Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones

• Ashutosh Nath,
• John Mark Awad and
• Wei Zhang

Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92

• (IMDA), and dehydrative re-aromatization reactions for the synthesis of imidazopyridine-fused isoquinolinones is developed. Gaussian computation analysis on the effect of the substitution groups for the IMDA reaction is performed to understand the reaction mechanism. Keywords: Groebke–Blackburn

• –Bienaymé (GBB); imidazopyridine; intramolecular Diels–Alder (IMDA); isoquinolinone; multicomponent reaction (MCR); re-aromatization; Introduction Multicomponent reactions (MCRs) have intrinsic green chemistry advantages of synthetic efficiency and operational simplicity. Performing post-condensational

• compounds [18]. Presented in this paper is a new synthetic route involving GBB, N-acylation and IMDA reactions for making intermediate III followed by dehydrative re-aromatization to give imidazopyridine-fused isoquinolinones C (Scheme 1C). Results and Discussion Following the reported procedures [10], the

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• ester 10, regenerating pyridine 137 while forming alkyl radical 12, CO2 and phthalimide–B(pin) adduct 139. Subsequently, radical–radical coupling between 12 and one equivalent of 138 affords dihydropyridine 140, which upon re-aromatization, facilitated by ZnCl2 acting as a Lewis acid, yields product 141

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• ether moiety. The best result was obtained when phenol 101 was subjected to anodic oxidation, leading to the formation of spiro-dimer 102 in 61% yield. Protection of the alcohol using TBSOTf followed by cyclic ether cleavage and re-aromatization gave compound 104. Subsequent dehalogenation followed by

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• ., the 2-thienyl derivative 13.2) afforded vinyl radical 13.5·. The final intramolecular cyclization of 13.5· and re-aromatization smoothly yielded the desired polyheteroaromatic derivative (see the case of 13.6; 84% yield). Interestingly, all the obtained scaffolds bear two heteroatoms in close

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K₂CO₃/n-Bu₄PBr in water

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati and
• Gregor Schnakenburg

Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71

• makes a hydrogen bond interaction with the NH of the 5-methoxyindole (1a) and form the adduct B. This interaction assists 1a reacting with an electrophilic ketone (2a) to form the intermediate D via C–C bond formation (C). Re-aromatization of D generates E, which then protonates to form the desired

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

• Jürgen Krauß,
• Monika Klimt,
• Markus Luber,
• Peter Mayer and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

• ][22]. For benzanilides Tu [21] proposed a mechanism involving protonation of the amide oxygen, followed by 1,3 proton shift to the ring carbon next to the amide carbonyl group, followed by elimination of protonated phenyl isocyanate under re-aromatization. For the pyrrole derived substrate

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• reactivity analogous to aldonitrones, which enables their conversion via [3 + 2]-cycloadditions with dipolarophiles such as activated ethylenes [8][9], activated acetylenes [10][11] or isocyanates [11][12]. The initially formed [3 + 2]-cycloadducts undergo spontaneous secondary conversions leading to re

• -aromatization of the imidazole ring. The same mechanism governs sulfur-transfer reactions with cycloaliphatic thioketones yielding the corresponding imidazole-2-thiones [13]. The isomerization of N-oxides 1 into the corresponding imidazol-2-ones can be easily performed by treatment with acetic anhydride at room

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• and the aldehyde yields a Schiff base and then the latter reacts with 2-naphthol in the second nucleophilic addition step. The other theory assumes the formation of an ortho-quinone methide (o-QM) intermediate by the reaction of 2-naphthol and benzaldehyde. Re-aromatization, the driving force of the

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• described for the biogenesis of (S)-reticuline (101) (compare Scheme 11). A de-aromatizing spirocyclization of 121 leads to (R)-orientalinone (122), which, after reduction of the ketone to the secondary alcohol 123, undergoes a [1,2]-alkyl migration with concomitant loss of water. Re-aromatization and

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

• Maurizio Fagnoni,
• Stefano Protti,
• Davide Ravelli and
• Angelo Albini

Beilstein J. Org. Chem. 2013, 9, 800–808, doi:10.3762/bjoc.9.91

• silyl, stannyl, t-Bu group or a hydrogen [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]), unimolecular fragmentation was possible and gave neutral alkyl radicals (D•) with a reasonable (0.1 or higher) quantum yield (Scheme 1, step b) [5]. Addition to the aromatic radical anion and re

• -aromatization gave an alkylated aromatic (A–D, path c → d), while trapping of the radical by an electron-withdrawing substituted alkene T (step e) [28][29] followed by BET from the radical anion (step f) of the acceptor (that was thus recovered) led to photocatalyzed alkylation of the alkene [5][30][31]. Both

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• indole. Further intramolecular nucleophilic attack of the phenyl group on the carbene carbon center, followed by a re-aromatization step and subsequent protodemetalation, affords 248 as the final product. Treatment of N-tethered 2,3-butadienyl-1H-indole 249 with di-tert-butyl(o-biphenyl)phosphine and

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• completely new reaction Sakamoto has proposed a mechanism involving a ζ-hydrogen abstraction to form a biradical intermediate (Scheme 35, E). The resulting biradical cyclizes to form the spiro compound F upon recombination of the biradical. Re-aromatization affords the carboxylate G, which further attacks

• can take place to form a spiro compound; further re-aromatization to form the enol, lactolization and cyclization explains the formation of the benzoxepine structure [101]. Griesbeck et al. reported the formation of benzoxepines from the benzophenone analogue upon irradiation at slightly lower

• UV absorption band at 380 nm was observed. This absorption band fits well with TD-DFT calculations. He proposes that re-aromatization of this intermediate takes place via a zwitterionic species or through a proton catalyzed pathway. We recently found in our laboratories that the intramolecular