric total synthesis was also achieved by exploiting a cycloadduct of the nitrile oxide and the enantiomerically pure cyclohexenone, which was convertible to the common intermediate via dehydrogenation followed by alkoxycarbonylation.

Synthesis of α-exo-Methylene-γ-butyrolactone: Recent Developments and Applications in Natural Product Synthesis

Synthesis ◽  
2021 ◽  
Author(s):  
Weilong Liu ◽  
Nicolas Winssinger
Keyword(s):  
Natural Products ◽  
Biological Activity ◽  
Total Synthesis ◽  
Natural Product ◽  
Natural Product Synthesis ◽  
Vast Array ◽  
The Past ◽  
New Approaches ◽  
Recent Developments

The α-exo-methylene-γ-butyrolactone moiety is present in a vast array of structurally diverse natural products and is often central to their biological activity. In this review, we summarize new approaches to α-exo-methylene-γ-butyrolactones developed over the past decade as well as their applications in total synthesis.

scholarly journals A Review of the Pharmacological Activities and Recent Synthetic Advances of γ-Butyrolactones

2021 ◽  
Vol 22 (5) ◽  
pp. 2769
Author(s):  
Joonseong Hur ◽  
Jaebong Jang ◽  
Jaehoon Sim
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Small Molecules ◽  
Biologically Active ◽  
Synthetic Methods ◽  
Pharmacological Activities ◽  
New Developments ◽  
The Past ◽  
Privileged Structures ◽  
Significant Attention

γ-Butyrolactone, a five-membered lactone moiety, is one of the privileged structures of diverse natural products and biologically active small molecules. Because of their broad spectrum of biological and pharmacological activities, synthetic methods for γ-butyrolactones have received significant attention from synthetic and medicinal chemists for decades. Recently, new developments and improvements in traditional methods have been reported by considering synthetic efficiency, feasibility, and green chemistry. In this review, the pharmacological activities of natural and synthetic γ-butyrolactones are described, including their structures and bioassay methods. Mainly, we summarize recent advances, occurring during the past decade, in the construction of γ-butyrolactone classified based on the bond formation in γ-butyrolactone between (i) C5-O1 bond, (ii) C4-C5 and C2-O1 bonds, (iii) C3-C4 and C2-O1 bonds, (iv) C3-C4 and C5-O1 bonds, (v) C2-C3 and C2-O1 bonds, (vi) C3-C4 bond, and (vii) C2-O1 bond. In addition, the application to the total synthesis of natural products bearing γ-butyrolactone scaffolds is described.

Enantioselective Syntheses of Yohimbine Alkaloids: Proving Grounds for New Catalytic Transformations

Synthesis ◽  
2021 ◽  
Author(s):  
Karl A. Scheidt ◽  
Eric R Miller
Keyword(s):  
Natural Products ◽  
Chemical Synthesis ◽  
Total Synthesis ◽  
State Of The Art ◽  
The State ◽  
Catalytic Transformations ◽  
Bond Forming ◽  
The Past ◽  
Catalytic Asymmetric ◽  
Enantioselective Syntheses

The total synthesis of bioactive alkaloids is an enduring challenge and an indication of the state of the art of chemical synthesis. With the explosion of catalytic asymmetric methods over the past three decades, these compelling targets have been fertile proving grounds for enantioselective bond forming transformations. We summarize these activities herein both to highlight the power and versatility of these methods and to instill future inspiration for new syntheses of these privileged natural products.

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