Reaction Steps
Pd(O)-catalyzed deprotection of the allyl ester proceeded as follows to yield 2-Decanoylamino-pentanedioic acid 1-benzyl ester (8). To a solution of 752 mg (1.74 mmol) of 2-decanoylamino-pentanedioic acid 7 in 10 mL of CH2Cl2 was added 100 mg (0.087 mmol) of tetrakistriphenylphosphine Pd(O) followed by 0.52 mL (1.9 mmol) of tributyltin hydride. After 15 min, the reaction mixture was quenched with 10 mL of a 10% HCl solution. The aqueous layer was reextracted with 15 mL of CH2Cl2 and the organic layer dried (Na2SO4) , concentrated in vacuo, and chromatographed on SiO2 (Hexanes/EtOAc, 9:1) to provide 545 mg (79.9%) of 8 as a thick oil: [α]D +2.8° (c 1.2, CHCl3, 21° C.); IR (neat) 3351, 3064, 2995, 2852, 1738, 1712, 1657, 1536, 1454, 1380, 1364, 1265, 1209, 1183, 1121, 739 cm-1 ; 1H NMR δ 10.9-10.7 (bs, 1 H), 7.22 (s, 5 H), 6.58 (d, 1 H, J=7.8 Hz), 5.09 (s, 2 H), 4.63 (dd, 1 H, J=8.1, 12.9 Hz), 2.4-2.25 (m, 2 H), 2.2-2.1 (m, 3 H), 2.0-1.9 (m, 1 H), (m, 6 H), 1.53 (t, 2 H), J=6.6 Hz), 1.19 (bs, 12 H), 0.81 (t. 3 H, J=6.0 Hz); 13C δ 176.9, 174.0, 171.8, 134.9, 128.5, 128.4, 128.1, 67.3, 51.4, 36.2, 31.7, 29.9, 29.3, 29.2, 29.1, 27.0, 25.5, 22.5, 14.0; MS (El) m/z (relative intensity) 391 (54), 373 (62), 279 (13), 256 (19), 178 (27), 178 (23), 155 (13), 146 (6), 130 (7), 102 (100); HRMS (El) m/z calculated for C22H33NO5 :391.2358, found: 391.2350.
