Yellow birch, Betula alleghaniensis, is a dark-barked birch species that is widely utilized in the northeastern region of the United States for pulp and solid wood products. Currently, the bark is used only as a low value fuel source. In this study, the triterpenoid composition of the outer bark of B. alleghaniensis was investigated in order to evaluate potential for use as a resource for specialty chemicals. Seventeen triterpenoids, including four new compounds, were isolated and identified. Previously known compounds included lupeol, lupenone, betulone, betulin, betulonic acid, lupenyl formate, lup-20(29)-ene-30-01-3-one, lup-20(29)-ene-3P,30-diol, lup-20(29)-ene-28-ol-30-al, 29-norlupan-3P-ol-20-one, lupan-20-01-3-0ne, lupan-3P,20-diol, and lupan-3P-ol-29-oic acid. The four new compounds isolated from yellow birch were lup-20(29~-ene-28-ol-3-one-30-al,29-norlupan-3,20-&one, 29-norlupan-28-01-3,20-dione, and lupan-20,28-diol-3-one.the United States. The wood is commonly used for furniture, flooring, and cabinetry. It has been estimated that about threefourths of the lumber marketed as "birch', approximately 145,000,000 board feet per year, is yellow birchl. It is also a preferred pulp species because of its long fiber length. Such widespread utilization of this species generates a vast quantity of waste bark which currently is used only as a fuel for energy production. The utilization of this bark for higher value products is thus a subject of considerable interest. In order to adequately evaluate potential uses of the bark, it is necessary to investigate the composition of the bark.barked birch species are rich in pentacyclic triterpenoid compounds, particularly betulin. In studies of the European birch species, B. uerrucosa and B. pubescens, it was found that the barks contained up to 40%, by weight, total triterpenoids with betulin alone comprising up to 35% of the weight of the outer bark2. Such unusually high levels of a single component make the bark an especially attractive resource for further utilization.While the barks of European and Japanese birch species have been thoroughly investigatedz-9, little is known regarding the composition of the barks of species native to the United States. In a previous study in our laboratory, we determined that betulin was the major triterpenoid component in the outer barks of four native whitebarked species: B. papyriferu (paper birch), B. populifolia Marsh. (gray birch), B. cordifolia Regel. (mountain paper birch), and B. X caerulea Blanch. (blue birch). In these species, betulin comprised 6-22% of the outer bark and contributed about 75% of the triterpenoid content. Lupeol was the second most abundant triterpenoid, accounting for 0.2-2%, by weight, of the barklo.In addition to the white-barked species discussed above, two dark-barked birch species also are native to the northeastern U.S. In an earlier studyll, we analyzed the outer bark of black birch and found that the triterpene composition was significantly different than that observed in the white-barked specie...