Yield:26843-47-0 95%

Reaction Conditions:

with 5%-palladium/activated carbon;hydrogen in ethyl acetate at 20; under 1034.32 Torr;Inert atmosphere;

Steps:

2; 4; 5 Synthesis of Anhydride 6 from the Hydrogenation of Anhydride 5

Diels Alder adduct (Anhydride 1) (9.269 g, 0.05202 moles) dissolved in 100 mL ethyl acetate and 5 wt % Palladium on carbon (0.250 g) were added in Fisher porter bottle and purged with nitrogen. The reactor was then charged with H₂ (20 psi) and allowed to stir at room temperature while monitoring the reaction pressure. When the reaction pressure had dropped to 5 psi the system was recharged with H₂ (20 psi) and the process repeated over a period of 1 day until consumption H₂ had ceased. The reaction mixture was centrifuged and the product mixture isolated by decantation. The spent Pd/C catalyst was washed (twice) with 25 mL aliquots of ethyl acetate and all filtrate portions combined and reduced to a solid under dynamic vacuum at room temperature to yield an off-white powder of Anhydride 2, 8.91 g (95.0% yield). ¹H NMR (700 MHz, CDCl₃, 25° C.): δ=1.58 (s, 4H, CH₂ cyclohexane), 1.62 (dd, J=7.7 Hz, 2H, CH₂ cyclohexane), 1.74 (dd, J=7.7 Hz, 2H, CH₂ cyclohexane), 2.24-2.26 (m, 2H, -CH- cyclohexane), 3.12 (dd, J=3.5 Hz, 2.1 Hz, 2H, -CH-CO). ¹³C NMR (700 MHz, CDCl₃, 25° C.): δ=21.37 (CH₂ cyclohexane), 24.12 (CH₂ cyclohexane), 25.98 (methine cyclohexane), 44.25 (-CH-CO) 173.98 (CO). IR: 2946 cm^-1, 2875 cm^-1 (CH stretching), 1858-1745 cm^-1 (C═O stretching), 1480-1316 cm^-1 (CH bending), 1273-1196 cm^-1 (C-O stretching), 1076-700 cm^-1 (CH out of plane bending). LC-MS: m/z 181.08 (M⁺), 167, 153, 139, 135, 107, 79.

References:

US2013/324688,2013,A1 Location in patent:Paragraph 0035; 0041; 0044; 0087-0088