1,3-Propanedithiol → 6,10-Dithia-2-aza-spiro[4.5]decane-2,3-dicarboxylic acid-2-benzyl ester 3-methyl ester

Participants

Reaction Steps

Ketone 2 (250 mg) in CH2Cl2 at 15° C. was treated with 1,3-propanedithiol (100 uL) dropwise followed by BF3OEt2 (119 uL). The mixture was warmed to room temperature and stirred overnight. The reaction was quenched by adding 1 mL potassium carbonate aqueous solution (2 g/30 mL) followed by 321 uL of saturated sodium bicarbonate to adjust to pH 7-8. Washed organics with water, brine, then dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. Purification on a plug of silica gel eluting with toluene→hexane/ethyl ether (2:3→0:1) yielded 200 mg (60%) of desired 6,10-dithia-2-aza-spiro[4.5]decane-2,3-dicarboxylic acid-2-benzyl ester 3-methyl ester 26 as a clear oil. 1H NMR (CDCl3) δ 7.30 (m, 5H), 5.05-5.25 (m, 2H), 4.6 (t, 0.5H), 4.55 (t, 0.5H), 3.8 (s, 1.5H), 3.75 (m, 1H), 3.6 (s, 1.5H), 2.95 (m, 1H), 2.85 (m, 3H), 2.75 (m, 1H), 2.4 (m, 0.5H), 2.35 (m, 0.5H), 2.0 (m, 2H) ppm.

Provenance & Evidence