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Abstract Ade novoasymmetric strategy for the synthesis ofd‐bradyrhizose diastereomers from an achiral ketoenolester precursor is described. Key transformations used in the stereodivergent approach include two Noyori asymmetric reductions, an Achmatowicz rearrangement, diastereoselective alkene oxidations, and the first example of a palladium(0)‐catalyzed glycosylation of a vinylogous pyranone. The isomeric composition of the bicyclic reducing sugars obtained was analyzed and their behaviour was compared to the natural product, revealing key stereocentres that impact the overall distribution.
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Regiodivergent Asymmetric Pyridinium Additions: Mechanistic Insight and Synthetic Applications
Abstract A practical protocol for the first regiodivergent asymmetric addition of aryl and alkenyl organometallic reagents to substitutedN‐alkyl pyridinium heterocycles is described. The couplings proceed with high regiochemical and stereochemical selectivities, and provide access to chiral 1,2,3‐ and 1,3,4‐trisubstituted dihydropyridine products, controlled by judicious choice of nitrogen activating agent. To this end, a correlation was found between the parameterized size of the activating group and the C2/C4 regioselectivity in the couplings. The utility of the described chemistry was demonstrated in two concise asymmetric syntheses of (+)‐N‐methylaspidospermidine and (−)‐paroxetine.
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- Award ID(s):
- 2154662
- PAR ID:
- 10384873
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 28
- Issue:
- 69
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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