Regioselective Synthesis of Novel 7-5-8-Fused Oxabridged Tricyclic Molecules via Consecutive Dipolar Cycloaddition of Pentafulvenes with 3-Oxidopyrylium Betaines

Abstract

Pentafulvenes undergo consecutive dipolar cycloadditions with various substituted oxidopyrylium betaines resulting in the formation of a new class of structurally interesting 7-5-8-fused oxabridged tricyclic molecules.

Key words

Pentafulvenes - oxidopyrylium betaines - consecutive dipolar cycloaddition - 7-5-8-fused tricyclic molecules

References

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11

X-ray crystal data for 4b; CCDC 282936; Empirical formula C₁₈H₁₈O₄; Formula weight 298.32; T = 273 (2) K, λ = 0.71073 Å; Crystal system = triclinic; Space group P-1; Unit cell dimensions a = 6.5522 (11) Å, α = 97.335 (3)°, b = 8.6272 (15) Å, β = 103.040 (3)°, c = 13.763 (2) Å, γ = 102.074 (3)°; V = 728.6 (2) A³; Z = 2; D_calcd = 1.360
Mg/m³; Absorption coefficient 0.096 mm^-1; F(000) = 316; Crystal size 0.24 × 0.16 × 0.10 mm; Theta range for data collection 1.54° to 28.23°; Index ranges -8 £ h £ 7, -10 £ k £ 11, -17 £ 1 £ 16; Reflections collected 4440; Independent reflections 3240 [R(int) = 0.0186]; Refinement method Full-matrix least-squares on F2; Data/restraints/parameters
3240/0/201; Goodness-of-fit on F ² 1.046; Final R indices
[I > 2σ(I)] R1 = 0.0685, wR2 = 0.1777; R indices (all data) R1 = 0.1065, wR2 = 0.2234; Largest diff. peak and hole 0.486 and -0.287 e·A^-3.

12

X-ray crystal data for 5a; CCDC 285388; Empirical formula C₁₉H₂₀O₄; Formula weight 312.35, T = 273 (2) K, λ = 0.71073 Å; Crystal system = orthorhombic; Space group Pbca; Unit cell dimensions a = 13.3749 (14) Å, α = 90°, b = 12.4231 (13) Å, β = 90°, c = 18.502 (2) Å, γ = 90°; V = 3074.2 (6) A³; Z = 8; D_calcd 1.350 Mg/m³; Absorption coefficient 0.094 mm^-1; F(000) = 1328; Crystal size 0.20 × 0.14 × 0.06 mm; Theta range for data collection 2.20° to 25.00°; Index ranges -14 £ h £ 15, -14 £ k £ 14, -22 £ 1 £ 12; Reflections collected 14337; Independent reflections 2701 [R(int) = 0.0533]; Refinement method Full-matrix least-squares on F ²; Data/restraints/parameters 2701/0/211; Goodness-of-fit on F ² 1.187; Final R indices [I > 2σ(I)] R1 = 0.0678, wR2 = 0.1324; R indices (all data) R1 = 0.0861, wR2 = 0.1399; Largest diff. peak and hole -0.243 and -0.187 e·A^-3.