Oxetanes: formation, reactivity and total syntheses of natural products

• Peter Gabko,
• Martin Kalník and
• Maroš Bella

Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101

• loadings were necessary for ortho-substituted phenyls. Control experiments and DFT calculations revealed that the oxetane ring is formed before the tetrahydrofuran in the domino process. In 2023, Shigehisa and co-workers published a new cycloisomerisation strategy for the construction of oxetane rings from

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• and Suzuki–Miyaura cross-coupling reactions followed by Brønsted acid-mediated cycloisomerisation. The developed methodology tolerates various functional groups and leads to moderate up to quantitative yields of the final products. The impact of different functional groups on the optical properties

• of palladium-catalysed Sonogashira–Hagihara and Suzuki–Miyaura cross-coupling reactions (Scheme 1). The final cyclisation step is accomplished by an acid-mediated cycloisomerisation. The synthesis of starting materials 4 was carried out by our previously reported protocol [65]. While compounds 4a–f

• are known compounds, the synthesis of derivatives 4g–i has not been previously reported (Scheme 2). Yields were generally lower in case of the presence of electron-withdrawing substituents. Subsequently, the cyclisation of 4a–i to 5a–i by acid-mediated cycloisomerisation was studied. In our first

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

• Takashi Go,
• Akane Morimatsu,
• Hiroaki Wasada,
• Genzoh Tanabe,
• Osamu Muraoka,
• Yoshiharu Sawada and
• Mitsuhiro Yoshimatsu

Beilstein J. Org. Chem. 2018, 14, 2722–2729, doi:10.3762/bjoc.14.250

• radical cyclisations [28] and the 1,7-electrocyclisation of azomethine ylides or ring expansion sequences [29]), most of these approaches are ineffective for synthesising pyrrolo[3,2-c]azepines. Recently, Echavarren and Beller reported a novel Au- or Pt-catalysed cycloisomerisation reaction of pyrrole-2

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• reduction, and ring enlargement. One isomeric dialkyne additionally allows for the isolation of a pentacyclic compound lacking the ring enlargement step, which we have proposed as a potential intermediate in the catalytic cycle. Keywords: alkynes; camphor derivatives; catalysis; cycloisomerisation

• , leading to pure dialkynes with a well-defined substitution pattern. The reactivity of a pair of isomers containing a phenyl and a pentyl group attached to the triple bonds towards cycloisomerisation induced by Pt(II) catalysis was studied. The expected annulation–sulphur reduction–ring enlargement cascade

• derivatives by protection of the 3-oxo group as an acetal. Selective synthesis of 2-alkynyl derivatives by protection of the 3-oxo group as an imine. Synthesis of the bis-alkynyl derivatives bearing different alkyne substituents and their platinum-catalysed cycloisomerisation. Compounds 21a and 22a: R1 = Ph

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η¹-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

• Rajendra K. Jangid,
• Nidhi Sogani,
• Neelima Gupta,
• Raj K. Bansal,
• Moritz von Hopffgarten and
• Gernot Frenking

Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40

• experimentally the InCl3-catalyzed cycloisomerisation of 1,6-enynes and demonstrated InCl2+ to be the actual catalytic species participating in the reaction. In this context, it has been emphasized that identifying the real catalytic species may be very challenging, because in many cases impurities in the

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

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

• pyrroles 173 by gold-catalyzed ring expansion of alkynyl aziridines 172 [79]. In this study a combination of Ph3PAuCl and AgOTs generates a catalyst system that provides clean cycloisomerisation reactions. Similarly, N-Phth pyrrroles 175 are obtained via gold-catalyzed cycloisomerization of N-Phth alkynyl

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• Paul W. Davies Nicolas Martin Neil Spencer School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom 10.3762/bjoc.7.96 Abstract Isotopic labelling studies were performed to probe a proposed 1,2-aryl shift in the gold-catalysed cycloisomerisation of alkynyl

• - and deuterium-labelled substrates. Keywords: 1,2-aryl shift; cycloisomerisation; gold; isotopic labelling; pyrrole; skeletal rearrangement; Introduction Gold-catalysed cycloisomerisation reactions have emerged as powerful methods to construct a diverse array of hetero- and carbocyclic motifs under

• reaction conditions resulted in selective cycloisomerisation to produce either the 2,5-disubstituted pyrrole 2 or the skeletally rearranged 2,4-disubstituted pyrrole 3 (Scheme 1) [18]. The nature of both the solvent, and the counter ion to the cationic gold catalyst, proved crucial to the reaction outcome

Halide exchanged Hoveyda-type complexes in olefin metathesis

• Julia Wappel,
• César A. Urbina-Blanco,
• Mudassar Abbas,
• Jörg H. Albering,
• Robert Saf,
• Steven P. Nolan and
• Christian Slugovc

Beilstein J. Org. Chem. 2010, 6, 1091–1098, doi:10.3762/bjoc.6.125

• catalytic performance of the complexes in ring opening metathesis polymerisation, ring closing metathesis, enyne cycloisomerisation and cross metathesis reactions. Keywords: cross metathesis; olefin metathesis; RCM; ROMP; ruthenium; Introduction Since the pioneering reports on the utilisation of N

• before the remaining monomer is completely consumed. RCM, enyne cycloisomerisation and cross metathesis Catalytic activities of 1, 2 and 3 were then evaluated in RCM of diethyl diallylmalonate (7). The reaction progress is shown in Figure 6 (for details see Table 3). While 1 and 2 perform equally, 3 is

• concentrated on further elucidating the catalytic potential of 3 in RCM, enyne cycloisomerisation and cross metathesis (CM). Benchmark substrates were selected according to protocols for testing of metathesis catalysts [33]. Substrates with low steric hindrance (Table 3, Entry 1 and 3) were transformed with

The use of silicon- based tethers for the Pauson- Khand reaction

• Adrian P. Dobbs,
• Ian J. Miller and
• Saša Martinović

Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21

• . Saigo reported that the attempted P-K cyclisation of a variety of 3-sila-1,7-enynes underwent cycloisomerisation instead of the cycloaddition (Scheme 1).[7] Saigo's work showed that this cycloisomersiation was only applicable to 3-sila-1,7-enynes and any other chain length would undergo decomposition

• obtained, only the cycloisomerisation products predicted by Saigo.[7] Repeating the reactions under 1 atm pressure of carbon monoxide also gave only the isomerisation products, albeit in higher yields and more rapidly. In every example, the main product, accounting for the bulk of the mass balance, were

• of the silyl ether formed, figures in brackets the product recovered from the Pauson-Khand reaction. Possible structure of THF-oxidation/insertion product. Saigo's cycloisomerisation reaction under Pauson-Khand conditions. Pauson-Khand reaction and tether-cleavage in wet acetonitrile. Silyl-tethered