Carbamates Experimental Procedures

Wang resin bound 4-nitrophenyl carbonate is a convenient intermediate for the attachment of amines to polystyrene as carbamates (see Experimental Procedure 14.2). Aliphatic amines [82-87], ammonia [88], and amino acids [89] react exothermically with this support, whereas anilines generally require catalysis and/or long reaction times (Entry 3, Table 14.7). For the immobilization of anilines as carbamates, Wang resin derived chloroformate [90-92] generally leads to better results than resin-bound 4-nitrophenyl carbonates. Amidines also react with polystyrene-bound 4-nitrophenyl carbonates to yield /V-alkoxycarbonyl amidines (Section 3.9 [93-95]). Support-bound alkoxycarbonyl hydrazines can be prepared by treating polystyrene-bound phenyl carbonates with hydrazine [96-98]. 

Experimental Procedure 14.2 Attachment of piperazine to Wang resin as carbamate [99 ... 

The preparation of carbonates is mechanistically closely related to the synthesis of carbamates, and similar reagents can be used for this purpose (Table 14.10). Resin-bound alcohols can be directly converted into carbonates by treatment with a chloro-formate (see Experimental Procedure 14.2), in two steps by activation with phosgene or a synthetic equivalent thereof followed by reaction with an alcohol in the presence of a base, or by treatment of a resin-bound alcohol with carbon dioxide and an alkyl halide under basic reaction conditions [125]. Thiocarbonates can be prepared from... 

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