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

• , vinyl, ethynyl or sulphide are sufficient if a superbase such as LIDAKOR or LICKOR is used (Scheme 16) [54][55]. The reaction tends to be remarkably regioselective (in terms of the epoxide opening) and stereoselective, however, it should be treated with caution in case of allyl ethers as they can also

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation

• A. S. Antonov,
• A. F. Pozharskii,
• P. M. Tolstoy,
• A. Filarowski and
• O. V. Khoroshilova

Beilstein J. Org. Chem. 2018, 14, 2940–2948, doi:10.3762/bjoc.14.273

• rotation of the NH2+ fragment in dications. Keywords: hydrogen bond; imine; NMR; proton sponge; superbase; Introduction It is well known that the extremely high basicity of 1,8-bis(dimethylamino)naphthalene (1, DMAN; pKa = 12.1 in H2O [1][2], 18.62 in MeCN [3], 7.5 in DMSO [4]) and its derivatives

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• combination of KOH/DMSO and 2-halothioanisole forms an orange adduct, which absorbs visible-light. They propose that KOH/DMSO as a superbase can photoreduce the aryl halide, which subsequently generates an aryl radical by expelling the halide anion. Radical addition to the acetylene derivative yields a vinyl

• radical, which cyclizes to the respective sulfuranyl radical. Oxidation of this intermediate by the radical cation of the superbase closes the electron transfer cycle. Rearomatization of the benzothiophene proceeds via demethylation, accomplished by a hydroxide anion. They were able to perform the

Phosphazene-catalyzed desymmetrization of cyclohexadienones by dithiane addition

• Matthew A. Horwitz,
• Elisabetta Massolo and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2017, 13, 762–767, doi:10.3762/bjoc.13.75

• phosphazene bases in deprotonating carboxylate dithianes, we selected the commercially available achiral superbase P2-t-Bu phosphazene to initiate the ring closure (Scheme 2) [31][32]. We found that in the simplest case, with the methyl-substituted para-quinol ester (1a), the reaction was complete in 30 min

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• ], and for which the 1:1 LiTMP·2LiCl(±TMEDA)–Zn(TMP)2 composition was given [32], proved to be a ‘superbase’. Indeed, its reactivity is higher than that of the separate LiTMP and Zn(TMP)2) when used to functionalize sensitive aromatic compounds such as heterocycles [31][33][34][35][36][37][38][39][40][41

2-(1-Hydroxypropyn-2-yl)-1-vinylpyrroles: the first successful Favorsky ethynylation of pyrrolecarbaldehydes

• A. V. Ivanov,
• V. S. Shcherbakova,
• I. A. Ushakov,
• L. N. Sobenina,
• O. V. Petrova,
• A. I. Mikhaleva and
• B. A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 228–232, doi:10.3762/bjoc.11.25

• :1.6:13.6) and a temperature of 7–10 °C (Table 1), which is by ca. ten degrees higher than recommended in the patent [22], are appropriate for the efficient ethynylation of 1-vinylpyrrole-2-carbaldehydes with acetylene. As alkali metal hydroxide for the superbase composition we have chosen NaOH since

• give inferior yields of the corresponding acetylenic alcohol. In the above optimal superbase composition, ethanol was proved to be a necessary component as it homogenizes the reaction mixture and provides for the controlled decrease of the basicity [23][24]. The latter is needed to prevent the

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• in a pseudo five-component reaction via a Sonogashira–Glaser coupling sequence followed by a superbase-mediated (KOH/DMSO) cyclization in a consecutive one-pot fashion. Besides the straightforward synthesis of natural products and biologically active molecules all representatives are particularly

• ] employing the superbase system DMSO/KOH/H2O in the terminal cyclization step [33]. The same approach was applied to butadiynes that were formed by oxidative dimerization of arylalkynes with a Cu/Fe catalyst [34]. Apart from using reactive terminal alkynes as starting materials the major drawbacks of this

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• reacts with sec-butyllithium in the presence of N,N,N',N'-tetramethylethylenediamine ("TMEDA") smoothly under hydrogen/metal permutation ("metalation") as shown in Scheme 13 [72]. 4-Trifluoromethoxybiphenyl can be metalated using the Schlosser superbase LIC-KOR made by combining butyllithium (LIC) with