Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• conversion in situ, triggered by thermal activation, photoirradiation or redox control. Beside well-established reactions involving the elimination of carbon-based small molecules, i.e., retro-Diels–Alder and decarbonylation processes, the late-stage extrusion of chalcogen fragments has emerged as a highly

• π-CPCs relies on the extrusion of carbon monoxide (CO) from soluble precursors incorporating bridging ketone fragment(s). In contrast with the thermal activation required in retro-Diels–Alder reactions, photoirradiation of α-diketones triggers a Strating–Zwanenburg decarbonylation leading to the

• precursor, recovery of the target π-CPC is possible via a cheletropic decarbonylation step upon photolysis or thermolysis (Scheme 1, bottom right). This dual activation mode has led to the solid-state formation, on a preparative scale, of higher acenes up to nonacene [28][29][30][31][32][33] and

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• -situ imine formation is currently impossible with catalytic or stoichiometric amounts of amine due to decarbonylation of furfural under the reaction conditions [21]. We thus present here an adaptation of our Ru(0)-catalyzed C3-alkylation strategy of furfural derivatives to a continuous flow system

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• solutions Xu et al. used energy-rich carbon precursors for the spherical carbon preparation via ultrasonic spray pyrolysis. Lithium, sodium or potassium propiolates are one class of such energy rich materials and exhibit leaving groups such as CO, CO2 or C2H2 eliminated by decarbonylation or decarboxylation

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• 43 to generate 44. The isotope exchange was explored by using [18F]-TBA in DMF at 130 °C for 10 min to give [18F]-44. Decarbonylation of 44 was achieved by treatment with Rh(PPh3)3Cl to afford 45 and the subsequent removal of protecting groups gave 46. Conventional reactions yielded the desired

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• decarbonylation of the ruthenium hydride 16. In 2015, Cazin and co-workers showed that the detrimental effect of H2O also occurs with the more innovative catalysts Caz-I, Ind-II and HG-II (Table 1) [32]. The authors performed the RCM of the challenging substrate 17 in toluene at 110 °C, reporting excellent yields

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• palladium-catalyzed reaction that results in phenanthrene derivatives using aryl iodides, ortho-bromobenzoyl chlorides and norbornadiene in one pot. This dramatic transformation undergoes ortho-C–H activation, decarbonylation and subsequent a retro-Diels–Alder process. Pleasantly, this protocol has a wider

Synthesis of pyrimido[1,6-a]quinoxalines via intermolecular trapping of thermally generated acyl(quinoxalin-2-yl)ketenes by Schiff bases

• Svetlana O. Kasatkina,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Ivan G. Mokrushin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2018, 14, 1734–1742, doi:10.3762/bjoc.14.147

• Svetlana O. Kasatkina Ekaterina E. Stepanova Maksim V. Dmitriev Ivan G. Mokrushin Andrey N. Maslivets Department of Chemistry, Perm State University, ul. Bukireva 15, Perm 614990, Russian Federation 10.3762/bjoc.14.147 Abstract Acyl(quinoxalin-2-yl)ketenes generated by thermal decarbonylation of

• the thermal decarbonylation (thermolysis) of five-membered 2,3-dioxoheterocycles having a quinoxaline fragment. Currently, three types of such precursors are known: 5-aryl-4-quinoxalin-2-ylfuran-2,3-diones I [21], 3-aroyl-4-arylpyrrolo[1,2-a]quinoxaline-1,2-diones II [55], and 3-acylpyrrolo[1,2-a

• ]. Under these circumstances precursors III generating ketenes V seemed to be the only suitable candidates for the development of a strategy towards pyrimido[1,6-a]quinoxalines. First, we studied the decarbonylation of precursors III – 3-acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones (PQTs, 1a–h) by

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• oxidized to 1-ethynylbenzotropone 150 in situ, the etheric compound 152 was obtained from the reaction of 1,2-addition product 151 with HCl (Scheme 25). c. Decarbonylation of 4,5-benzotropone (11): The mechanism for the neutral and radical-cationic decarbonylation of tropone and benzannulated tropones was

• the thermal and electron impact-induced decarbonylation reaction of 12 (Scheme 36) [131]. Tajiri’s group reported the resolution and determination of the kinetic parameters of the optically active 2,3-benzotropone(tricarbonyl)iron complex 221 using high-performance liquid chromatography (HPLC) and

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• aromatic iodide. Additionally, the intermediate III is also unstable and decomposes to intermediate IV in the presence of water. And DBU is regenerated after the elimination of HF and decarbonylation. Then, the group of Zhang [22] from GlaxoSmithKline designed trimethylsilyl chlorodifluoroacetate (TCDA) as

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• ) followed by chlorination gave chlorodiketone 147. The latter was then treated with sodium carbonate in boiling xylene to afford cyclopentenone 148, presumably via decarbonylation of a cyclopropanone intermediate. Addition of the lithium anion of chiral phosphonamide 64a at low temperature produced adduct

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• amounts of decarbonylated analogues were detected when the reaction was performed at 120 °C with the nitrobenzaldehyde derivatives (Table 2, entries 4 and 5). The aldehyde decarbonylation reaction in Pd catalytic systems has recently been reported in the literature [58][59]. High conversion and

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• reported by J. F. Hartwig [45], J. M. Shreeve [46] and further investigated and generalized to both open-chain and cyclic α-fluoroketones by F. L. Qing [47][48]. However, further decarbonylation to the monofluoromethyl group proved difficult. 1.2 Copper catalysis Recently a copper-catalyzed

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• ) [36]. Cheap and readily available malic acid (1.57) undergoes self-condensation to yield coumalic acid under strongly acidic dehydrating conditions [37][38][39][40]. The mechanism is believed to progress by initial dehydration/decarbonylation of malic acid to give an aldehyde acid enol 1.60 which then

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• ) alkoxycarbene. The complex could be generated stoichiometrically when norbornene was utilized as a hydrogen acceptor. The reaction was shown to be general for several methyl ethers and tetrahydrofuran, but other ethers were prone to 1,2-dehydrogenation or decarbonylation [88][89] The use of methyl amines as

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

• Rick C. White,
• Benny E. Arney Jr. and
• Heiko Ihmels

Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134

• decarbonylation results in an alkyl radical. The latter reaction yields bibenzyl (4) and toluene (7) in the photoreaction of 8. It should be noted that the diradical BR2 may be formed also upon photoinduced ring-opening reaction of an intermediate oxirane 2a, which is not detectable in the reaction mixture

Synthesis of fused tricyclic amines unsubstituted at the ring-junction positions by a cascade condensation, cyclization, cycloaddition then decarbonylation strategy

• Iain Coldham,
• Adam J. M. Burrell,
• Hélène D. S. Guerrand,
• Luke Watson,
• Nathaniel G. Martin and
• Niall Oram

Beilstein J. Org. Chem. 2012, 8, 107–111, doi:10.3762/bjoc.8.11

• positions (such as compound 2, R = H, or other ring sizes) [22]. This paper outlines an approach to such targets using a substituent (to block side reactions) which can then be removed by decarbonylation [23]. Results and Discussion Preparation of the aldehyde substrates We decided to incorporate a one

• protons, was a decarbonylation and this type of reaction is known using Wilkinson’s catalyst [25]. We were disappointed to find that attempts to conduct this decarbonylation using aldehyde 16 and [Rh(PPh3)3Cl] resulted only in decomposition. As an aside, we were interested in using the products of this

• to the core of the alkaloids meloscine and scandine, which contains the same fused tricyclic ring system. The use of glycine to form a ‘non-stabilized’ ylide had led to the desired cycloadduct 14, although subsequent decarbonylation had not been successful using aldehyde 16 (Scheme 5). Despite this

One-pot four-component synthesis of pyrimidyl and pyrazolyl substituted azulenes by glyoxylation–decarbonylative alkynylation–cyclocondensation sequences

• Charlotte F. Gers,
• Julia Rosellen,
• Eugen Merkul and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1173–1181, doi:10.3762/bjoc.7.136

• - and pyrazolylazulenes through the use of glyoxylation–decarbonylative alkynylation–cyclocondensation sequences starting from azulene or guaiazulene as substrates, gives rise to the formation of the target compounds in moderate to good yields. Keywords: azulenes; catalysis; decarbonylation

• proceed in 3-position with both reagents, yet with lower reactivity, and its conversion was found to be incomplete even after 2 h. In addition, the formation of side products [51] and decarbonylation [52] was observed, presumably caused by the steric hindrance of the methyl group in 4-position. Encouraged

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• results in their decarbonylation (or desulfonation in the case of CF3SO2SR) with the production of CF3• radicals, which then react with diaryl- or dialkyl disulfides (Scheme 58). The formation of aryl trifluoromethyl sulfides from thioesters of trifluoroacetic acid occurs in rather better yields (30–40

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• synthesis. Results and Discussion Type of MnO2 used for alkyne deprotection The original paper on the oxidation-decarbonylation of HOM-protected alkynes [60][61] through treatment with MnO2 and powdered KOH does not contain any details about the type of MnO2. We applied this method to the synthesis of

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• and C3 oxidation. In an attempt to conclude the synthesis of FR-900482, substrate 93a was subjected to decarbonylation conditions, using 2.2 equivalents of Wilkinson’s catalyst, (PPh3)3RhCl, to give the corresponding decarbonylated product 93b with retention of configuration of the C10 side chain