General and operative domino Claisen-Schmidt/Henry (CS/H) reaction has been revealed to obtain highly substituted chiral decalines in good yields with excellent ees and des by using push-pull enamine catalysis.
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http://dx.doi.org/10.1039/c5ob00562k | DOI Listing |
Org Lett
December 2024
Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
We describe a concise asymmetric total synthesis of naturally occurring [5,5]-oxaspirolactone β-levantenolide through an adventitious bromo-spirocyclization reaction of a -decalin appended γ-alkylidenebutenolide. The γ-alkylidenebutenolide core was constructed through "Pd-Cu" bimetallic cascade lactonization reaction of properly functionalized enantiopure alkyne. (+)-Sclareolide was used as a chiral pool starting material to access the desired alkyne.
View Article and Find Full Text PDFNat Commun
September 2024
Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
Interest in developing separation systems for chemical entities based on crystalline molecules has provided momentum for the fabrication of synthetic porous materials showing selectivity in molecular encapsulation, such as metal-organic frameworks, covalent organic frameworks, hydrogen-bonded organic frameworks, zeolites, and macrocyclic molecular crystals. Among these, macrocyclic molecular crystals have generated renewed interest for use in separation systems. Selective encapsulation relies on the sizes, shapes, and dimensions of the pores present in the macrocyclic cavities; thus, nonmacrocyclic molecular crystals with high selectivity for molecular encapsulation via porosity-without-pore behaviors have not been studied.
View Article and Find Full Text PDFJ Org Chem
July 2024
Department of Chemistry and Biochemistry and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive MC0358, San Diego, California 92093, United States.
A simple empirical method is described that allows the assignment of absolute configurations of natural products containing chiral vicinal bromochloro (VBC) units, including the bromochloro substituted isoprenyl units present in the structures of antiproliferative halomon () and its halogen-swapped isomer -halomon () from the red alga, , and callophycols A () and B () from . The relative configurations of and , published in 2007, were incomplete: C-16 was left unassigned. It is now shown that the additivity of molar rotations, [] (herein, abbreviated [])─a consequence of van't Hoff's principle of optical superposition─could be used to deconvolute rotatory contributions, designated as [] and [] of the two remotely spaced chiral substructures within and using simple arithmetic.
View Article and Find Full Text PDFChem Sci
November 2023
Department of Chemistry and Research Center for Molecular Recognition and Synthesis, Fudan University 220 Handan Rd. Shanghai 200433 China
We report herein the collective asymmetric total synthesis of seven pentacyclic 19--clerodane diterpenoids, namely (+)-teucvin (+)-cracroson A, (+)-cracroson E, (+)-montanin A, (+)-teucvisin C, (+)-teucrin A, and (+)-2-hydroxyteuscorolide. An ytterbium-catalyzed asymmetric inverse-electron-demand Diels-Alder reaction of 4-methyl-2-pyrone with a chiral C5-substituted cyclohexa-1,3-dienol silyl ether is the key feature of the synthesis, which provides the common -decalin intermediate with five continuous stereocenters in excellent yield and stereoselectivity. From this diversifiable intermediate, the total synthesis of (+)-teucvin and (+)-2-hydroxyteuscorolide was realized in thirteen and eighteen steps, respectively.
View Article and Find Full Text PDFCommun Chem
November 2023
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
The large superfamily of labdane-related diterpenoids is defined by the cyclization of linear geranylgeranyl pyrophosphate (GGPP), catalyzed by copalyl diphosphate synthases (CPSs) to form the basic decalin core, the copalyl diphosphates (CPPs). Three stereochemically distinct CPPs have been found in plants, namely (+)-CPP, ent-CPP and syn-CPP. Here, we used X-ray crystallography and cryo-EM methods to describe different oligomeric structures of a syn-copalyl diphosphate synthase from Oryza sativa (OsCyc1), and provided a cryo-EM structure of OsCyc1 mutant in complex with the substrate GGPP.
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