Acetic Acid → (S)-2-Hydroxymethyl-azetidine-1-carboxylic acid benzyl ester

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Reaction Conditions

Reaction Steps

To a solution of (S)-Azetidine-1,2-dicarboxylic acid 1-benzyl ester (Starting material I-34f, 94 mg, 0.4 mmol) in 0.3 ml dry THF cooled to 0° C. is added dropwise 450 μl of a 1 M solution of borane in THF. The resulting solution is allowed to stir for 1 h at 0° C. and warm up to rt overnight. AcOH (1 ml) and water (1 ml) are then added as well as some saturated NaHCO3 solution in water until pH=9 and no more gas evolution occurs. The resulting aqueous phase is extracted three times with AcOEt. The combined organic phase is washed once with some saturated NaHCO3 solution in water and once with water. The solvents are evaporated in vacuo and the crude oil dried under high vacuum overnight, yielding the title compound (79 mg) in 89% as a colourless oil: tR=0.84 min (LC-3), ESI-MS (pos.): m/z 222.08 [M+H]+; 1H-NMR (CDCl3): δ (ppm) 2.00 (m, 1H, CH2CH2N), 2.22 (m, 1H, CH2CH2N), 3.78-4.01 (m, 5H, CH2N and CH2OH), 4.52 (s, 2H, OCH2Ph), 7.35 (s, 5H, Harom.). Starting material I-35e of the following Table 63 is prepared using a procedure analogous to that described for Starting material I-34e, substituting Starting material I-35f for I-34f.

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