When subjected to the conditions of a Semmler-Wolff/Schroeter aromatization, the oximes of 4-benzyl-substituted tetralones undergo an electrophilic aromatic substitution reaction to form tetracyclic frameworks.
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http://dx.doi.org/10.1021/ol2012204 | DOI Listing |
Molecules
January 2025
Department of Chemistry, Acadia University, Wolfville, NS B4P 2R6, Canada.
A concise, transition metal-free four-step synthetic pathway has been developed for the synthesis of tetracyclic heterosteroidal compounds, 14-aza-12-oxasteroids, starting from readily available 2-naphthol analogues. After conversion of 2-naphthols to 2-naphthylamines by the Bucherer reaction, subsequent selective C-acetylation was achieved via the Sugasawa reaction and reduction of the acetyl group using borohydride, which resulted into the corresponding amino-alcohols. The naphthalene-based amino-alcohols underwent double dehydrations and double intramolecular cyclization with oxo-acids leading to one-pot formation of a C-N bond, a C-O bond and an amide bond in tandem, to generate two additional rings completing the steroidal framework.
View Article and Find Full Text PDFJ Org Chem
January 2025
School of Medicine, Shanghai University, 99 Shangda Road, BaoShan District, Shanghai 200444, China.
Uncommon diterpenoids with diverse frameworks, including one unexpected iodinated oxa-6/6/6/6-tetracyclic diterpene () and its monobrominated 6/6/6-tricyclic analogue () and one novel isodolastane-type diterpene featuring an unusual aromatic 5/7/6-tricyclic ring system () as well as a related known dolastane-type diterpenoid (), were isolated from the South China Sea sponge . Their structures, including absolute configurations, were established by extensive spectroscopic data analysis, X-ray diffraction analysis, and quantum mechanical-nuclear magnetic resonance and time-dependent density functional theory/electronic circular dichroism calculations. A plausible biosynthetic pathway of new compounds - was proposed.
View Article and Find Full Text PDFNat Commun
January 2025
State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, Gansu, PR China.
Artatrovirenols A and B are two newly isolated sesquiterpenoids with a complex caged framework. We report herein a concise synthesis of artatrovirenols A and B in 9 and 8 steps, respectively. The complex caged tetracycle is rapidly constructed from a known planar guaiane-type precursor through a bioinspired intramolecular [4 + 2] cyclization to firstly access artatrovirenol B, which is further transformed into artatrovirenol A through a biomimetic epoxidation-mediated lactonization reaction.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
State Key Laboratory of Applied Organic Chemistry, College of Chemistry and chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China.
A bioinspired Lewis acid-catalyzed epoxypolyene cyclization was developed to construct the tetracyclic framework containing a bicyclo[3.3.1]nonane core and seven chiral centers.
View Article and Find Full Text PDFOrg Lett
October 2024
Department of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020 Innsbruck, Austria.
meroterpenoids are fungal derived hybrid natural product class containing a 1,2,4-trisubstituted benzene ring and a polycyclic terpenoid part. The representatives applanatumol E, H and I, lingzhilactone B, and meroapplanin B share the same bicyclic lactone moiety connected to the arene. Employing photo-Fries rearrangements as the key step enabled a general entry to these natural products.
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