LXII.—A lævorotatory modification of quercitol

Abstract

By FREDERICK BELDING POWER and FRANK TUTIN. QUERCITOL has hitherto only been found in the fruits (acorns) of certain species of Quevcus, in which it exists as a dextrorotatory modification. The laevorotatory modification now described was obtained by us from the leaves of Gymn.ema sylvesti-e (Br.), a plant belonging to the family of Asclqhatlacece, and indigenous to Banda and the Deccan-Peninsula (compare Pharmacographia Indica," vol. 11, p. 450). In the course of a n examination of a large quantity of Gymnema leaves, a colourless, crystalline substance having the empirical formula CGH,,06 was isolated, which melted a t 1 7 4 O and had [a].-73.9'. When heated at l l O o , it lost one molecular proportion of water; i t formed a penta-acetyl derivative, C,Hp(OoC,H,0)5, and a pentabenzogl derivative, C,€l,(O*C,H,O),. From these facts i t was seen that the above formula, C6Hl4O6, could be appropriately modified to C6H1(OH),,H,0, which represents the substance as a hydrated isomeride of quercitol. The constitutional formula of quercitol, first proposed by Kanonnikoff, represents it as pentahydroxyhexahydrobenzene, Y? HO*HC C€€*OH HO~HC CEPOH \/ C'H*OH The correctness of this formula was proved by Kiliani and Schaefer (Ber., 1896, 29, 1762), who obtained malonic acid on oxidation with potassium permanganate. Moreover, the same investigators have shown that d-quercitol, on oxidation with aqueous bromine, forms a diketone, CGHSO,, which was isolated in the form of its dihydrazone, The substance isolated from the leaves of Gprnnerncc sylvestre, when oxidised with potassium permanganate and sodium hypobromite respectively, showed a behaviour identical with that of d-quercitol. Like the latter, i t afforded, on the one hand, malonic acid, and, on the other, a diketotrihydroxyhexahydrobenzene, which was isolated in the form of its dihydrazone (m. p. 209'). It was thus demonstrated that our substance has the same constitution as d-quercitol, and can only ditfer from the latter stereo C1SH2003N4'

The Stereoisomerism of Cyclohexane Derivatives.

“…Another pentol found in Gymnema sylvestre Br. has been designated "Z-quercitol" (245), although it is not an antipode of dextroquercitol. A levorotatory compound of the same composition, recovered from Viburnum tinus L., has been named viburnitol (126).…”

A New Source of 'l-Quercitol ' (Viburnitol)

“…and its two derivatives found in the present work are compared in Table 1 with those reported by Power and Tutin (4). The agreement between some of the figures is excellent but the wide discrepancies in others a t first rendered the identification doubtful.…”

Organic chemistry section:

“…Similarly, phenylosazones have been obtained by oxidation of (+)-protoquercitol [15] with aqueous bromine, and from oxidation of (-)-viburnitol with sodium hypobromite [16]; however, for the last two reactions, the yields were not stated.…”