Oxadisilole-Fused Isoindole

Abstract

The first synthesis of monooxadisilole- and bisoxadisilole-fused isoindoles and their [4+2]-cycloaddition reactions are reported. Deprotection of the cycloadducts leads to the formation of oxadisilole-fused benzoquinones. The structure of the bisoxadisilole-fused isoindole (2b) is confirmed by X-ray analysis.

Key words

isoindole - cycloaddition reactions - oxadisilole-fused benzoquinone

References and Notes

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• 10a

  Crystallographic data for 2b have been deposited with the Cambridge Crystallographic Data Centre (CCDC 611996).

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9

Compound 1b: mp 190-192 °C; ¹H NMR (400 MHz, CDCl₃): δ = 0.37 (s, 12 H), 1.67 (s, 9 H), 7.65 (s, 2 H), 7.68 (s, 2 H); ¹³C NMR (101 MHz, CDCl₃): δ = 1.3, 27.9, 85.0, 110.3, 124.6, 125.7, 139.3, 149.5; IR (KBr): 2979, 1752, 1354, 1246, 1145, 931 cm^-1; HRMS: m/z [M + H]⁺ calcd for C₁₇H₂₆NO₃Si₂: 348.1446; found: 348.1451. Compound 2b: mp 208-210 °C; ¹H NMR (400 MHz, CDCl₃): δ = 0.42 (s, 12 H), 0.46 (s, 12 H), 1.69 (s, 9 H), 7.60 (s, 2 H); ¹³C NMR (101 MHz, CDCl₃): δ = 1.0, 2.4, 27.9, 85.4, 111.2, 125.0, 144.6, 146.6, 149.5; IR (KBr): 2957, 1749, 1412, 1253, 1154, 941 cm^-1; HRMS: m/z [M]⁺ calcd for C₂₁H₃₅NO₄Si₄: 477.1638; found: 477.1646.

13

Compound 26: mp 216-218 °C; ¹H NMR (400 MHz, CDCl₃): δ = 0.44 (s, 12 H), 7.81-7.83 (m, 2 H), 8.33-8.35 (m, 2 H), 8.49 (s, 2 H); ¹³C NMR (101 MHz, CDCl₃): δ = 0.7, 127.2, 129.2, 132.9, 133.5, 134.2, 155.9, 183.9; IR (KBr): 2951, 1676, 1302, 1246, 935 cm^-1; HRMS: m/z [M + H]⁺ calcd for C₁₈H₁₉O₃Si₂: 339.0867; found: 339.0878. Compound 27: mp 356-358 °C; ¹H NMR (400 MHz, CDCl₃): δ = 0.45 (s, 24 H), 8.50 (s, 4 H); ¹³C NMR (101 MHz, CDCl₃): δ = 0.8, 129.2, 132.9, 156.0, 184.7; IR (KBr): 2959, 2924, 1668, 1300, 1251, 1108, 937 cm^-1; HRMS: m/z [M + Na]⁺ calcd for C₂₂H₂₈O₄Si₄Na: 491.0962; found: 491.0961. Compound 29: mp 310-312 °C; ¹H NMR (400 MHz, CDCl₃): δ = 0.45 (s, 12 H), 0.51 (s, 12 H), 7.83-7.86 (m, 2 H), 8.33-8.35 (m, 2 H); ¹³C NMR (101 MHz, CDCl₃): δ = 0.1, 2.1, 127.4, 132.9, 134.5, 135.6, 151.6, 161.5, 185.3; IR (KBr): 2955, 2924, 1668, 1287, 1250, 948 cm^-1; HRMS: m/z [M + H]⁺ calcd for C₂₂H₂₉O₄Si₄: 469.1137; found: 469.1148.