Synlett 2019; 30(17): 1995-1999
DOI: 10.1055/s-0037-1611974
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© Georg Thieme Verlag Stuttgart · New York

Thiolate-Initiated Synthesis of Dibenzothiophenes from 2,2′-Bis(methylthio)-1,1′-Biaryl Derivatives through Cleavage of Two Carbon–Sulfur Bonds

Yoshihiro Masuya
,
Yuki Kawashima
,
Takuya Kodama
,
Naoto Chatani*
,
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan   Email: chatani@chem.eng.osaka-u.ac.jp   Email: tobisu@chem.eng.osaka-u.ac.jp
› Author Affiliations
This work was supported by Grant-in-Aid for Scientific Research (18H01978) and Scientific Research on Innovative Area "Precisely Designed Catalysts with Customized Scaffolding" (18H04259) from MEXT, Japan.
Further Information

Publication History

Received: 12 November 2018

Accepted after revision: 11 December 2018

Publication Date:
14 January 2019 (online)


Abstract

A catalytic reaction involving the cleavage of two carbon–sulfur bonds in 2,2′-bis(methylthio)-1,1′-biaryl derivatives is reported. This reaction does not require a transition-metal catalyst and is promoted by a thiolate anion. Notably, based on DFT calculations, the product-forming cyclization step is shown to proceed through a concerted nucleophilic aromatic substitution (CSNAr) mechanism.

Supporting Information

 
  • References and Notes

  • 7 Treatment of 1a-Me (0.20 mmol) with [(allyl)PdCl]2 (5.0 mol%) and NaO t Bu (200 mol%) in DMF (1 mL) under 160 °C for 18 h gave 2a in 97% NMR yield.
  • 8 Treatment of 1j with a stoichiometric amount of NaSMe was reported to give a demethylated compound, along with a small amount of 2j (11%). However, this was not investigated in detail. See: Furia FD, Licini G, Modena G, Valle G. Bull. Soc. Chim. Fr. 1990; 134
  • 9 Dibenzothiophene (2a) [CAS: 132-65-0]; Typical Procedure An oven-dried 5 mL screw-capped vial was charged with 1a-Me (49.2 mg, 0.20 mmol), NaSMe (2.8 mg, 0.04 mmol), and DMF (1 mL) under a gentle stream of nitrogen. The vessel was then sealed and heated at 160 °C for 4 h. The mixture was cooled to r.t. and filtered through a short pad of silica gel, eluting with EtOAc. The eluent was evaporated to give a residue, which was purified by flash chromatography (Rf 0.43, hexane) to give 2a as a white solid (49 mg, 87%). 1H NMR (CDCl3, 399.78 MHz): δ = 7.44-7.47 (m, 4 H), 7.84–7.87 (m, 2 H), 8.15–8.17 (m, 2 H). 13C NMR (CDCl3, 100.53 MHz): δ = 121.7, 122.9, 124.5, 126.8, 135.7, 139.6. HRMS (EI): m/z calcd for C12H8S: 184.0347; found: 184.0349.
  • 10 Calculations were performed with the Gaussian 09, Rev. D01 program (see the Supporting Information): Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR, Scalmani G, Barone V, Mennucci B, Petersson GA, Nakatsuji H, Caricato M, Li X, Hratchian HP, Izmaylov AF, Bloino J, Zheng G, Sonnenberg JL, Hada M, Ehara M, Toyota K, Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao O, Nakai H, Vreven T, Montgomery JA. Jr, Peralta JE, Ogliaro F, Bearpark M, Heyd JJ, Brothers E, Kudin KN, Staroverov VN, Kobayashi R, Normand J, Raghavachari K, Rendell A, Burant JC, Iyengar SS, Tomasi J, Cossi M, Rega N, Millam JM, Klene M, Knox JE, Cross JB, Bakken V, Adamo C, Jaramillo J, Gomperts R, Stratmann RE, Yazyev O, Austin AJ, Cammi R, Pomelli C, Ochterski JW, Martin RL, Morokuma K, Zakrzewski VG, Voth GA, Salvador P, Dannenberg JJ, Dapprich S, Daniels AD, Farkas Ö, Foresman JB, Ortiz JV, Cioslowski J, Fox DJ. Gaussian 09, Revision D.01 . Gaussian, Inc; Wallingford CT: 2013
  • 12 A pathway initiated by a single electron transfer from NaSMe to 1a is unlikely, because this process was found to be endothermic by 66.3 kcal/mol. See Supporting Information for details.
    • 16a See the Supporting Information for further information regarding the reaction pathway of the C-O/C-O bond meta­thesis.
    • 16b C-O/C-S metathesis was also investigated by DFT calculations, which indicated that the nature of the leaving group determines the mechanism, rather than the nature of the nucleo­phile. A better SMe leaving group favors CSNAr, whereas an OMe leaving group favors SNAr.
  • 17 Yanagi T, Otsuka S, Kasuga Y, Fujimoto K, Murakami K, Nogi K, Yorimitsu H, Osuka S. J. Am. Chem. Soc. 2016; 138: 14582