Ring contraction and ring expansion reactions in terpenoid biosynthesis and their application to total synthesis

• Nicolas Kratena,
• Nicolas Heinzig and
• Peter Gärtner

Beilstein J. Org. Chem. 2026, 22, 289–343, doi:10.3762/bjoc.22.21

• carbaldehyde product atheronal B (113) with a contracted 5-membered B-ring. The rearranged triterpenoid neoabiestrine F (115), corresponds to a small family of C-ring-contracted spirocyclic terpenoids which are suspected to originate from a lanostane precursor, such as 114 (see Scheme 28B) [163][164][165]. By

• epoxidation of the 8,9-double bond present in a putative oxidised lanostane precursor 132. Meinwald (or semi-pinacol) rearrangement of epoxide 132a would then build up the 6/5/6-spiro system 132b for rings A, B and C. The final product is obtained following an oxidation at C-17, multiple 1,2-methyl shifts

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• Chemical exploration of solid-state cultures of the polypore Fomitopsis carnea afforded two new C31 lanostane-type triterpenoid glycosides, forpiniosides B (1) and C (2) together with two known derivatives, namely 3-epipachymic acid (3) and (3α,25S)-3-O-malonyl-23-oxolanost-8,24(31)-dien-26-oic acid (4

• against Staphylococcus aureus and Bacillus subtilis at MIC values comparable to gentamycin and oxytetracycline (positive controls), respectively. Keywords: antimicrobial activity; Fomitopsis carnea; lanostane glycosides; Polyporales; Introduction Great success was realized on antibiotic discovery

• well-known profuse production of bioactive molecules, Basidiomycota have already been proven to be a valuable source for new anti-infectives [4]. These include a myriad of triterpenoids which have been resourceful in the discovery of potent antimicrobials [5]. Specifically, lanostane triterpenoids are

Lanostane- and cycloartane-type triterpenoids from Abies balsamea oleoresin

• Serge Lavoie,
• Charles Gauthier,
• Jean Legault,
• Sylvain Mercier,
• Vakhtang Mshvildadze and
• André Pichette

Beilstein J. Org. Chem. 2013, 9, 1333–1339, doi:10.3762/bjoc.9.150

• -lanostane triterpenoids 1–3, one new cycloartane triterpenoid 4 along with fourteen known terpenoids. Structure determinations were based on extensive 1D/2D NMR, IR and MS spectroscopic analyses, and comparison with literature data. The isolated compounds were evaluated in vitro for their cytotoxicity

• ; lanostane; oleoresin; triterpenoids; Introduction The genus Abies (Pinaceae) comprises 46 species of evergreen conifers [1]. Most of them are found in temperate and boreal regions of the northern hemisphere. The first phytochemical investigation of Abies species was undertaken 75 years ago by Takahashi [2

• tetraterpenoids from the cortical oleoresin of the tree bark, featuring an unprecedented C40 scaffold [6]. Herein, we describe the further phytochemical study of A. balsamea oleoresin, which led to the isolation and structure elucidation of three 3,4-seco-lanostane-type triterpenoids 1–3, one cycloartane-type