| 1. |
- Danielsson, Jakob, et al.
(författare)
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Total Synthesis of Dehaloperophoramidine : Evolution of a Synthesis
- 2017
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Ingår i: Strategies and Tactics in Organic Synthesis. - 1874-6004. ; 13, s. 217-242
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Bokkapitel (refereegranskat)abstract
- This account describes our efforts toward developing a stereodivergent entry to perophoramidine and the communesin alkaloids. The original approach toward our simplified model substrates relied on a palladium-catalyzed carbopalladation–carbonylation of a tetrasubstituted olefin to install the vicinal all-carbon quaternary stereocenters present in the target molecules, the olefin's stereochemistry thus dictating the relative stereochemistry of the quaternary stereocenters. Although the carbonylation–carbopalladation sequence worked well for trisubstituted olefins, only premature esterification was observed when using tetrasubstituted alkene substrates. Our second approach made use of the latent symmetry embedded in our target molecules. A Diels–Alder reaction or SmI2-mediated bis-alkylation of isoindigo was to be used to access the communesin and perophoramidine scaffolds, respectively. We found that due to unfavorable thermodynamics, it was not possible to reach the communesin scaffold. However, two new complexity-generating, cascade reactions were encountered en route to the synthesis of dehaloperophoramidine, resulting in a short and efficient synthesis.
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| 2. |
- Hoang, Anita, et al.
(författare)
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An Efficient Synthesis of (±)-Dehaloperophoramidine
- 2017
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 82:4, s. 2171-2176
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Tidskriftsartikel (refereegranskat)abstract
- Perophoramidine and communesin F are structurally related indole alkaloids with an intriguing polycyclic core containing vicinal all-carbon quaternary stereocenters. Dehaloperophoramidine is a dehalogenated synthetic analogue of perophoramidine. Synthetic studies toward the total synthesis of dehaloperophoramidine have led to the discovery of two novel domino processes, the first encompassing four steps and resulting in the formation of an ortho-amide. A thorough study of the reactivity of the ortho-amide functionality revealed the second domino reaction and ultimately yielded the target molecule. The vicinal all-carbon quaternary stereocenters having trans relative stereochemistry are constructed early in the reaction sequence by employing Overman's samarium mediated reductive dialkylation procedure. Described are the synthetic studies that led to the final eight-step synthesis of dehaloperophoramidine.
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| 3. |
- Popov, Kirill, et al.
(författare)
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Concise Total Synthesis of Dehaloperophoramidine.
- 2015
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Ingår i: Angewandte Chemie (International edition). - : Wiley. - 1521-3773.
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Tidskriftsartikel (refereegranskat)abstract
- Perophoramidine, dehaloperophoramidine, and communesin F are structurally related alkaloids having intriguing polycyclic structures. A strategy for the synthesis of dehaloperophoramidine has been developed. In this synthesis all skeletal atoms and all functional groups required to reach the target molecule are incorporated early in the sequence. This approach led to the discovery of two novel substrate-specific domino processes, one encompassing four steps and the other comprising five steps, thus resulting in an eight-step synthesis of dehaloperophoramidine.
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| 4. |
- Popov, Kirill, et al.
(författare)
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Synthesis of Imidates : TFA-Mediated Regioselective Amide Alkylation Using Meerwein's Reagent
- 2016
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 81:8, s. 3470-3472
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Tidskriftsartikel (refereegranskat)abstract
- Regioselective O-alkylation of an amide to form the corresponding imidate is a common synthetic problem, often resulting in varying amounts of N-alkylation. Screening existing methods for converting amides to imidates gave inconsistent or irreproducible results, sometimes affording N-alkylamide as the major product. A simple and reliable protocol for amide O-alkylation with complete regioselectivity has been designed, and its scope and efficiency demonstrated on a number of substrates.
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| 5. |
- Sanzone, Angelo, et al.
(författare)
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A Diels-Alder Approach to a Communesin Model: A/B-Cyclization Route
- 2015
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X. ; :16, s. 3441-3449
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Tidskriftsartikel (refereegranskat)abstract
- Compound 3, a model system for communesin F, was approached by using a Diels-Alder reaction for the introduction of the vicinal quaternary stereocentres. Subsequent introduction of A/B-ring system followed by D/E-ring closure gave hexacyclic system 22. All attempts to reduce this material to give compound 3 were, however, unproductive.
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| 6. |
- Yu, Lu, et al.
(författare)
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Enantioselective synthesis of : Anti -3-alkenyl-2-amido-3-hydroxy esters: Application to the total synthesis of (+)-alexine
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 9:5, s. 2799-2802
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Tidskriftsartikel (refereegranskat)abstract
- A straightforward synthesis of anti-3-alkenyl-2-amido-3-hydroxy esters from the corresponding racemic α-amino-β-keto esters by using a ATH/DKR protocol has been developed. This method gives moderate to excellent yields with high chemo-, diastereo- and enantioselectivities for a broad range of substrates. In order to highlight the versatility of the methodology it was applied in an efficient asymmetric synthesis of the polyhydroxylated pyrrolizidine alkaloid (+)-alexine.
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| 7. |
- Yu, Lu, et al.
(författare)
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Regio- and Enantioselective Formal Hydroamination of Enamines for the Synthesis of 1,2-Diamines
- 2019
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 58:25, s. 8551-8555
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Tidskriftsartikel (refereegranskat)abstract
- The asymmetric formal hydroamination of enamines using a CuH catalyst is reported. The method provides a straightforward and efficient approach to the synthesis of chiral 1,2-dialkyl amines in good yields with high levels of enantioselectivities for a broad range of substrates, and should have significant value for the preparation of molecules bearing a 1,2-diamine motif.
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| 8. |
- Yu, Lu, et al.
(författare)
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Synthesis of α-Keto Amides by a Pyrrolidine/TEMPO-Mediated Oxidation of α-Keto Amines
- 2016
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Ingår i: Synlett. - : Georg Thieme Verlag KG. - 0936-5214 .- 1437-2096. ; 27:18, s. 2587-2590
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Tidskriftsartikel (refereegranskat)abstract
- A mild procedure has been developed for the synthesis of α-keto amides by α-oxidation of the corresponding α-keto amines mediated by pyrrolidine and TEMPO. The method can also be applied to the synthesis of α-keto thioamides and α-keto amidines.
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