Synlett 2020; 31(02): 153-157
DOI: 10.1055/s-0037-1611767
cluster
© Georg Thieme Verlag Stuttgart · New York

Sulfoxide-Directed Iterative Assembly into Oligoarenes

Tomoyuki Yanagi
,
Keisuke Nogi
,
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan   Email: yori@kuchem.kyoto-u.ac.jp
› Author Affiliations
This work was supported by JSPS KAKENHI Grant Numbers JP16H04109, JP18H04254, JP18H04409, and JP18K14212. T.Y. acknowledges a JSPS Predoctoral Fellowship. H.Y. thanks The Mitsubishi Foundation for financial support.
Further Information

Publication History

Received: 01 January 2019

Accepted after revision: 10 February 2019

Publication Date:
28 March 2019 (online)


Published as part of the Cluster Iterative Synthesis

Abstract

A series of oligoarenes have been synthesized via sulfoxide-based iterative dehydrogenative transformations. By utilizing the sulfinyl moieties as on/off-switchable directing groups, overreactions and/or undesired oligomerizations were completely suppressed. Since the dehydrogenative couplings were not hampered by steric hinderance, sterically encumbered oligoarenes were synthesized.

Supporting Information

 
  • References and Notes

  • 3 Ernst JT, Kutzki O, Debnath AK, Jiang SJ, Lu H, Hamilton AD. Angew. Chem. Int. Ed. 2002; 41: 278
  • 7 Watson also accomplished the synthesis of oligoarenes by using BMIDA esters, see: Fyfe JW. B, Seath CP. Watson A. J. B. Angew. Chem. Int. Ed. 2014; 53: 12077
  • 8 Nakao Y, Chen J, Tanaka M, Hiyama T. J. Am. Chem. Soc. 2007; 129: 11694
  • 10 Yanagi T, Otsuka S, Kasuga Y, Fujimoto K, Murakami K, Nogi K, Yorimitsu H, Osuka A. J. Am. Chem. Soc. 2016; 138: 14582
  • 11 For a review, see: Huang X, Klimczyk S, Maulide N. Synthesis 2012; 44: 175
  • 14 Fernández-Salas JA, Pulis AP, Procter DJ. Chem. Commun. 2016; 12364
  • 15 Dehydrogenative coupling of aryl sulfoxides with phenols; Typical procedure (GP1) A modification of the procedure that we reported was used (see ref. 10). The synthesis of 8 is representative. A Schlenk tube was charged with di(2-naphthyl) sulfoxide (7; 604 mg, 2.0 mmol), 2-naphthol (2; 576 mg, 4.0 mmol), and CH2Cl2 (20 mL). To the tube was added trifluoroacetic anhydride (0.42 mL, 3.0 mmol), and the resulting solution was stirred at 25 °C for 1 h, before saturated aqueous NaHCO3 (10 mL) was added. The resulting biphasic solution was extracted with EtOAc (3 × 15 mL). The combined organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane/EtOAc = 7.5:1) to give 8 (625 mg, 1.46 mmol, 73%) as a colorless oil.
  • 16 Methylation of hydroxy groups; Typical procedure (GP2) The methylation of 8 to the corresponding ether 8′ is representative. A Schlenk tube was charged with 8 (540 mg, 1.26 mmol), K2CO3 (340 mg, 2.50 mmol), and acetone (3.0 mL). Iodomethane (117 µL, 1.89 mmol) was added, and the resulting solution was stirred at 60 °C. Progress of the reaction was monitored by TLC. After completion of the reaction, aqueous HCl (2 mL) was added and the resulting mixture was extracted with CH2Cl2 (3 × 5 mL). The combined organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure to afford sulfide 8′ (491 mg, ca. 1.1 mmol) with some impurities. The 8′ was oxidized to the corresponding sulfoxide without further purification in accordance with GP3.
  • 17 Oxidation of aryl sulfide; Typical procedure (GP3) The synthesis of 9 is representative. To a solution of 8′ (491 mg, ca. 1.1 mmol) in CH2Cl2 (5 mL) was added m-chloroperbenzoic acid (containing ca. 30% H2O, 274 mg, 1.1 mmol) portionwise at 0 °C. The resulting solution was allowed to warm to room temperature and stirred at the same temperature. Progress of the oxidation was monitored by TLC. After completion of the reaction, saturated aqueous NaHCO3 (3 mL) was added and the resulting mixture was extracted with EtOAc (3 × 20 mL). The combined organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane/EtOAc, 1:1) to give 9 (401 mg, 0.87 mmol, 69% from 8) as a white solid.
  • 18 The relative stereochemistry of each diastereomer was difficult to assign. Due to difficulty in separating diastereomers by column chromatography on silica gel, we characterized the products as mixtures of diastereomers, except compounds 6 and 10.
  • 19 It is known that racemization of sulfoxide can proceed in the presence of acid anhydrides. Therefore, we did not separate the diastereomers and they were used as a mixture for the second arylation, see: Oae S, Kise M. Tetrahedron Lett. 1967; 1409
  • 21 Annulative construction of benzofurans; Typical procedure (GP4) A modification of the procedure that we reported was used.[3] The synthesis of 15a is representative. A Schlenk tube was charged with 13 (93.1 mg, 0.20 mmol), alkenyl sulfoxide 14a (80.3 mg, 0.24 mmol), and CH2Cl2 (2.0 mL). To the tube was added trifluoroacetic anhydride (34 μL, 0.24 mmol), and the resulting solution was stirred at 25 °C for 1 h, before saturated aqueous NaHCO3 (12 mL) was added. The resulting biphasic solution was extracted with CH2Cl2 (3 × 2 mL). The combined organic layer was dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane/EtOAc, 20:1) to give 15a (62.0 mg, 0.11 mmol, 54%) as a colorless oil.
  • 22 For a review on the synthesis of fully substituted arenes, see: Suzuki S, Yamaguchi J. Chem. Commun. 2017; 1568