Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• cameroonensis. The presence of cytochalasins and cytosporones was obvious, as they constitute the taxonomic markers of the genus Diaporthe [8]. Other classes of compounds including chromones, chromanones, benzofuranones, and macrolides reported in this study, were also isolated from the genus Diaporthe [8][26

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• ]. Previous studies have shown that 2-(2-phenylethyl)chromones and sesquiterpenes are the characteristic and main bioactive components of agarwood [5][6]. Various bioactivities, including neuroactive [4], gastrointestinal modulation [7], cytotoxicity [8], antibacterial [9], antifungal, acetylcholinesterase

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• heterocycles, namely benzofurans, benzothiophenes, isocoumarins, chromones, benzopyrans, 1,2-dihydronaphthaIenes, coumarins, and coumestan including some physiologically active heterocyclic natural products like flavones [84]. In the presence of Hg(OAc)2 in acetic acid, simple cyclization of ortho-substituted

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• given combination of enone and arylboronic acid. Keywords: asymmetric reaction; boronic acid; conjugated enones; chromones; enantioselective catalysis; Michael addition; Pd complexes; Introduction The asymmetric 1,4-addition of arylboronic acids to conjugated cyclic enones and chromones is a very

• , Table 22) [51]. According to these findings, Stoltz and co-workers tested the catalytic system with a library of different chromones for the addition of various boronic acids. The substituted flavanones were obtained with moderate to good yields (36–96%) and usually very high levels of

• development of a methodology for the enantioselective addition to 2-substituted chromones [63]. The original work from the Stoltz group using pyridine-oxazolines was very successful for addition reactions to 2-unsubstituted chromones (Table 23). However, in the attempted addition reaction of phenylboronic

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• have also been employed to synthesize such chiral oxygen-containing heterocyclic compounds. Feringa’s group reported the highly regio- and enantioselective copper-catalysed direct conjugate addition of Grignard reagents to chromones and coumarins (Scheme 5) [28][29]. A variety of Grignard reagents

• , including linear and secondary alkylmagnesium reagents and various chromones and coumarins, were tolerated by the catalytic system, providing the products with a high yield and enantioselectivity. It was also demonstrated that the addition products could be used for further transformations in order to

• , it was shown that upon the treatment with an amine, this enolate produced the final chiral amide product with a good yield (82%) and ee (96%). While the methodology for the ACAs of Grignard reagents to chromones and coumarins has been established successfully, quinolones remained challenging

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

• Qiao Li,
• Chen Zhuang,
• Donghua Wang,
• Wei Zhang,
• Rongxuan Jia,
• Fengxia Sun,
• Yilin Zhang and
• Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

• highly efficient method for the synthesis of this privileged class of heterocycles. For example, Kim and co-workers reported that chromones could be prepared via a Pd(II)-catalyzed [55][56][57] dehydrogenation of chromanone derivatives at 100 °C in DMSO (Scheme 1a) [58]. The synthesis of chromones could

• also be realized by DDQ-mediated dehydrogenation of chromanones under heating in dioxane (Scheme 1b) [3][59][60]. In 2005, Yang and co-workers reported that chromones could be formed by microwave irradiation of the corresponding chromanone reactants and N-bromosuccinimide (NBS) in the presence of a

• catalytic amount of azobis(isobutyronitrile) (AIBN) in CCl4 (Scheme 1c) [61][62]. In 2002, Nicolaou and co-workers found that ortho-iodoxybenzoic acid (IBX) could also effectively dehydrogenate chromanones to chromones (Scheme 1d, method 1) [63]. Moreover, active MnO2 was also found useful in the oxidative

Microfluidic light-driven synthesis of tetracyclic molecular architectures

• Javier Mateos,
• Nicholas Meneghini,
• Marcella Bonchio,
• Nadia Marino,
• Tommaso Carofiglio,
• Xavier Companyó and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2018, 14, 2418–2424, doi:10.3762/bjoc.14.219

• synthetic method for the direct assembly of highly functionalized tetracyclic pharmacophoric cores. Coumarins and chromones undergo diastereoselective [4 + 2] cycloaddition reactions with light-generated photoenol intermediates. The reactions occur by aid of a microfluidic photoreactor (MFP) in high yield

• suited for a broad range of coumarins 2 and chromones 3, used as precursors for the direct generation of the tetracyclic scaffold 4 and 5, with high synthetic performances (up to >98% yield) and complete diastereocontrol (>20:1). Additionally, manipulations of the naphthochromenone scaffold 4 give access

Transition-metal-free synthesis of 3-sulfenylated chromones via KIO₃-catalyzed radical C(sp²)–H sulfenylation

• Yanhui Guo,
• Shanshan Zhong,
• Li Wei and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2017, 13, 2017–2022, doi:10.3762/bjoc.13.199

• chromones via domino chromone ring construction and C(sp2)–H bond sulfenylation have been achieved under transition-metal-free conditions by using KIO3 as the only catalyst. Keywords: C–H sulfenylation; chromones; domino reaction; free-radical; transition-metal-free; Introduction The C–S bond-forming

• the synthesis of many useful organic compounds elaborated with sulfenyl groups. For example, the 3-sulfenylated chromones, a class of useful organic molecules with important biological profiles [28][29][30][31] and extensive application in synthetic chemistry [32][33][34][35][36][37], have been

• readily synthesized with several different transition-metal-free C–H cross-coupling approaches. Zhou and co-workers reported the NH4I-promoted synthesis of 3-sulfenylated chromones via the direct chromone C–H sulfenylation by using different sulfur sources (A, Scheme 1) [38][39]. Recently, our continuous

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• have been reported to be C-glycosylated: flavones, xanthones, chromones, anthrones, and gallic acids. Several corresponding plant C-GT have been cloned, expressed and characterized, from several crops including maize [35], rice [36][37], wheat [36], buckwheat [38] and other plants such as Arabidopsis

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• –Hilman condensation, and a final deoxygenation. The deoxygenation is assumed to be induced by carbon monoxide resulting from the thermal decomposition of the dimethylformamide solvent. Keywords: chromones; domino reactions; Michael additions; multicomponent reactions; transfer hydrogenation

• ; Introduction Chromones are widely present in nature, especially in the plant kingdom, and a wide variety of useful biological properties are associated with them [1][2]. Chromone derivatives act as effective tyrosine and protein kinase C inhibitors [3] and display antifungal [4][5], antimycobacterial [6

• relatively few methods, which allow the preparation of hybrid structures containing chromone derivatives attached to other heterocyclic systems due to the lack of suitable building blocks. In order to come up with such building blocks, we planned the preparation of chromones containing a β-enaminone

Regioselective 1,4-trifluoromethylation of α,β-unsaturated ketones via a S-(trifluoromethyl)diphenylsulfonium salts/copper system

• Satoshi Okusu,
• Yutaka Sugita,
• Etsuko Tokunaga and
• Norio Shibata

Beilstein J. Org. Chem. 2013, 9, 2189–2193, doi:10.3762/bjoc.9.257

• –Hillman adducts (via SN2’ [16] or successive SN2’/SN2’ mode [17]). Sevenard and co-workers reported the nucleophilic 1,4-trifluoromethylation to chromones, coumarins and cyclohex-2-enone using the Ruppert–Prakash reagent, which was achieved by blocking the carbonyl moiety of the substrates with a bulky

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• chromones. The synthetic methods in the literature will be compared and contrasted in terms of their generality, selectivity and percentage yields. Review Chromane derivatives from the reaction of salicylaldehyde with enolates derived from ketones The reaction of salicylaldehyde (5) and enolates derived

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• ). The reaction of hydroxylamine with 3-(4-phenyl-1,2,4-triazol-3-yl)chromones 173 has been reported to give the 2-aminochromones 174. The 2-aminochromones 174 undergo ring transformation to afford the 5-aminopyrazoles 175 but only upon prolonged heating with hydrazine hydrate in high boiling alcohols (2

Synthesis of spiropyrans: H-abstractions in 3-cycloalkenyloxybenzopyrans

• Satish C. Gupta,
• Mandeep Thakur,
• Somesh Sharma,
• Urmila Berar,
• Surinder Berar and
• Ramesh C. Kamboj

Beilstein J. Org. Chem. 2007, 3, No. 14, doi:10.1186/1860-5397-3-14

• ions could very well be the result of rDA fragmentation of 5c and 6c. In the mass spectrum of 6c, the base peak was at m/z 327 (M+ -CHO). The other chromones 1a, 1b and 1d on photoirradiation rearranged to spirocyclic pyranopyrones 5a, 5b, 5d and 6a, 6b, 6d. The photoirradiation of 2a, 2b and 2c

• yielded 7a, 7b, 7c only and no photoproducts similar to 5 (R = CH3) could be isolated although the 1H NMR of the crude photolysate of 2b did show the presence of 5b (R = CH3) in small proportions. These photoconversions of the cycloalkenyloxy chromones (1a, 1b, 1c, 1d, 2a, 2b and 2c) to pyronospiropyrans