Synlett 2024; 35(04): 441-444
DOI: 10.1055/a-2113-0212
cluster
11th Singapore International Chemistry Conference (SICC-11)

Photochemical Reaction of 1,2-Naphthoquinone toward Enantioselective Synthesis of γ-Rubromycin: Viability Dependence on Chromophore

Yoshio Ando
,
Daichi Ogawa
,
Fumihiro Wakita
,
,
Ken Ohmori
This research was supported by JSPS KAKENHI (JP19K05452, JP21H04703), The Naito Foundation, and The Shorai Foundation.


Abstract

Aiming at the enantioselective total synthesis of γ-rubromycin, we reported the photochemical reaction of 1,2-naphthoquinone as a promising solution to otherwise-difficult enantiocontrol of the single spiroacetal stereogenic center. The present study examined the applicability of this approach to more functionalized substrates, which revealed viability dependence on the chromophore structure differing in the position and number of methoxy substituents.

Supporting Information



Publication History

Received: 29 May 2023

Accepted after revision: 19 June 2023

Accepted Manuscript online:
19 June 2023

Article published online:
14 August 2023

© 2023. Thieme. All rights reserved

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  • References and Notes

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    • 3b Bringmann G, Kraus J, Schmitt U, Puder C, Zeeck A. Eur. J. Org. Chem. 2000; 2729
  • 6 Atkinson DJ, Brimble MA. Nat. Prod. Rep. 2015; 32: 811
  • 8 For preparation of 1,2-naphthoquinones 4be, see the Supporting Information.
  • 9 For the syntheses of Lawson derivatives 6ae, see the Supporting Information.
    • 10a Kwak JH, Won SW, Kim TJ, Roh E, Kang HY, Lee HW, Jung JK, Hwang BY, Kim Y, Cho J, Lee H. Arch. Pharm. Res. 2008; 31: 133
    • 10b Shukla MR, Sarde AG, Loriya RM, Pachpute VD, Walke NB, Khan TH, Kulkarni SA, Palle VP, Kamboj RK. WO 124828 A1, 2013
  • 12 The experimental procedures and characterization data of spiroacetal 12c are shown as follows: A solution of 1,2-naphthoquinone 4c (12.8 mg, 0.0351 mmol) in CH3CN (3.5 mL) was placed in a Pyrex® two-necked round-bottom flask, and degassed three times by purging with argon under sonication. An LED lamp (Techno Sigma PER-AMP, PAR-448, 680 mW) was inserted into the solution, and the flask was covered with aluminum foil. The solution was irradiated at room temperature for 40 min. Then, to the solution was added cerium(IV) ammonium nitrate (43.0 mg, 0.0784 mmol) in H2O (1.8 mL) at 0 °C. After stirring for 10 min at the same temperature, the reaction was quenched by adding saturated aqueous NaHCO3 at 0 °C. The mixture was extracted with CH2Cl2 (×3), and the combined organic extracts were washed with brine, dried (Na2SO4), and concentrated in vacuo. The residue was purified by PTLC (silica gel, CH2Cl2) to afford spiroacetal 12c (8.3 mg, 68%) as a yellow solid. 12c: Rf 0.54 (hexane/EtOAc = 1:1). 1H NMR (600 MHz, CDCl3): δ = 2.23 (td, J = 13.4, 6.0 Hz, 1 H), 2.39 (ddd, J = 13.4, 5.8, 2.0 Hz, 1 H), 2.82 (ddd, J = 16.5, 6.0, 2.0 Hz, 1 H), 3.25 (d, J = 17.9 Hz, 1 H), 3.30 (ddd, J = 16.5, 13.4, 5.8 Hz, 1 H), 3.46 (d, J = 17.9 Hz, 1 H), 3.95 (s, 3 H), 6.82 (d, J = 8.0 Hz, 1 H), 6.95 (t, J = 8.0 Hz, 1 H), 7.11 (dd, J = 8.6, 2.7 Hz, 1 H), 7.12 (d, J = 8.0 Hz, 1 H), 7.13 (t, J = 8.0 Hz, 1 H), 7.55 (d, J = 2.7 Hz, 1 H), 8.02 (d, J = 8.6 Hz, 1 H). 13C NMR (150 MHz, CDCl3): δ = 21.2, 30.4, 39.5, 56.0, 110.6, 112.2, 116.9, 118.6, 121.0, 122.0, 122.6, 124.9, 127.7, 129.0, 129.2, 135.3, 151.4, 158.5, 164.5, 176.5, 181.9. IR (neat): 2940, 2843, 1674, 1651, 1627, 1592, 1489, 1456, 1362, 1288, 1247, 1226, 1180, 1143, 1095, 1081, 1030, 965, 939, 926, 906, 731 cm–1. HRMS (ESI-TOF): m/z [M + H]+ calcd for C21H17O5: 349.1071; found: 349.1071.