scholarly journals Asymmetric Synthesis of Seven-Membered Carbocyclic Rings via a Sequential Oxyanionic 5-Exo-Dig Cyclization/Claisen Rearrangement Process. Total Synthesis of (−)-Frondosin B

2009 ◽  
Vol 11 (12) ◽  
pp. 2715-2718 ◽  
Author(s):  
Timo V. Ovaska ◽  
Jonathan A. Sullivan ◽  
Sami I. Ovaska ◽  
Jacob B. Winegrad ◽  
Justin D. Fair
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Claisen Rearrangement ◽  
Rearrangement Process ◽  
Frondosin B ◽  
Carbocyclic Rings

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

Total Synthesis of Icaritin via Microwave-assistance Claisen Rearrangement

2014 ◽  
Vol 11 (9) ◽  
pp. 677-681 ◽  
Author(s):  
Van-Son Nguyen ◽  
Ling Shi ◽  
Yue Li ◽  
Qiu-An Wang
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Microwave Assistance

Synthetic Approaches Towards the Total synthesis of tubulysin and its fragments: A review

2021 ◽  
Vol 19 ◽  
Author(s):  
Nosheen Iqbal ◽  
Ameer Fawad Zahoor ◽  
Nasir Rasool ◽  
Samreen Gul Khan ◽  
Rabia Akhtar ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Antitumor Agents ◽  
Aldol Reaction ◽  
Multidrug Resistant ◽  
Novel Drugs ◽  
Mukaiyama Aldol ◽  
Ic50 Values ◽  
Barbier Reaction ◽  
Synthetic Approaches

Background: Tubulysins, linear tetrapeptides show extraordinary cytotoxicity against various cancer cells, with IC50 values in nano or picomolar range. Due to their extremely vigorous anti-proliferative and antiangiogenic characteristics, tubulysins exhibit captivating prospects in the development of anticancer drugs. This review focuses on diverse routes for the total synthesis of natural and synthetic tubulysins as well as their fragments. Objective: The purpose of this review is to present the synthetic strategies for the development of antitumor agents, tubulysins. Conclusion: A range of synthetic pathways adopted for the total synthesis of tubulysins and their fragments have been described in this review. Synthesis of fragments, Tuv, Tup, and Tut can be accomplished by adopting appropriate strategies such as Manganese-mediated synthesis, Ireland-Claisen rearrangement, Mukaiyama aldol reaction, and Mannich process etc. Tubulysin B, D, U, V, and N14-desacetoxytubulysin H have been prepared through Mitsunobu reaction, tert-butanesulfinamide method, Tandem reaction, aza-Barbier reaction, Evans aldol reaction, and C-H activation strategies etc. The remarkable anticancer potential of tubulysins toward a substantiate target make them prominent leads for developing novel drugs against multidrug-resistant cancers.

A Concise Total Synthesis of (±)-Mesembrine

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1203-1206 ◽  
Author(s):  
Hyoungsu Kim ◽  
Hosam Choi ◽  
Kiyoun Lee
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Allylic Oxidation ◽  
Quaternary Stereocenter

A concise total synthesis of (±)-mesembrine has been successfully accomplished in seven steps and 24% overall yield from commercially available 3-ethoxy-2-cyclohexen-1-one. Central to the assembly of the skeleton of mesembrine are a Johnson–Claisen rearrangement for the formation of the benzylic quaternary stereocenter and direct allylic oxidation to generate the substrate for the amidation/transannular aza-conjugate addition reaction.

ChemInform Abstract: Total Synthesis of (-)-Flustramine B via One-Pot Intramolecular Ullmann Coupling and Claisen Rearrangement.

ChemInform ◽  
2009 ◽  
Vol 40 (41) ◽  
Author(s):  
Tomohiro Hirano ◽  
Kanako Iwakiri ◽  
Hiroshi Miyamoto ◽  
Atsuo Nakazaki ◽  
Susumu Kobayashi
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
One Pot ◽  
Ullmann Coupling
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