No abstract

An amorphous, optically active, heat and light sensitive, polyoxyphenolic acid (pR, = 3) has been isolated from the mixture of polyoxyphenols present in the aqueous extractive of western red cedar. Analyses of crystalline derivatives are consistent with a molecular formula of C2~H22010 Color tests, spectra, methylation, and allcaline nitrobenzene oxidation results indicate it t o be a propylphenol dimer, a lignan acid, in which one aromatic ring is 3-methoxy-4-hydroxyphenyl and the other is 3,4-dihydroxy-5-methoxyphenyl. Acetylation results and lactone formation require the presence of three alcoholic hydroxyls, one of which is in the 7 position to the carboxyl.I n a previous paper ( I ) , the presence in the acetone extractive of western red cedar of several water-soluble polyoxyphenols was reported. This phenolic mixture constituted 4 to 5% of wood samples having acetone solubilities of 10 to 14%. These substances were also extracted with water and accounted for the main portion (85-95%) of the hot-water extractive of butt outer heartwood which was found to have hot-water solubilities ranging from 10 to 23y0 (2). This indicated high content of natural phenolic substances together with the availability of large volumes of western red cedar wood a s mill and forest residue in British Columbia prompted a detailed investigation of the chemistry of t h e phenolic constituents.Paper chromatography of the aqueous extractive, a brown resin, showecl the presence of a t least seven different phenols and arabinose. By stea~iling the nlixture during aqueous extraction of the \\rood, the steam-volatile tropolones, thujic acid ancl nlethyl thujate, were virtually eliminated. T h e arabinose and other non-pheilols in the extractive were removed by treatment with lead acetate solution and regeneration of the phenols fro111 the precipitated lead salts. Attempts to fractionate the regenerated phenols with a variety of solvents were made, and the separation efficiency was checked by means of paper chromatography of the fractions. 111 this manner it was established that a major cornponent (R, = 0.9, carbon dioxide -water) was very soluble in water and, compared with the others, practically insoluble in eth1.l acetate. Thus, thorough extraction of the phenolic mixture with ethyl acetate gave a residue which was paper chromatograpl~ically pure in respect to carboh~clrates and other phenols. This product \vas an a~norphous brown powder which gave positive tests for p\,rocatechol, methoxyl, and carboxyl groups. In view of its acidity and source, this substance was ternled plicatic acid.Additional quantities of plicatic acid were isolated simply by extracting it from the mixture of phenols in methyl ethyl ketone with sodium bicarbonate s o l u t i o~~. T h e yield was 40y0 of the aqueous extractive, but since the product was brown in color and failed t o crystallize or give crystalline methyl ethers with diazomethane, ~ililder methods of isolation not involving the use of acids and alltalis n-ere investigated.Colunln chromatog...

This manuscript describes an unprecedented and efficient synthesis of a new DPP scaffold, 2,5-dibutyl-3,6-dimethyl-1H,2H,4H,5H-pyrrolo­[3,4-c]­pyrrole-1,4-dione (DMDPP), containing methyl groups at the 3,6-positions as a precursor to preparing 3,6-divinyl-substituted DPP compounds. Subsequently, following the synthesis of DMDPP, we performed an efficient and mild C–H functionalization of the methyl groups with a variety of aromatic aldehydes to synthesize the first examples of 3,6-divinyl-substituted DPP compounds in moderate to good yields.

The structure of the tenth in the series of novel lignans from the heartwood of western red cedar (Thujaplicata Donn) has been determined as 2-(3″,4″-dihydroxy-5″-methoxybenzylidene)-3-(4′-hydroxy-3′-methoxybenzyl)-butyrolactone (γ-thujaplicatene) (1) by spectrometric methods and comparison with synthetic derivative reactions. The discovery of this lignan with a double bond conjugated with an aromatic ring confirms previously suggested biosynthetic routes to the cedar lignans.