Methanesulfonyl chloride-dimethylaminopyridine

Scheme 25. Reagents and conditions (a) R sAI, Cul-2 LiCI, THF, 0°C (b) PivCI, py (c) 4-dimethylaminopyridine (DMAP) (3 equiv.), NaNa (20 equiv.), methanesulfonyl chloride (MsCI) (3 equiv.), RT then DMSO 3 h (d) UAIH4 (e) B0C2O, EtgN, CH2CI2.

Methanesulfonyl chloride-4-Dimethylaminopyridine. An effective reagent for dehydration (1) is prepared by stirring MsCl (2.5 equiv), DMAP (1.25 equiv.), and HzO (1 equiv.) in CH2C12 (13 ml.) for 2-3 days at 25°. The water is essential for hydrolysis of MsCl to MsOH and HC1. 

Another useful method to convert thioureas into carbodiimides involves their reaction with reactive chlorine compounds, such as SOCI2, SO2CI2, SCI2 or S2CI2, The use of the sulfur chlorides involves chloroformamidines as intermediates (see Section 2.2.6). The reaction of thioureas 11 with methanesulfonyl chloride in methylene chloride in the presence of triethylamine/DMAP (4-dimethylaminopyridine) at room temperature produces carbodiimides 12 in 85-100% yield... 

Handling, Storage, and Precautions effective even after 6 months for handling the components, see methanesulfonyl chloride and 4-dimethylaminopyridine. 

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