Oxidative Amidation in the Naphthalene Series

Abstract

The successful oxidative spirocyclization of 1- or 2-naphtholic sulfonamides extends oxidative amidation methods to the naphthalene series. A method to prepare N-unsubstituted spirolactam derivatives of 1-naphthol is also presented.

Key words

heterocycles - iodine - phenols - spiro compounds - sulfonamides

• References and Notes

• 1 Wilson MC, Nam S.-J, Gulder TA. M, Kauffman CA, Jensen PR, Fenical W, Moore BS. J. Am. Chem. Soc. 2011; 133: 1971

For reviews, see:
• 2a Ciufolini MA. Canesi S, Ousmer M, Braun NA. Tetrahedron 2006; 62: 5318
• 2b Ciufolini MA, Braun NA, Canesi S, Ousmer M, Chang J, Chai D. Synthesis 2007; 3759
• 2c Liang H, Ciufolini MA. Tetrahedron 2010; 66: 5884
• 3a Tamura Y, Yakura T, Haruta J, Kita Y. J. Org. Chem. 1987; 52: 3927
• 3b Kita Y, Tohma H, Kikuchi K, Inagaki M, Yakura T. J. Org. Chem. 1991; 56: 435

For leading reviews on the chemistry of hypervalent iodine reagents, see:
• 4a Zhdankin VV. Hypervalent Iodine Chemistry: Preparation, Structure and Synthetic Applications of Polyvalent Iodine Compounds. Wiley; Chichester: 2014
• 4b Silva LF. Jr, Olofsson B. Nat. Prod. Rep. 2011; 28: 1722
• 5 Activation of the phenol is likely to form an electrophile that is subsequently intercepted by the O-atom of the amide. The resultant spiro-iminolactone is then hydrolyzed to the final lactone upon aqueous workup.
• 6 Braun NA, Bray J, Ousmer M, Peters K, Peters E.-M, Bouchu D, Ciufolini MA. J. Org. Chem. 2000; 65: 4397
• 7 Liang H, Ciufolini MA. Chem. Eur. J. 2010; 16: 13262
• 8 As found, for example, in a Fukuyama sulfonamide, see: Kan T, Fukuyama T. Chem. Commun. 2004; 353

However, oxidative cyclization of naphtholic carboxylic acids and alcohols to spirocyclic lactones and ethers, respectively, is documented. For examples involving oxidation with hypervalent iodine reagents, see:
• 9a Dean FM, Herbin GA, Matkin DA, Price AW, Robinson ML. J. Chem. Soc., Perkin Trans. 1 1980; 1986
• 9b Dohi T, Maruyama A, Takenage N, Senami K, Minamitsuji Y, Fujioka H, Caemmerer S, Kita Y. Angew. Chem. Int. Ed. 2008; 47: 3787
• 9c Uyanik M, Yasui T, Ishihara K. Angew. Chem. Int. Ed. 2010; 49: 2175
• 9d Dohi T, Takenaga N, Nakae T, Toyoda Y, Yamasaki M, Shiro M, Fujioka H, Maruyama A, Kita Y. J. Am. Chem. Soc. 2013; 135: 4558

For examples involving oxidation with other reagents, see:
• 9e DDQ: De Koning CB, Giles RG. F, Engelhardt LM, White AH. J. Chem. Soc., Perkin Trans. 1 1988; 3209
• 9f KOBr: Katsuri TR, Sattigeri JA, Pragnacharyulu PV. P, Cameroon TS, Pradeep B. Tetrahedron 1995; 51: 3051
• 9g Br₃ ^–: Georghiou PE, Ashram M, Clase HJ, Bridson JN. J. Org. Chem. 1998; 63: 1819
• 9h Pb(OAc)₄: Cox C, Danishefsky SJ. Org. Lett. 2000; 2: 3493
• 10 The choice of sulfonamide substrates was motivated by the fact that they tend to undergo oxidative spirocyclization in excellent yield (ref. 7).
• 11 These materials were prepared from the corresponding naphthols by O-allylation, Claisen rearrangement, and further elaboration of the resultant ortho-allylnaphthols in a conventional fashion, as detailed in the Supporting Information.
• 12a Kenner GW, McDermott JR, Sheppard RC. Chem. Commun. 1971; 636
• 12b For a review, see: Heidler P, Link A. Bioorg. Med. Chem. 2005; 13: 585

Fluoroalcohols such as HFIP are valuable solvents in a number of reactions involving hypervalent iodine species, see:
• 13a Dohi T, Yamaoka N, Kita Y. Tetrahedron 2010; 66: 5775
• 13b Ito M, Ogawa C, Yamaoka N, Fujioka H, Dohi T, Kita Y. Molecules 2010; 15: 1918
• 14 1′-Tosyl-1H-spiro[naphthalene-2,2′-pyrrolidin]-1-one (9a); Typical Procedure: The preparation of this compound illustrates the general procedure for the cyclization of substrates 8. A solution of sulfonamide 8a (20 mg, 0.4 mmol, 1.0 equiv) in TFA (0.7 mL) was slowly added at room temperature over a period of 2 min to a solution of DIB (0.44 mmol, 1.1 equiv) in TFA (0.5 mL) so that the final concentration was 0.3 M. Upon completion of the reaction (TLC, 10 min), the mixture was evaporated to dryness. Chromatographic purification of the residue (silica gel; EtOAc–hexanes, 1:3) provided 9a (15 mg, 74%) as a yellow solid; mp 115–117 °C. IR: 1686 cm^–1. ¹H NMR (300 MHz, CDCl₃): δ = 8.03 (d, J = 7.2 Hz, 1 H), 7.72 (d, J = 8.3 Hz, 2 H), 7.58 (td, J = 7.5, 1.4 Hz, 1 H), 7.36 (td, J = 7.6, 1.1 Hz, 1 H), 7.29–7.24 (m, 3 H), 6.59 (d, J = 9.9 Hz, 1 H), 6.27 (d, J = 9.8 Hz, 1 H), 3.64–3.60 (m, 2 H), 2.42 (s, 3 H), 2.26–2.03 (m, 2 H), 2.02–1.95 (m, 2 H). ¹³C NMR (75.5 MHz, CDCl₃): δ = 198.4, 143.2, 137.4, 137.1, 136.6, 134.8, 129.3, 128.7, 128.0, 127.7, 127.6, 127.5, 124.5, 70.9, 48.9, 39.5, 23.0, 21.6. HRMS: m/z [M + Na]⁺ calcd for C₂₀H₁₉NO₃SNa: 376.0983; found: 376.0983. 1′-(Methylsulfonyl)-2H-spiro[naphthalene-1,2′-pyrrolidin]-2-one (11a): The cyclization of 2-naphthol-derived substrates 10 was achieved by the same procedure detailed above. Thus, 10a (25 mg) afforded 11a (16 mg, 67%) after column chromatography (EtOAc–hexane, 2:3) as a white solid; mp 116–118 °C. IR: 1672 cm^–1. ¹H NMR (300 MHz, CDCl₃): δ = 7.62 (d, J = 7.8 Hz, 1 H), 7.47–7.42 (m, 2 H), 7.32–7.31 (m, 2 H), 6.17 (d, J = 9.9 Hz, 1 H), 3.96 (dt, J = 8.7, 6.2 Hz, 1 H), 3.76 (dt, J = 8.7, 7.0 Hz, 1 H), 3.10 (s, 3 H), 2.38 (dt, J = 12.0, 7.1 Hz, 1 H), 2.17 (quintet, J = 6.6 Hz, 2 H), 2.07–1.98 (m, 1 H). ¹³C NMR (75.5 MHz, CDCl₃): δ = 200.5, 146.5, 146.0, 130.6, 129.8, 128.5, 127.7, 125.8, 123.7, 75.8, 49.9, 44.2, 40.0, 22.8. HRMS: m/z [M + Na]⁺ calcd for C₁₄H₁₅NO₃SNa: 300.0670; found: 300.0665. 1′-(Methylsulfonyl)-1H-spiro[naphthalene-2,2′-pyrrolidine]-1,5′-dione (15a): A solution of 14a (19 mg, 0.1 mmol, 1.0 equiv) in HFIP (2.0 mL) was added to a solution containing DIB (0.11 mmol, 1.1 equiv) in TFA (0.23 mL) at room temperature so that the final concentration was 0.05 M. Upon completion of the reaction (TLC, 5–12 min), the reaction mixture was evaporated to dryness. Chromatography of the residue (silica gel; EtOAc–hexane, 3:7) gave 15a (8 mg, 42%) as a white solid; mp 169–171 °C. IR: 1737, 1686 cm^–1. ¹H NMR (300 MHz, CDCl₃): δ = 8.05 (d, J = 7.7 Hz, 1 H), 7.64 (t, J = 7.5 Hz, 1 H), 7.42 (t, J = 7.6 Hz, 1 H), 7.30–7.27 (m, 1 H), 6.61 (d, J = 9.8 Hz, 1 H), 6.43 (d, J = 9.8 Hz, 1 H), 3.38 (s, 3 H), 2.84–2.58 (m, 2 H), 2.33 (ddd, J = 13.4, 9.4, 3.9 Hz, 1 H), 2.20–2.09 (m, 1 H). ¹³C NMR (75.5 MHz, CDCl₃): δ = 197.1, 174.7, 137.5, 135.8, 135.3, 128.6, 128.1, 127.9, 127.4, 124.7, 71.4, 41.6, 29.8, 28.9. HRMS: m/z [M + Na]⁺ calcd for C₁₄H₁₃NO₄SNa: 314.0463; found: 314.0468. 1H-spiro[naphthalene-2,2′-pyrrolidine]-1,5′-dione (16): A solution of sulfonamide 15c (20 mg, 0.05 mmol, 1.0 equiv) in MeCN (1.0 mL) was added at room temperature to a solution of PhSH (16 mg, 15 μL, 150 μmol, 3.0 equiv) in MeCN (0.4 mL) containing suspended K₂CO₃ (28 mg, 0.2 mmol, 4.0 equiv). DMSO (0.1 mL) was then added to the reaction mixture and stirring was continued at room temperature for 2 h, after which time TLC showed that the reaction was complete. The reaction was quenched with H₂O (5 mL) and extracted with EtOAc (3 × 5 mL). The combined extracts were washed with brine (5 mL), dried (Na₂SO₄), and evaporated. The residue was dried under high vacuum and purified by flash column chromatography (silica gel; EtOAc–hexane, 3:4) to provide 16 (8 mg, 78%) as a white solid; mp 131–133 °C. IR: 3430–3100 (br), 1698 cm^–1. ¹H NMR (300 MHz, CDCl₃): δ = 8.03 (d, J = 7.6 Hz, 1 H), 7.62 (td, J = 7.6, 1.3 Hz, 1 H), 7.41 (td, J = 7.7, 0.7 Hz, 1 H), 7.30–7.29 (m, 1 H), 6.62 (d, J = 9.8 Hz, 1 H), 6.18 (d, J = 9.8 Hz, 1 H), 5.57 (br s, 1 H), 2.71–2.59 (m, 1 H), 2.46–2.31 (m, 2 H), 2.17–2.05 (m, 1 H). ¹³C NMR (75.5 MHz, CDCl₃): δ = 199.4, 178.8, 137.1, 135.3 (2C), 128.7, 127.9, 127.7 (2C), 127.0, 65.0, 32.2, 28.2. HRMS: m/z [M + Na]⁺ calcd for C₁₃H₁₁NO₂: 236.0687; found: 236.0687.