[N-:1]=[C:2]=S.C(Cl)(Cl)=S.NC(N)=S.[CH:12]1([N:18]=[C:19]=[N:20]C2CCCCC2)C[CH2:16][CH2:15][CH2:14][CH2:13]1.C([O-])(O)=O.[Na+]>ClCCl.C1COCC1>[NH2:20][C:19]1[NH:18][C:12]2[CH:13]=[CH:14][CH:15]=[CH:16][C:2]=2[N:1]=1
A mixture of an isothiocyanate (prepared by reacting the corresponding amine with thiophosgene) and a suitably substituted phenylenediamine in dry dichloromethane was stirred at rt overnight and evaporated to dryness. The resulting thiourea was then purified by e.g. column chromatography or reacted further as crude material. Thus, the thiourea was dissolved in THF, added a coupling reagent such as dicyclohexylcarbodiimide (DCC), and stirred at reflux temperature overnight. Aqueous NaHCO3 was added and the solution extracted with EtOAc. The combined organic phases were dried (MgSO4), filtered and concentrated in vacuo to give the crude 2-aminobenzimidazole which was subsequently purified by column chromatography or preparative LCMS.
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