Abstract
A series of 1‐oxo‐1,2,3,4,9,10‐hexahydroxanthene derivatives were synthesized from substituted salicylaldehydes and substituted 1,3‐hexanedione in water at 90°C catalyzed by TEBA. The structure of the product was confirmed by X‐ray analysis. Compared with other synthetic methods, this new method has the advantages of easier workup, milder reaction conditions, high yields (85 ∼ 95%) and environmentally benign procedure.
Acknowledgment
We are grateful to the Foundation of the “Surpassing Project” of Jiangsu Province and Natural Science Foundation of the Education Committee of Jiangsu Province (04KJB150139) for financial support.
Notes
1X‐ray crystallography for 3o: Empirical formula C24H28O4, F W = 380.46, T = 193(2) K, Orthorhombic, space group Pbca, a = 15.559(3) Å, b = 11.1768(19) Å, c = 23.057(4) Å, α = β = γ = 90°, V = 4009.7(11) Å3, Z = 8, Dc = 1.260 Mg/m3, λ(MoKα) = 0.71070 Å, μ = 0.084 mm−1, F(000) = 1632. 3.16°<θ<27.48°, R = 0.0840, wR = 0.1611. S = 1.258, Largest diff. Peak and hole: 0.503 and −0.213 e · Å−3