Enantiospecific Total Syntheses and Assignment of Absolute Configuration of Cannabinol-Skeletal Carbazole Alkaloids Murrayamines-O and -P

2015 ◽  
Vol 21 (23) ◽  
pp. 8347-8350 ◽  
Author(s):  
Dattatraya H. Dethe ◽  
Saikat Das ◽  
Balu D. Dherange ◽  
Samarpita Mahapatra
Keyword(s):  
Absolute Configuration ◽  
Total Syntheses ◽  
Carbazole Alkaloids

Concise Total Syntheses of Pyr­ido[4,3-b]carbazole Alkaloids Using Copper-Mediated 6π-Electrocyclization

2016 ◽  
Vol 2016 (13) ◽  
pp. 2290-2299 ◽  
Author(s):  
Tomoki Itoh ◽  
Takumi Abe ◽  
Tominari Choshi ◽  
Takashi Nishiyama ◽  
Reiko Yanada ◽  
...  
Keyword(s):  
Total Syntheses ◽  
Carbazole Alkaloids

Synthesis of Naturally Occurring Cyclic Ethers: Boivivianin B (Murakami), SC- Δ 13 -9-IsoF (Taber), Brevisamide (Panek, Lindsley,Ghosh), Gambierol (Mori)

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Absolute Configuration ◽  
Cyclic Ether ◽  
Diels Alder ◽  
Synthetic Methods ◽  
Hydroxy Ketone ◽  
Total Syntheses ◽  
Enantiomerically Pure ◽  
Boston University ◽  
Gambierdiscus Toxicus ◽  
The University

The challenge of controlling the relative and absolute configuration of highly substituted cyclic ether-containing natural products continues to stimulate the development of new synthetic methods. Masahiro Murakami of Kyoto University showed (J. Org. Chem. 2009, 74, 6050) that Rh-mediated addition of an aryl boronic acid to 1 proceeded with high syn diastereocontrol, giving 3. This set the stage for Au-mediated rearrangement, leading to 4. We found (J. Org. Chem. 2009, 74, 5516) that asymmetric epoxidation of 5 followed by exposure to AD-mix could be used to prepare each of the four diastereomers of 6. We carried 6 on the isofuran 7, using a stereodivergent strategy that allowed the preparation of each of the 32 enantiomerically pure diastereomers of the natural product. Following up on the synthesis of brevisamide 16 described (Organic Highlights, November 16, 2009) by Kazuo Tachibana of the University of Tokyo, three groups reported alternative total syntheses. James S. Panek of Boston University prepared (Organic Lett. 2009, 11, 4390) the cyclic ether of 16 by addition of the enantiomerically pure silane 9 to 8. Craig W. Lindsley of Vanderbilt University used (Organic Lett. 2009, 11, 3950) SmI2 to effect the cyclization of 11 to 12. Arun K. Ghosh of Purdue University employed (Organic Lett. 2009, 11, 4164) an enantiomerically pure Cr catalyst to direct the absolute configuration in the hetero Diels-Alder addition of 14 to 13. Rubottom oxidation of the enol ether so formed led to the α-hydroxy ketone 15. Yuji Mori of Meijo University described (Organic Lett. 2009, 11, 4382) the total synthesis of the Gambierdiscus toxicus ladder ether gambierol 19. A key strategy, used repeatedly through the sequence, was the exo cyclization of an epoxy sulfone, illustrated by the conversion of 17 to 18. The epoxy sulfones were prepared by alkylating the anions derived from preformed epoxy sulfones such as 20.

Determination of the Absolute Configuration of Gliomasolide D through Total Syntheses of the C-17 Epimers

2017 ◽  
Vol 80 (2) ◽  
pp. 560-564 ◽  
Author(s):  
B. Seetharamsingh ◽  
Routholla Ganesh ◽  
D. Srinivasa Reddy
Keyword(s):  
Absolute Configuration ◽  
Total Syntheses ◽  
The Absolute
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