Chlorosulfonyl isocyanate , Burgess

Preparation of the reagent [70] A solution of PEG monomethyl ether 89 (MW = 750 5.88 g, 7.8 mmol) in benzene (20 mL) was dried azeotropically for 24 h in an apparatus fitted with a Dean-Stark trap and subsequently added dropwise to a solution of chlorosulfonyl isocyanate (88) (1.10 g, 7.8 mmol) in dry benzene (20 mL). The mixture was stirred at room temperature for 1 h, then concentrated to dryness. A solution of this residue in benzene (35 mL) was added dropwise to a solution of triethylamine (2.5 mL, 17.3 mmol) in benzene (15 mL). The mixture was stirred for 30 min at room temperature, then filtered, and the solid was dried to yield polymer-supported Burgess reagent 91 (6.2 g, 82%). 

The formation of Burgess-type reagents (75) from chlorosulfonyl isocyanate (CSI) has recently been disclosed. The one-pot synthesis works well with primary, secondary, and tertiary alcohols and amines containing an active hydrogen.21... 

Acidic reagents seem to offer milder conditions. Dehydration reactions forming cyanides can be performed with phosgene [1049-1052], diphosgene [1053-1055], triphosgene [1056], phenyl chloroformate [1057], oxalyl chloride [1058, 1059], tri-chloroacetyl chloride [1060-1062], acetic anhydride [1063-1074], TFAA [1075-1082], phosphorus oxides [1083-1088], phosphorus oxychloride [1089-1098], phosphorus pentachloride [1099], triphenylphosphine/haloalkanes [1100-1103], thionyl chloride [1104-1118], p-tosyl chloride [1119-1124], triflic anhydride [1125-1127], chlorosulfonyl isocyanate [1128], the Burgess reagent [1129], phenyl chloro-thionoformate [1130], cyanuric chloride [1131-1134], carbodiimides [1135, 1136], CDC [1137], PyBOP [1138], AlCU/Nal [1139], and acetonitrile/aldehyde [1140], and by pyrolysis [1141]. 

The Burgess reagent is a chlorine-free advancement of chlorosulfonyl isocyanate (see also Section 4.5.1), in which the two active sites are reacted with triethyl-amine and methanol, respectively, forming appropriate residues. This achieves the required level of reactivity and the right degree of selectivity, and thus enables consistent reaction mechanisms. 

Preparative Method although the Burgess reagent is commercially available, it can be easily sjmthesized in two steps the reaction of anhydrous methanol with Chlorosulfonyl Isocyanate followed by the addition of Triethylamine affords the... 

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