Abstract
LiNTf2 in the reaction of lactones with amines is able to activate cyclic esters towards
ring opening, thus leading to clean open-chain amides under mild conditions and using
a stoichiometric amount of amine. The generality of the method was demonstrated by
a range of selected lactones and amines.
Key words
amides - ring opening - Lewis acids - lactones - catalysis
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General Procedure for Lactone Aminolysis; Synthesis of
N
-Allyl-4-hydroxybutyramide(3) : To a solution of γ-butyrolactone (1 ; 1 equiv) and allylamine (2 ; 1 equiv) in anhyd CHCl3 (0.5 mL/mmol) was added under a nitrogen atmosphere LiNTf2 (0.5 equiv). The mixture was stirred in a sealed vial at 85 °C (oil bath) for 40
h, then it was washed with a sat. NaHCO3 solution, and the organic phase was evaporated to give the title product as a clean
viscous oil (99%). 1 H NMR (200 MHz, CDCl3 ): δ = 6.62 (br, 1 H, NH), 5.73-6.03 (m, 1 H, =CH), 5.04-5.23 (m, 2 H, =CH2 ), 4.02 (br, 1 H, OH), 3.88 (t, J = 5.5 Hz, 2 H), 3.72 (t, J = 5.5 Hz, 2 H), 2.40 (t, J = 6.2 Hz, 2 H), 1.79-1.96 (m, 2 H). 13 C NMR (50 MHz, CDCl3 ): δ = 178.2 (s, C=O), 137.1 (d, =CH), 119.4 (t, =CH2 ), 65.1 (t, CH2 ), 45.4 (t, CH2 ), 36.4 (t, CH2 ), 31.5 (t, CH2 ). MS (EI, 70 eV): m /z (%) = 143 (1) [M+ ], 99 (28), 84 (10), 69 (14), 57 (100). Anal. Calcd for C7 H13 NO2 : C, 58.72; H, 9.15; N, 9.78. Found: C, 58.70; H, 9.14; N, 9.76.