Thiourea → 2-S-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-2-thiopseudourea hydrobromide

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Reaction Steps

2-S-(2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyl bromide (38 g) dissolved in acetone (180 ml) with thiourea (11 g) at 25° C. Batch heated to reflux for a minimum of 2 hrs. Reaction followed by TLC (1:1 petrol/EtOAc. Starting material 0.69, plus multiple peaks below. Product is a salt and therefore is seen on baseline (uv-active)). Batch cooled to R.T. and crystallised, as a white crystalline solid, with the aid of petrol as an anti-solvent (22 g, 49%). M.p=125-127° C. (Lit6 125-128° c.). [α]D22+101 (CHCl3, C=1.1) (Lit6+103). 1HNMR (400 MHz, DMSO). δ=2.0, 2.0, 2.0, 2.0 (sx4, 3H x4, —C(O)CH3×4), 4.1 (dd, J6,612.4 Hz, J5,62.3 Hz, 1H, H-6), 4.2 (dd, J6,612.4 Hz, J5,65.3 Hz, 1H, H-6′), 4.3 (m, 1H, H-5), 5.1 (dd, J3,410 Hz, J2,33.5 Hz, 1H, H-3), 5.2 (t, J3,49.9 Hz, 1H, H-4), 5.4 (dd, J2,33.4 Hz, J1,21.6 Hz, 1H, H-2), 6.3 (d, J1.3 Hz, 1H, H-1), 9.3 (s, 4H, 2×NH2).

Provenance & Evidence