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T1 - Synthesis of triketide δ-lactones
In many syntheses, we obtained the final products as enantiomeric pairs. Our studies confirmed that the biological effects of the optically active substances depend on their configuration. Moreover, structural modifications of natural monoterpenoids, such as lactonization, iodolactonization, and incorporation of hydroxyl and carbonyl groups, can cause changes in their biological activities. Some of the prepared compounds were very effective antifeedants against selected insect pests. Their activities are comparable with that of the most active known antifeedant, azadirachtin [, , ].
Our interest in terpenoid lactones is inspired mainly by their activity as insect feeding deterrents; many natural antifeedants contain the lactone moiety and have isoprenoid structures [–]. However, their low concentrations in plants and their typically complex syntheses have limited the large-scale application of natural antifeedants. Therefore, in our opinion, synthetic feeding deterrents with simple structures offer better potential for practical use in insect pest population control. Thus, we have synthesized a number of terpenoid lactones by using optically active monoterpenoids as the starting materials [–, , ].
Synthetic odoriferous unsaturated Î³-lactones
Here, we present the stereoselective synthesis of racemic and enantiomeric pairs of new δ-hydroxy-γ-lactones (6a-c, 11a-c) with the p-menthane system. The lactones were obtained from racemic and enantiomerically enriched (ee = 91–98%) cis- (1a-c) and trans-piperitols (7a-c), which were synthesized from racemic piperitone as described earlier . The optically active and racemic hydroxy lactones, as well as piperitone, were examined for antifeedant activity against A. diaperinus, L. decemlineata, and M. persicae.
AB - An efficient synthetic route was developed to prepare substituted δ-lactones 1 and 2 in enantiopure forms which are potentially useful for biosynthetic studies with genetically engineered modular polyketide synthase (PKS). The key step to prepare the target epimeric lactones involves the samarium(II) iodide-mediated Reformatsky reaction.
Synthesis of New Substituted Lactones by "Click" Chemistry.
N2 - An efficient synthetic route was developed to prepare substituted δ-lactones 1 and 2 in enantiopure forms which are potentially useful for biosynthetic studies with genetically engineered modular polyketide synthase (PKS). The key step to prepare the target epimeric lactones involves the samarium(II) iodide-mediated Reformatsky reaction.
Combination of Ring-Opening Polymerization and "Click" Chemistry for the Synthesis of an Amphiphilic Tadpole-Shaped Poly(ε-Caprolactone) Grafted by PEO.
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Synthesis of a Benzolactone Collection using Click Chemistry.
In efforts toward the total syntheses of scabrolides A & B and sinulochmodin C via transannular C-H insertions, β-lactones served as the key intermediates for the synthesis of complex macrocyclic model substrates.
Lactone synthesis - Organic chemistry
An efficient synthetic route was developed to prepare substituted δ-lactones 1 and 2 in enantiopure forms which are potentially useful for biosynthetic studies with genetically engineered modular polyketide synthase (PKS). The key step to prepare the target epimeric lactones involves the samarium(II) iodide-mediated Reformatsky reaction.
Synthesis of Lactones and Lactams: Michael A. …
This synthesis features a three-step synthesis of a bicyclic β-lactone, which constitutes the key intermediate for the highly stereocontrolled introduction of the six contiguous stereogenic centers in the natural product.
Natural Lactones and Lactams. Synthesis, Occurrence …
In the total syntheses of the naturally occurring, α-glucosidase inhibitors schulzeines B & C, a readily available trichloromethyl β-lactone was used as a versatile masked surrogate for bishomoserine aldehyde, which led to a highly efficient construction of the core structures through a pivotal Pictet-Spengler condensation and a Corey-Link reaction.
Asymmetric Synthesis of Styryl-Lactones | …
Similarly to the synthesis of lactones 6a-c, we assume that the lactonization of epoxy esters 9a-c proceeds via the diols (10, ). In the case of epoxides 9a-c, nucleophilic attack at C-3’ leads to trans-diaxial diols 10 with the carboethoxymethylene group in the equatorial position.
Synthesis of γ-lactones by desymmetrization
The versatile reactivity patterns offered by β-lactones have enable chemists to utilize them as powerful synthetic vehicles in complex molecule synthesis.
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