Synthesis of naturally occurring tropones and tropolones

Abstract

Tropones and tropolones are an important class of seven-membered non-benzenoid aromatic compounds. They can be prepared directly by oxidation of seven-membered rings. They can also be derived from cyclization or cycloaddition of appropriate precursors followed by elimination or rearrangement. This review discusses the types of naturally occurring tropones and tropolones and outlines important methods developed for the synthesis of tropone and tropolone natural products.

Efficacy and cytotoxicity in cell culture of novel α-hydroxytropolone inhibitors of hepatitis B virus ribonuclease H

“…1) (Liu et al, 2014). To date, about 200 naturally occurring tropolones have been identified (Bentley, 2008; Zhao, 2007).…”

“…To date, about 200 naturally occurring tropolones have been identified (Bentley, 2008; Zhao, 2007). Most troponoids were isolated from plants and fungi, but methods have been developed to synthesize them (reviewed in (Liu et al, 2014)), including the α-hydroxytropolones (reviewed in (Meck et al, 2014)). Troponoids have powerful antibacterial and antifungal activities (Baillie et al, 1950; Zhao, 2007).…”

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2014

“…Specific compounds or compound classes represented include: (1) tetrahydropyrans [53]; (2) cyclopentenones [54]; (3) 3,4,5-trisubstituted isoxazolines [55]; (4) carbocyclic nucleosides [56]; (5) lycopodium alkaloids [57,58]; (6) cyclic hydrazines and azo compounds [59]; (7) tropone and tropolone natural products [60]; (8) seven-membered ring natural products [61]; [62]; (9) tetrahydroisoquinoline-3-carboxylic acid derivatives [63]; (10) chalcones and their heterocyclic derivatives [64]; (11) marine-derived cyclic ethers [65]; (12) pericosine and related marinederived carbasugar natural products [66]; (13) carbohydrate derived macrocyclic compounds [67]; (14) neurotrophic natural products [68]; (15) isodon diterpenes [69]; (16) non-isoprenoid polyene natural products [70]; (17) heterophosphacyclanes [71]; (18) chlorosulfolipids [72]; (19) seven-membered ring sulfur heterocycles; (20) organic cage compounds [73]; (21) presilphiperfolanols [74]; (22) pleuromutilin [75]; (23) hyperforin [76]; (24)…”

Construction of 2,3,4,7‐Tetrahydro‐1,2,4,5‐oxatriazepines via [4+3] Cycloadditions of α‐Halogeno Hydrazones with Nitrones

“…[1] Theg reat challenges with the construction of seven-membered rings mainly originate from the enthalpic and entropic factorsa nd non-bondingi nteractions in the transitions tates. [2] Theg eneral methods to construct seven-membered rings include [4+ +3] [3] and [5+ +2] [4] cycloadditons as well as ring-closing metathesis (RCM).…”