Preparation of heterocyclic amino acids via intramolecular mukaiyama aldol condensation: Synthesis of a novel cycloleucine analogue

1989 ◽  
Vol 30 (10) ◽  
pp. 1181-1184 ◽  
Author(s):  
Daniel M. Walker ◽  
Eugene W. Logusch
Keyword(s):  
Amino Acids ◽  
Aldol Condensation ◽  
Mukaiyama Aldol

scholarly journals Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ6-sulfanyl)acetic acid esters with aldehydes

2018 ◽  
Vol 14 ◽  
pp. 373-380 ◽  
Author(s):  
Anna-Lena Dreier ◽  
Andrej V Matsnev ◽  
Joseph S Thrasher ◽  
Günter Haufe
Keyword(s):  
Acetic Acid ◽  
Aldol Condensation ◽  
Aldol Reactions ◽  
Complex Structures ◽  
Bond Forming ◽  
Hydroxyalkanoic Acid ◽  
Mukaiyama Aldol ◽  
Substituted Benzaldehydes ◽  
Acetic Acid Esters ◽  
Acid Esters

Aldol reactions belong to the most frequently used C–C bond forming transformations utilized particularly for the construction of complex structures. The selectivity of these reactions depends on the geometry of the intermediate enolates. Here, we have reacted octyl pentafluoro-λ6-sulfanylacetate with substituted benzaldehydes and acetaldehyde under the conditions of the silicon-mediated Mukaiyama aldol reaction. The transformations proceeded with high diastereoselectivity. In case of benzaldehydes with electron-withdrawing substituents in the para-position, syn-α-SF5-β-hydroxyalkanoic acid esters were produced. The reaction was also successful with meta-substituted benzaldehydes and o-fluorobenzaldehyde. In contrast, p-methyl-, p-methoxy-, and p-ethoxybenzaldehydes led selectively to aldol condensation products with (E)-configured double bonds in 30–40% yields. In preliminary experiments with an SF5-substituted acetic acid morpholide and p-nitrobenzaldehyde, a low amount of an aldol product was formed under similar conditions.

Recent advancement and novel application of organocatalyzed aldol condensation reactions: A comprehensive review

2022 ◽  
Vol 19 ◽  
Author(s):  
Ajay Kumar Verma ◽  
Braj Nandan Kishor ◽  
Om Prakash
Keyword(s):  
Amino Acids ◽  
Aldol Condensation ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Addition Product ◽  
Aldol Reactions ◽  
Hydroxy Ketone ◽  
Unsaturated Ketone ◽  
Condensation Reactions ◽  
Aldol Condensation Reactions

Background: Aldol reactions play an important role in the development of organic synthesis-owing to their critical importance for the forming of carbon-carbon bonds while concurrently one or two chiral centers come into being. In the modern scenario, the Aldol condensation reaction has arisen as perhaps the most significant reaction for the formation of novel medicinal agents exhibits promising pharmacological activities. Objective: The purpose of this study is to present newer synthetic approaches through Aldol condensation reaction for the synthesis of diverse scaffolds to explore the promising various types of biological activities. Methods: Aldol condensation concerns the nucleophilic addition reaction of a ketone enolate to an aldehyde to form aldol or β- hydroxy ketone. Occasionally, the aldol addition product losing water molecule yields an α, β-unsaturated ketone. Results: Results showed that amino acids and all lengths of peptides are utilized as chiral catalysts. As of now, the arrangement of catalysts that have been accounted for is intensely one-sided towards proline. This is to some degree because of its exceptional status among the normally happening amino acids as an auxiliary amine and to its restricted underlying adaptability. Conclusion: The present study thus provides useful insight concerning the promising coherent way for the synthesis of prolinamide analogue of proline, through a direct asymmetric aldol condensation reaction. Thus, the current study summarizes various Aldol condensation reactions for the synthesis of novel agents as well as their promising pharmacological importance.

The Paterson Synthesis of (−)-Leiodermatolide

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Aldol Condensation ◽  
Oxidative Cleavage ◽  
Magnesium Bromide ◽  
Silyl Ether ◽  
Enantiomerically Pure ◽  
University Of Cambridge ◽  
Mukaiyama Aldol ◽  
Hydride Elimination ◽  
Reduced Toxicity ◽  
The University

(−)-Leiodermatolide 4, isolated from the lithistid sponge Leiodermatium sp., showed 5.0-nM activity against PANC-1 pancreatic carcinoma cells, and reduced toxicity toward normal cells. Ian Paterson of the University of Cambridge established (Angew. Chem. Int. Ed. 2014, 53, 2692) a synthetic route to 4 based on sp2–sp2 coupling, as exemplified by the combination of 1 with 2 to give 3. Addition of the boron enolate of the enantiomerically-pure benzoate 5 to the iodoaldehyde 6 gave 7, that was silylated, reduced, and deprotected to give 1. Addition of the boron enolate of ent-5 to propanal gave 8. The α-acyloxy ketone of 8 served as a masked acylating agent. The addition of allyl magnesium bromide followed by oxidative cleavage led to the ketone 9. The preparation of 2 was com­pleted by diastereoselective Mukaiyama aldol condensation of 9 with the ketene silyl acetal 10. The intramolecular Heck coupling of 1 with 2 presumably proceeded by way of the organo-Pd intermediate 11. β-Hydride elimination could have given one or more of four possible dienes, but in fact the E,E product 3 dominated, as expected. The allylic H’s are activated for elimination, while the H’s β to the silyl ether are deacti­vated both electronically and sterically. The third component of 4 was the stannane 17. Applying the same strategy, the addition of ent-5 to the aldehyde 12 gave 13, that was protected and condensed with 14 to deliver, after oxidative cleavage, the alkynyl ketone 15. Conjugate addition of iodide proceeded with good geometric control to give 16, that was protected and stan­nylated to complete the preparation of 17. The diol 3 was oxidatively cleaved, and the resulting aldehyde was carried on to the iodide 18. This was coupled with the stannane 17 to give the diene 19. A sequence of deprotection, oxidation, and further deprotection yielded a tetraol, that was lac­tonized with high selectivity to give the 16-membered ring of (−)-leiodermatolide 4.

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