Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• -methanides (thiocarbonyl ylides) with electron-deficient ethylenic dipolarophiles. This method was extensively developed by Huisgen and co-workers in the 1980s [3][4][5]. In the course of these studies, a non-orthodox stepwise mechanism of the 1,3-dipolar cycloaddition was established by experiments

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

• Jury J. Medvedev,
• Ilya V. Efimov,
• Yuri M. Shafran,
• Vitaliy V. Suslonov,
• Vasiliy A. Bakulev and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253

• groups [23][27][28], C=C double [24][25][26], or C≡C triple [29][30][31][32] bonds in the structure of the initial molecule (Scheme 1). Intermolecular reaction of metal carbenes with thioamides usually generates thiocarbonyl ylides which leads for example to enaminones [14][33][34][35] or, in the

• reaction of diazocarbonyl compounds with α-cyanothioacetamides would first of all affect the electron-rich sulfur atom of the C=S group, leading to the generation of intermediate thiocarbonyl ylides, which would further react intramolecularly with the cyano group to produce a heterocyclic structure. One

• produce thiophenes 4 through an ordinary N–H insertion process [6][7][8][9][10][11][12][13] (Scheme 5). To the best of our knowledge, the discovered processes are the first examples of intramolecular reactions of thiocarbonyl ylides with cyano groups, acting as an electrophile, with subsequent 1,3

Diradical reaction mechanisms in [3 + 2]-cycloadditions of hetaryl thioketones with alkyl- or trimethylsilyl-substituted diazomethanes

• Grzegorz Mlostoń,
• Paulina Pipiak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 716–724, doi:10.3762/bjoc.12.71

• . Remarkably, in no single case, the ‘head-to-head dimerization’ of aryl/hetaryl and dihetaryl substituted thiocarbonyl ylides was observed. Keywords: [3 + 2]-cycloadditions; diazoalkanes; diradicals; 1,3-dithiolanes; reaction mechanisms; thioketones; Introduction Cycloaddition reactions belong to the most

• , leading to unusual dimers 5 of intermediate thiocarbonyl ylides of type 3c [22] (Scheme 2). In a competitive reaction, the latter react with the starting thioketone 1c to give 1,3-dithiolanes of type 6 which are, apparently, also formed via a diradical pathway, leading to the sterically crowded 4,4,5,5

• -thiadiazolines of type 2 can be obtained at low temperature and subsequently used as precursors of new thiocarbonyl ylides. The latter may be potentially useful for the [3 + 2]-cycloaddition reactions with diverse dipolarophiles leading to five-membered S-heterocycles, such as di- and tetrahydrothiophenes, 1,3

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

• Andrey S. Mereshchenko,
• Alexey V. Ivanov,
• Viktor I. Baranovskii,
• Grzegorz Mloston,
• Ludmila L. Rodina and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2015, 11, 504–513, doi:10.3762/bjoc.11.57

• , Poland 10.3762/bjoc.11.57 Abstract The 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3-dicarbonyl compounds (DDC) and thioketones preferably occurs with Z,E-conformers and leads to the formation of transient thiocarbonyl ylides in two stages. The thermodynamically favorable further transformation of C

• stage of the cycloaddition process. Keywords: diazocarbonyl compounds; 1,3-dipolar cycloaddition; 1,3-oxathioles; thiiranes; thiocarbonyl ylides; thioketones; Introduction Dipolar cycloadditions of diazo compounds have been of great interest for a long time as they provide a means for the preparation

• intermediate thiocarbonyl ylides of type 7 from 1a–d and 2a is thermodynamically favorable. The activation energy of the 1,3-dipolar cycloaddition of diazo compounds 1 to thiobenzophenone (2a, ΔG1#) is significantly larger than the decomposition energy of 1,3,4-thiadiazolines 6 (ΔG2#). In line with these data

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• -oxathiole to alkene were performed at the DFT PBE1PBE/6-31G(d) level. Keywords: 1,3-dipolar electrocyclization; 1,5-dipolar electrocyclization; 1,3-oxathioles; thiocarbonyl ylides; thiiranes; thioketones; Introduction Aryl- and alkylsubstituted thioketones exhibit high 1,3-dipolar reactivity towards

• temperature the formation of 1,3-oxathioles 3,7 occurred not via the initial decomposition of diazo compounds 2 and subsequent generation of thiocarbonyl ylides 6. Instead, the way via the initial [2 + 3]-cycloaddition of the diazo compounds with the C=S bond (Scheme 2) seems to be the most likely process

Synthesis of 3-(phenylazo)-1,2,4-triazoles by a nucleophilic reaction of primary amines with 5-chloro- 2,3-diphenyltetrazolium salt via mesoionic 2,3-diphenyltetrazolium- 5-aminides

• Shuki Araki,
• Satoshi Hirose,
• Yoshikazu Konishi,
• Masatoshi Nogura and
• Tsunehisa Hirashita

Beilstein J. Org. Chem. 2009, 5, No. 8, doi:10.3762/bjoc.5.8

• act as a hydride acceptor and 4 itself is transformed to 3-aminoformazan 5. Thus, the formation of triazole 3 is considered to be a dual-path process: via oxidation of the intermediate C and formazan 5. It is worthy to note here that a similar 1,5-dipolar ring closure of type B mesoionic thiocarbonyl

• ylides is known to furnish thiadiazolines [8]. Conclusion It has now been revealed that the 5-chlorotetrazolium salt 2 reacts with primary and secondary amines to give the corresponding 5-aminotetrazolium salts 4. When triethylamine is employed as a base in the reaction with primary amines, deprotonation