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

• naphthyl substituents carrying each an alkyne moiety on the ortho position. Ring expansion of both thiophene units in 19 was then triggered by platinum catalysis to generate the corresponding thiopyrans, and finally the bromine atoms located on the latter rings were exploited for the ring closure of the

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• mechanistic studies. The reactivity of the substituted allenes towards triplet aromatic thiones was investigated. The product analysis revealed the formation of thietanes and occasionally of [4 + 2] cycloadducts (thiopyrans) generally in high overall yields. Steady-state measurements showed that electron

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland 10.3762/bjoc.14.156 Abstract Aryl and hetaryl thiochalcones react smoothly with 1,4-quinones in THF solution at 60 °C yielding the corresponding fused 4H-thiopyrans after spontaneous dehydrogenation of the

• –Alder reactions are rarely reported. However, aryl and hetaryl thioketones are known to react as ‘superdienophiles’, thereby yielding the corresponding 3,6-dihydro-2H-thiopyrans [11][12][13][14]. Despite the fact that thiochalcones exist in solution as mixtures of dimers [15][16], they enter into

• cycloaddition reactions not only as heterodienes [17][18][19], but also as heterodipolarophiles [15]. In two recent publications we reported new thia-Diels–Alder reactions of aryl, hetaryl and ferrocenyl-substituted thiochalcones with acetylenic dienophiles, which lead to the corresponding 4H-thiopyrans in a

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• evidence of the carbenoid intermediates formation. In 2010, Maguire et al. studied the enantioselective insertion of copper carbenoid derived from α-diazosulfones into C(sp3)–H bonds [10]. In this work, the authors produced cyclic sulfones (thiopyrans) 52 with high enantioselectivity by using a combination

• the carbenoid formation from (R)-48a and (R)-48b and its intramolecular insertion into C(sp3)–H bonds. Insertion of asymmetric copper carbenoid C(sp3)–H bonds to prepare thiopyrans 52. Asymmetric insertion of copper carbenoids in C(sp3)–H bonds to prepare five-membered cyclic sulfones 54. Asymmetric

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• sulfones. Keywords: dimethyl acetylenedicarboxylate (DMAD); hetero-Diels–Alder reactions; high pressure reactions; methyl propiolate; thioketones; thiopyrans; Introduction A series of recent publications evidence that, in contrast to earlier opinions, thioketones are useful building blocks for the

• examine the reactions of diverse hetaryl thioketones with both 2a and methyl propiolate (2b). Moreover, along with standard procedures, the high-pressure technique was applied. Finally, selected examples of the obtained polycyclic 2H-thiopyrans were oxidized to give the corresponding sulfones. Results and

• experiments, thiopyrans 4a,b and 5a,b were oxidized in CH2Cl2 solution at room temperature using 3.0 equivalents of mCPBA. In the case of 4a, the progress of the reaction was monitored by TLC and 1H NMR spectroscopy. The spectrum recorded after 3 h showed that along with starting materials, two new products