Synthesis of an Enantiomerically Pure Inherently Chiral Calix[4]Arene Phosphonic Acid and Its Evaluation as an Organocatalyst

2018 ◽  
Vol 83 (3) ◽  
pp. 1146-1153 ◽  
Author(s):  
Andrii Karpus ◽  
Oleksandr Yesypenko ◽  
Vyacheslav Boiko ◽  
Jean-Claude Daran ◽  
Zoia Voitenko ◽  
...  
Keyword(s):  
Phosphonic Acid ◽  
Enantiomerically Pure ◽  
Inherently Chiral

Synthesis of enantiomerically pure inherently chiral calix[4]arenes using the meta-substitution strategy

2019 ◽  
Vol 60 (3) ◽  
pp. 260-263 ◽  
Author(s):  
Martin Tlustý ◽  
Dita Spálovská ◽  
Martin Babor ◽  
Pavel Lhoták
Keyword(s):  
Enantiomerically Pure ◽  
Inherently Chiral

The Betzer and Ardisson Synthesis of (+)-Discodermolide

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Selective Hydrogenation ◽  
Geometric Control ◽  
Unsaturated Ester ◽  
Partial Hydrogenation ◽  
Central Feature ◽  
Repeated Application ◽  
Enantiomerically Pure ◽  
The Third ◽  
Carbon Carbon Bond ◽  
Inherently Chiral

( + )-Discodermolide 3, a potent anticancer agent that works synergistically with taxol, may yet prove to be clinically effective. For the synthetic material to be affordable, a highly convergent synthesis is required. Jean-François Betzer and Janick Ardisson of the Université de Cergy- Pontoise have described (Angew. Chem. Int. Ed. 2007, 46, 1917) such a synthesis, coupling 1 and 2. A central feature of their approach was the repeated application of the inherently chiral secondary organometallic reagent 5. The first use of 5 was the addition to the aldehyde 4. The product 6 was ozonized, and the resulting aldehyde was carried on to the α, β-unsaturated ester. Exposure of the hydroxy ester to benzaldehyde under basic conditions delivered, by intramolecular Michael addition, the acetal 7. The next addition of the reagent 5 was to the aldehyde 10. The adduct 11 was deprotonated with t-BuLi to effect α-elimination, providing, after protection of the alcohol, the alkyne 12. Coupling of 12 with the amide 7 gave a ketone, enantioselective reduction of which under Itsuno-Corey conditions led, again after protection of the alcohol, to the alkyne 13. Oxidation followed by selective hydrogenation and iodine-tin exchange then completed the assembly of 1. Note that PtO2, not typically used for partial hydrogenation, was the catalyst of choice for this congested alkyne. The third application of the enantiomerically-pure reagent 5 was addition to the aldehyde that had been prepared by ozonolysis of 15. Advantage was then taken of another property of the alkenyl carbamate, Ni-mediated Grignard coupling, to form the next carbon-carbon bond with high geometric control. Deprotection of the diene 17 so prepared followed by iodination then completed the synthesis of 2. The convergent coupling of 1 with 2 was carried out under Suzuki conditions. Reduction of the iodide of 2 to the corresponding alkyl lithium followed by exchange with B-OMe-9-BBN gave an intermediate organoborane, that smoothly coupled with 1 under Pd catalysis to give 18.

The journey of l-tartaric acid in the world of enantiomerically pure bis- and trisadducts of C60 with the inherently chiral trans-3 and all-trans-3 addition patterns

2014 ◽  
Vol 12 (43) ◽  
pp. 8574-8579 ◽  
Author(s):  
Nikos Chronakis
Keyword(s):  
Tartaric Acid ◽  
Enantiomerically Pure ◽  
The World ◽  
Inherently Chiral

The journey of l-tartaric acid through its derivative (−)-dimethyl-2,3-O-isopropylidene-l-tartrate in the synthesis of enantiomerically pure diols, cyclo-[n]-malonates and finally, inherently chiral trans-3 bisadducts and all-trans-3 trisadducts of C60 is presented.

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