12-DEOXYPHORBOL 13-PHENYLACETATE synthesis

Yield:58821-98-0 87%

Reaction Conditions:

in ethyl acetate;benzene at 20; for 0.75 h;UV-irradiation;

Steps:

10

Example 10; Formation of Cyclopropane Ring Structure; A solution of S10 (5.4 mg, 10.9 μmol) in benzene/EtOAc (1:1, 1 mL) was stirred at room temperature in a disposable glass vial flushed with argon. The solution was irradiated with UV light (300 nm) using a Rayonet photochemical reactor at room temperature for 45 min. until TLC indicated complete consumption of the starting material. The reaction mixture was concentrated under reduced pressure, and subjected to flash (100% EtOAc, ID 8 mm, 1 g silica) to give 12-deoxyphorbol-13-phenylacetate (DPP) as a white powder (4.4 mg, 87%). The product was characterized by:TLC R_f=0.45 (100% EtOAc), one black spot in p-anisaldehyde (visible under UV lamp)[α]_D²³=5+35.7° (c 0.44, CHCl₃)¹H NMR (500 MHz, CDCl₃ after D₂O shake): δ 7.57 (br s, 1H, C1-H), 7.35-7.24 (m, 5H, Ar-H), 5.63 (d, J=4.5 Hz, 1H, C7-H), 4.02 (d, J=12.8 Hz, 1H, C20-H), 3.94 (d, J=12.8 Hz, 1H, C20-H) 3.62 (d, J=14.7 Hz, 1H, CH2Ph), 3.58 (d, J=14.7 Hz, 1H, CH2Ph), 3.24 (dd, J=2.7, 2.7 Hz, 1H, C10-H), 2.94 (m, 1H, C8-H), 2.50 (d, J=19 Hz, 1H, C5-H), 2.43 (d, J=19 Hz, 1H, C5-H), 3.07 (dd, J=7.0, 14.0 Hz, 1H, C12-H), 1.99-1.95 (m, 1H, C11-H), 1.76 (dd, J=1.4, 2.9 Hz, 3H, C19-H), 1.54 (dd, J=11.1, 14.5 Hz, 1H, C12-H), 1.03 (br s, 6H, C16-H and C17-H), 0.86 (d, J=6.5 Hz, 3H, C18-H), 0.75 (d, J=5.4 Hz, 1H, C14-H) ppm.¹³C NMR (125 MHz, CDCl₃): δ 209.4, 173.6, 161.4, 139.8, 133.2, 132.8, 130.2, 129.3 (2), 128.6 (2), 127.3, 76.1, 73.7, 68.2, 64.0, 55.7, 41.7, 39.1, 38.6, 36.3, 32.4, 31.7, 23.0, 22.9, 18.5, 15.3, 10.1 ppm.FT-IR (thin film): ν 3399, 2921, 1707, 1625, 1455, 1246, 1133, 1015 cm^-1.HRMS: Calcd.: (for C₂₈H₃₄O₆Na): 489.2253, Found: 489.2256

References:

US2009/187046,2009,A1 Location in patent:Page/Page column 15