Generation ofN-Acyliminium Ions via Intramolecular Conjugate Addition Reactions:  A Strategy for the Total Synthesis of Nakadomarin A

2006 ◽  
Vol 8 (17) ◽  
pp. 3833-3836 ◽  
Author(s):  
Mark G. Nilson ◽  
Raymond L. Funk
Keyword(s):  
Total Synthesis ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Acyliminium Ions ◽  
Nakadomarin A

scholarly journals Oxazolidinones as Chiral Auxiliaries in the Asymmetric 1,4-Conjugate Addition Reaction Applied to the Total Synthesis of Natural Products: A Supplemental Mini-Review

2018 ◽  
Vol 15 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Vahideh Zadsirjan ◽  
Majid M. Heravi
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Conjugate Addition ◽  
Chiral Auxiliary ◽  
Addition Reactions ◽  
Chiral Auxiliaries ◽  
Complex Molecules ◽  
Total Syntheses ◽  
Naturally Occurring ◽  
Wide Range

Background: The most frequently used chiral auxiliaries, oxazolidinones (Evans' oxazolidinones) have been employed in 1,4-congugate addition reactions to α,β-unsaturated carbonyl compounds. Supplementary to our previous reports in this mini-review, we attempted to underscore the applications of this strategy in a step (steps) in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Objective: In this mini-review, we try to underscore the applications of oxazolidinones (Evans’ oxazolidinones) in 1,4-congugate addition reactions to α,β-unsaturated carbonyl in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Conclusion: In spite of well-known superiority of asymmetric catalyzed reactions, the use of auxiliarycontrolled reactions are still considered as commanding, vital and sometimes as only tools in the generation of stereogenic centers during the construction of complex molecules and total synthesis of naturally occurring compounds. The commercial availability, or readily accessibility of a wide variety of chiral amino alcohols as starting materials to synthesize a wide range of oxazolidinones is the merits of them. In addition, the ease of removal and subjection to various and diverse stereoselective reactions make oxazolidinones as the ideal and superior chiral auxiliaries. In this regard, they were successfully used in asymmetric 1,4-conjugate addition reactions with high stereoselectivities. The high degree of asymmetric induction can be attributed to the rigid chelation of N-acyloxazolidinones with metal ions, as well as the covering of one face of the system by the bulkiness of 4-substituent. In summary, in this report, the importance of the applications of chiral oxazolidinones as suitable chiral auxiliaries in the stereoselective, 1,4-conjugate addition reactions in asymmetric synthesis and in particular, the total synthesis of naturally occurring compounds and some complex molecules were underscored. Noticeably, in these total syntheses, this chiral auxiliary is controlling the stereochemistry of a newly created stereogenic center as well as preserving the configuration of other chiral centers, which already have been presented in the precursor. General methods have been established for the attachment of the chiral auxiliary as a moiety to the substrate molecule in high to excellent yields. At the end of these reactions, this auxiliary can be easily removed leaving various desired reactive motifs for the next step in multi-step synthesis.

Stereoselective Reactions of ortho-Quinone Methide and ortho-Quinone Methide Imines and Their Utility in Natural Product Synthesis

Synthesis ◽  
2018 ◽  
Vol 50 (20) ◽  
pp. 4008-4018 ◽  
Author(s):  
Alan Spivey ◽  
Christian Nielsen ◽  
Hossay Abas
Keyword(s):  
Total Synthesis ◽  
Conjugate Addition ◽  
Natural Product Synthesis ◽  
Quinone Methide ◽  
Addition Reactions ◽  
Quinone Methides ◽  
New Methods ◽  
Synthetic Utility ◽  
Stereoselective Reactions ◽  
Significant Attention

Herein presented is a review of the reactivity and synthetic utility of ortho-quinone methides and ortho-quinone methide imines. These versatile intermediates have received significant attention in the literature and new methods for their preparation and reaction as well as recent applications in total synthesis are discussed.1 Introduction2 Conjugate Addition Reactions3 Concerted Cycloaddition Reactions4 Stepwise Addition Reactions5 Applications in Total Synthesis6 Conclusion

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