Properties of Olean-12-ene-3α,16β,22α,28-tetrol and Some Derivatives

Abstract

Reaction of olean-12-ene-3β,16β,22α,28-tetrol ( chichipegenin ) (1) with methyl orthoformate gives the 16β,22α,28-orthoformate (2). Acetylation of the ortho ester followed by hydrolysis gives the tetrol 3β-monoacetate (5). It is shown that intramolecular hydrogen bonding occurs in the tetrol (1) and the 3β-monoacetate (5) in non-polar solvents. X-Ray crystallographic data on the tetrol and its tetraacetate (4) are reported. The tetrol,C₃₀H₅₀O₄, M 474.72, crystallized in the orthorhombic space group P 2₁2₁2₁ with a 12.363(6), b 31.888(3), c 6.962(3) Ǻ, V 2745(1) Ǻ³, D_c(Z = 4) 1.149 g cm^-3, N = N(unique) 2394, N_o 1878 [I > 1.5σ(I)], N_var 500; R 0.038, R_w 0.040. The tetraacetate , C₃₈H₅₈O₈, M 642.87, crystallized in the monoclinic space group P 2₁, with a 10.603(2), b 16.569(1), c 10.814(1) Ǻ, β 98.72(1)°, V 1877.9(4) Ǻ³, D_c(Z = 2) 1.137g cm^-3 N 3090, R_merge 4.67% for N(unique) 2917, N_o 2663 [I > 2.5σ(I)], N_var 414; R 0.053, R_w 0.050.