Structures of the Diterpene-Carboxylic Acids from Solidago altissima L.

Abstract

Acidic components of S. altissima roots were methylated with diazomethane and repeatedly chromatographed on silica gel to give two oily bitter principles [3] (C₂₆H₄₀0₄, bp 180-190° C/ 0.01 mmHg) and [4] (C₂₆H₄₀0₄, bp 190-195° C/0.02 mmHg), and one crystalline bitter principle, methyl altissimate, [16] (C₂₁H₃₂0₃, bp 108-109° C). Upon reduction with LiAlH₄, [3] gave the diol [5] and seqcis-2-methyl-2-butenol-1 [8], and [4] gave the same diol [5] and seqtrans-2-methyl-2-butenol-1 [7]. The acetylation of [5] gave the monoacetate [9], which was oxidized with Jones' reagent, and reduced by the Huang-Minlon method to give kolavenol [12]. The monoketone [14] derived from [5] possessed two active hydrogens in the α position of the carbonyl group. Methyl altissimate [16] was identical with the neutral product obtained from chromic acid oxidation of methyl kolavenate Based on the above chemical evidences and the spectral properties of derivatives, it was determined that [3], [4] and [16] were methyl 6-angeloyloxykolavenate, 6-tygroyloxykolavenate and 2-ketokolavenate, respectively.