A mixture of two new cyanogenetic lipids from the seeds of Ungnadia speciosa have been structurally characterized.WE WISH to report the structure determination of a mixture of two new cyanogenetic lipids which are based upon the same aglycone but differ in the degree of saturation of their Czo lipid moieties (I). The mixture was obtained from the seed oil of a small tree, Ungnadiu speciosa, which is indigenous to the southwestern United States and northern Mexico. Although several cyanogenetic lipids are known to occur in nature,ls5 the detailed structure has been reported Is2 for only one other mixture (II).A pentane extract obtained from the seeds of Ungnadia speciosa afforded after chromatography* a mixture of two? cyanogenetic lipids to which we assign formula I based on the evidence presented below. Because the mixture was difficult to separate and appeared to be based on a single aglycone, it was treated as a single entity during the course of this investigation.Although the new cyanogenetic lipid material readily liberated HCN by a standard picrate test,lp2p6 the i.r. spectrum for the material did not display a band for nitrile absorption; however, this latter result is in accord with the available i.r. data for similar substances. The i.r. spectrum did exhibit bands at 1010 and 927 cm-l which are typical for a terminal methylene group in the aglycone moiety of a cyanogenetic lipid.'p2 The NMR spectrum of the material was particularly informative with regard to the structural features of the aglycone moiety: the cyanohydrin proton (H,) appeared as a slightly broadened singlet at 5.79 6, the &-vinyl methyl gave a finely split singlet at 1.89 6 and the two C,-terminal methylene protons gave two finely split singlets at 5.17 and 5.33 8. Spin decoupling experiments established that the small coupling observed for the C&-vinyl methyl group resulted* The cyanogenetic compounds from Ungnadia speciosa, unlike those of Cordia verbenacea,1*2 were readily separated from various glycerides by silica gel chromatography. The glycerides obtained in the present investigation afforded upon trans-esterification and GLC analysis, the following relative amounts of fatty acid methyl esters: Cl6 (6*2x), &-unsaturated (660x), &-saturated (3.6%) and &,-saturated (trace).t Traces of other cyanogenetic lipids were probably present based upon the occurrence of minor peaks in the GLC of the methyl esters of the fatty acids obtained from the cyanogenetic lipid material.5 M. G. KASBEKER and N. V. BRINGI, J. Am. Oil Chemists' Sot. 46,183 (1969).6 T. WOOD, J. Sci. FoodAgri. 16,300 (1965).r K. L. MIKOLAJCZAK, D. S. SEIGLER, C. R. SMEH, JR., I. A. WOLFF and R. B. BATES, Lipids 4,617 (1969). z D. S. SEIGLER, K. L. MIKOLAJCZAK, C. R. SMITH, JR., I. A. WOLFF and R. B. BATES, Chem. Phy. Lipid 4, 147 (1970). 3 L. ROSENTHALER, Schweiz. Aporh. 58, 17 (1920); Chem. Abs. 14,556 (1920). + M. K. KUNDU and C. BANDYOPADHYAY, J. Am. Oil Chem. Sot. 46,23 (1969). from interaction with the terminal methylene protons and the cyanohydrin proton. Coupling was also detected between the latter proton and the methylene group.When the mixture was hydrogenated,* material was obtained which appeared to be a single substance and whose NMR spectrum exhibited a doublet (J = 5.6 c/s) at 5.18 6 for the cyanohydrin proton and two overlapping doublets (J = 6.0 c/s) at 1.22 8 for the C4 and C, methyl groups. The i.r. spectrum for the hydrogenated material did not exhibit bands for a terminal methylene group. These spectral findings for the material before and after hydrogenation indicated that the structure of the aglycone moiety of the mixture of new cyanogenetic lipids must be 1-cyano-2-methylprop-2-ene-l-01 as shown in I.7The only remaining question concerned the nature of the two lipid groups. The NMR spectrum of the original cyanogenetic lipid material exhibited a number of signals characteristic for long-chain lipid groups: the u-protons of the fatty acids gave rise to a triplet (J 7.2 c/s) at 2.39 6 (unchanged in the hydrogenated material) a distorted triplet appeared at 088 6 for the terminal methyl groups, the vinyl protons appeared as a triplet centered at 5.36 6 (J = 4.6 c/s) and a large broad signal for the methylene protons was centered at 1.25 8. The lipid groups were identified by converting them to their methyl esters by transesterification and comparing the methyl esters by GLC with authentic standards, Thus, the lipid groups were found to consist of 71-6 per cent of a C,, mono-unsaturated fatty acid group and 28.4 per cent of the Czo saturated fatty acid moiety.Finally, the mass spectrum of the original mixture of cyanogenetic lipids showed parent ions at nz/e 389 and 391 whereas the mass spectrum of the hydrogenated material showed only a single parent peak at 393.Based on all the above data, structure I is assigned to the two cyanogenetic lipids from Ungnadia speciosa: they are, therefore, similar to the cyanogenetic lipids (II) from Cordia verbenacea.; Glaucous lines of barley have the fldiketone, hentriacontan-14,16-dione, in their surface lipids. The aliphatic alcohol of barley surface lipid is l-hexacosanol, and the principal hydrocarbons have carbon numbers 25,27,29,31 and 33. There is no apparent biosynthetic relationship between the primary alcohol and the fi-diketone; however, there may be some relationship between the p&ketone and the hydrocarbons.