The taxol side chain (S(R),2R,3S)-N-tert-butanesulfinyl-O-Boc-3-phenylisoserine benzyl ester 4c was synthesized through a lithium enolate addition of O-Boc-alpha-hydroxyacetate benzyl ester 5c to benzylidene (S(R))-tert-butanesulfinamide 6a in excellent yield and diastereoselectivity. By similar approach, a series of enantiopure 3-substituted isoserine benzyl esters 4 useful for the semi-syntheses of taxol derivatives were also prepared in high to excellent yields and diastereoselectivities. The diastereoselective addition mechanism was discussed on the basis of the experimental observation.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jo052298n | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Sulfur Analogs of the Core Formose Cycle: A Free Energy Map.
Life (Basel)
December 2024
Department of Chemistry & Biochemistry, University of San Diego, San Diego, CA 92110, USA.
Using computational methods, we examine if the presence of HS can tame the unruly formose reaction by generating a free energy map of the reaction thermodynamics and kinetics of sulfur analogs within the core cycle. With mercaptoaldehyde as the linchpin C species, and feeding the cycle with CHO, selected aldol additions and enolizations are kinetically more favorable. Thione formation is thermodynamically less favored compared to aldehydes and ketones, but all these species can be connected by enolization reactions.
View Article and Find Full Text PDFHomo-Mannich Reaction of Cyclopropanols: A Versatile Tool for Natural Product Synthesis.
Acc Chem Res
January 2025
Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China.
ConspectusThe Mannich reaction, involving the nucleophilic addition of an enol(ate) intermediate to an imine or iminium ion, is one of the most widely used synthetic methods for the synthesis of β-amino carbonyl compounds. Nevertheless, the homo-Mannich reaction, which utilizes a homoenolate intermediate as the nucleophilic partner and provides straightforward access to the valuable γ-amino carbonyl compounds, remains underexplored. This can be largely attributed to the difficulties in generation and manipulation of the homoenolate species, despite various homoenolate equivalents that have been developed.
View Article and Find Full Text PDFCatalytic Enantioselective Synthesis of 1,4-(Hetero) Dicarbonyl Compounds through α-Carbonyl Umpolung.
J Am Chem Soc
January 2025
Institute of Organic Chemistry, University of Leipzig, 04103 Leipzig, Germany.
The enantioselective synthesis of 1,4-dicarbonyl compounds continues to pose a significant challenge in organic synthesis, and a catalytic process which generates two adjacent stereogenic centers with full stereochemical control is lacking until now. The 1,4-relationship of the functional groups requires an Umpolung strategy as one of the α-carbonyl positions has to be inverted into an electrophilic center to react with a normal enolate. We report herein the highly enantio- and diastereoselective addition of silyl ketene acetals toward electrophilic 1-azaallyl cations to furnish chiral 4-hydrazonoesters, which are masked 1,4-dicarbonyl compounds.
View Article and Find Full Text PDFSynthesis and LDHA Inhibitory Activity of New Stiripentol-Related Compounds of Potential Use in Primary Hyperoxaluria.
Int J Mol Sci
December 2024
Department of Inorganic and Organic Chemistry, Faculty of Experimental Sciences, University of Jaén, Campus of International Excellence in Agri-Food (ceiA3), 23071 Jaén, Spain.
Human lactate dehydrogenase A (LDHA) is a homotetrameric isozyme involved in the conversion of glyoxylate into oxalate in the cytosol of liver cells (hepatocytes) and partially responsible for the overproduction of oxalate in patients with the rare disease called primary hyperoxaluria (PH). Recently, LDHA inhibition has been validated as a safe therapeutic method to try to control the PH disease. Stiripentol (STP) is an approved drug used in the treatment of seizures associated with Dravet's syndrome (a severe form of epilepsy in infancy) which, in addition, has been drawing interest in recent years also for potentially treating PH, due to its LDHA inhibitory activity.
View Article and Find Full Text PDFTotal syntheses of the parvistemoline alkaloids enabled by stereocontrolled Ir/Pd-catalyzed allylic alkylation.
Nat Commun
December 2024
Key Laboratory of Phytochemistry and Natural Medicines, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China.
The functionalized polycycle with densely contiguous tertiary stereocenters is a formidable challenge in synthesizing the parvistemoline family of Stemona alkaloids. We herein report their catalytic, asymmetric total syntheses in 13-14 steps from commercially available 2-(methoxycarbonyl)-pyrrole, featuring the development and deployment of an Ir/Pd-synergistically-catalyzed allylation of α-non-substituted keto esters with secondary aryl-substituted alcohols, stereodivergently accessible to four stereoisomers. Using chiral Pd-enolate and Ir π-allyl complex under neutral conditions, no epimerization occurs.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!