were washed with brine (20 mL) and dried. Removal of solvent in vacuo provided 26 mg of a white solid, which was dissolved in methanol-tetrahydrofuran (5 mL/2 mL) and treated with perchloric acid (2 drops).After 15 min, the solution was diluted with pH 8 phosphate buffer (30 mL) and extracted with ethyl acetate (4 X 50 mL). The combined organic layers were dried, the solvent was removed under reduced pressure, and the residue was chromatographed (TLC grade silica gel, 18% ethyl acetate in petroleum ether) to yield 9 mg (43%) of 3-palmitate ester 38 as a white solid and 4 mg (13%) of 3,5-dipalmitate ester 39.For 38: mp 120-125 'C; IR (thin film, cm-I) 3550-3250 (broad), 1 H), 4.51 (s, 1 H), 4.35 (d, J = 11.5 Hz, 1 H), 3.97 (d, J = 11.5 Hz, 1 H), 3.95-3.85 (m, 2 H), 3.38 (br s, 1 H), 2.44 (br s, 1 H), 2.23 (dd, J = 15.2,11.7Hz,1H),2.16(t,J=7.6Hz,2H),1.75(t,J=8Hz, 1 H), 1.67 (d, J = 1.1 Hz, 3 H), 1.62-1.50 (m, 5 H), 1.50-1.15 (m, 26 H), 0.91 (t, J = 6.6 Hz, 3 H), 0.88-0.82 (m, 1 H); MS, m / z (FAB, M+ + H) calcd 533.3842, obsd 533.3837. Diesterification of 3. By use of the procedure described above, but with 13 mg (0.032 mmol) of 3, 16 mg (0.06 mmol) of palmitoyl chloride, and 28 mg (0.154 mmol) of 4-(dimethy1amino)pyridine in 1 mL of toluene, there was isolated exclusively the dipalmitate 39 ( I l .4 mg, 47%) after chromatography (TLC grade silica gel, 12% ethyl acetate in petroleum ether): mp 80-83 'C; IR (thin film, cm-l) 3530, .81-1.50 (m, 13 H, including CH, singlet at 1.68), 1.40-1.20 (br s, 48 H), 1.15-0.93 (m, 2 H), 0.88 (t, J = 6.5 Hz, 6 H); MS, m / z (FAB, M+ + H) calcd 772, obsd 772.Acknowledgment. This research was made possible by t h e generous financial support of t h e National Institutes of Health (Grant CA-12115). The biological assays were performed a t the Eli Lilly Co.Note Added in Proof. The results of the irritant assays involving 38 and 39 on the mouse e a r have now been completed courtesy of Professor Hecker (Heidelberg). Following a standard 24-h wait after administration, no irritant unit with 5 pg/mouse ear was seen with either ester. Thus, the IUZ4 values are necessarily larger, and t h e ID5024'~ are expected t o be even higher. In comparison, the IU24 of 3-0-hexadecanoylingenol is 0.1 hg/ear and its ID5Oz4 is 0.050 hg/ear. Although the PKC-binding activity of 38 and 39 and their capability of stimulating Epstein-Barr-Virus synthesis are currently being determined, past correlations would suggest a prognosis t h a t is not favorable.