Synthesis of unnatural selenocystines and beta-aminodiselenides via regioselective ring-opening of sulfamidates using a sequential, one-pot, multistep strategy.

A variety of N-alkyl-beta-aminodiselenides have been synthesized in high yield from sulfamidates under mild reaction conditions using potassium selenocyanate and benzyltriethylammonium tetrathiomolybdate ([BnNEt(3)](2)MoS(4)) in a sequential, one-pot, multistep reaction. The tolerance of multifarious protecting groups under the reaction conditions is discussed. The methodology was successfully extended to the synthesis of selenocystine, 3,3'-dialkylselenocystine, and 3,3'-diphenylisoselenocystine and their direct incorporation into peptides.

One-pot protection and activation of amino acids using pentafluorophenyl carbonates.

Protection of the amino group and activation of the carboxylic acid groups are the most important steps associated with any peptide synthesis protocol; hence, a one-pot process to achieve these is highly desirable. A possible strategy is to use pentafluorophenyl carbonates to simultaneously protect the amino group as a carbamate derivative and activate the carboxylic acid group as a pentafluorophenyl ester. A detailed study is carried out to understand the scope and limitations of this method using five different pentaflurophenyl carbonates. The efficiency of these one-pot reactions depends largely on the nature of the pentafluorophenyl carbonates and also on the nature of the amino acids. Electron deficient and sterically less demanding carbonates reacted faster than the others, whereas amino acids with longer aliphatic side chains gave better yields than more polar amino acids.