1,3,4-Thiadiazole-3(2H)-carboxaldehyde, 5-methyl-2-thioxo- → (2R)-3-cyclopentyl-2-{[formyl(tetrahydro-2H-pyran-2-yloxy)amino]methyl}propanoic acid

Participants

Reaction Steps

To a solution of (2R)-3-cyclopentyl-2-{[(tetrahydro-2H-pyran-2-yloxy)amino]methyl}propanoic acid (97.05 g, 358 mmol) in acetone (1.1 L) at room temperature was added 5-methyl-2-thioxo-[1,3,4]thiadiazole-3-carbaldehyde (57.3 g, 358 mmol) (Tetrahedron Lett. 1985, 26, 3703-3706). When the reaction was deemed complete, the acetone was removed in vacuo. The residue was suspended in a mixture of hexanes (320 mL) and methyl-t-butyl ether (180 mL), then sonicated. After 10 min, the white solid (presumably 5-methyl-3H-[1,3,4]thiadiazole-2-thione) was filtered off, and the filtrate was evaporated in vacuo to give (2R)-3-cyclopentyl-2-{[formyl(tetrahydro-2H-pyran-2-yloxy)amino]methyl}propanoic acid as a pale yellow gum (124 g, >100%). NMR shows the product contains a small amount of MTBE and 5-methyl-3H-[1,3,4]thiadiazole-2-thione.

Provenance & Evidence