2-Methylbenzenesulfonic acid → (3r,7s,7As)-4-(3-tert-butyl-7-hydroxy-1-oxo-tetrahydro-pyrrolo[1,2-c]imidazol-2-yl)-naphthalene-1-carbonitrile

Participants

Reaction Steps

A suspension of 30D (40 mg, 0.14 mmol) and pivalaldehyde (30 μl, 0.27 mmol) in a mixture of dry benzene (0.5 ml) and dry pentane (5.0 ml) was refluxed for 20 hr with a Dean-Starke receiver, after which additional pivalaldehyde (30 μl, 0.27 mmol), dry benzene (0.5 ml) and catalytic toluenesulfonic acid was added (Ref: Org. Lett. 2 (18) 2781-2783, (2000)). The reaction mixture was refluxed for another 25 hr, evaporated to dryness and dried in vacuo. Purification using automated flash chromatography (10 g silica gel column, EtOAc/hexane gradient) gave the title compound (single diastereoisomer) as a white foam (40 mg, 81.8%). MS (ES): m/z 350 [M+1]+.

Provenance & Evidence