Abstract
Small ring heterocycles, such as epoxides and aziridines, are present in several natural products and are also highly versatile building blocks, frequently involved in the synthesis of numerous bioactive products and pharmaceuticals. Because of the potential for increased efficiency and selectivity, along with the advantages of environmentally benign synthetic procedures, multicomponent reactions (MCRs) have been explored in the synthesis and ring opening of these heterocyclic units. In this review, the recent advances in MCRs involving the synthesis and applications of epoxides and aziridines to the preparation of other heterocycles are discussed emphasizing the stereoselectivity of the reactions.
Highlights
Heterocyclic compounds are very important due to their biological and/or pharmacological properties
The following examples of enzymatic inhibitors deserve mention: scyphostatin, which was isolated from a mycelial extract of Trichopeziza mollissima by Nara et al in 1999, is a neutral sphingomyelinase inhibitor [2]; and E-64, a promiscuous irreversible cysteine protease inhibitor that is broadly reactive toward the papain family, was isolated from Aspergillus japonicus in 1978 by Hanada et al [3]
Concerning the aziridine rings, we should emphasize the antitumor antibiotics mitomycin C, isolated from cultures of Streptomyces caespitosus, that has been used in combination chemotherapy for a variety of tumors and as an antifibrotic agent for several surgical procedures [5]; and azinomycin B, a remarkable natural product containing both epoxide and aziridine rings in its structure, originally isolated from Streptomyces sahachiroi (Figure 1) [6]
Summary
Heterocyclic compounds are very important due to their biological and/or pharmacological properties. Of the advantages of environmentally benign synthetic procedures and catalyst reusability, association three‐component reactions of amines, epoxides, and carbon dioxide have emerged as a powerful heterogeneous catalysis and MCRs have been explored [26,27]. Generated the aryne to the aziridine substituted with an electron withdrawing group (EWG) generated the zwitterionic zwitterionicspecies speciesA; A;,the theintramolecular intramolecularproton protontransfer transferprovided providedaastrained strainedaziridine aziridineylide ylideBB which whichadded addedtotothe thecarbonyl carbonylcomponent, component,and andthe theresulting resultingalkoxide alkoxideCCpromoted promotedthe theaziridine aziridinering ring opening and further epoxide closure. This elegant approach furnished the desired epoxides in good opening and further epoxide closure.
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