New Family of Base- and Nucleophile-Sensitive Amino-Protecting Groups. A Michael-Acceptor-Based Deblocking Process. Practical Utilization of the 1,1-Dioxobenzo[b]thiophene-2-ylmethyloxycarbonyl (Bsmoc) Group

Amino Acid-Protecting Groups

“…This is particularly relevant in the synthesis of polyproline peptides in which the use of the Fmoc group leads to deletions caused by premature Fmoc removal by the secondary amine of Pro whereas no Pro insertions are observed when Nsc is used, 67 Nsc is also important in automated SPS, where amino acid solutions are stored for a long time. Further advantages of the Nsc vs. Fmoc group are that the formation of the olefin-amine adduct 70 It is the most important of a series of protecting groups that are removed via a Michael addition.…”

“…back alkylation by the β-elimination by-product is prevented because the deblocking event is also a scavenging event; 70 (ii) base-catalyzed side reactions, such as aspartimide formation, are minimized as a result of lower concentrations of secondary amines 70,73 and (iii) the method can be applied to the rapid continuous solution synthesis technique. 73,74 Bsmoc-amino acids have been used to synthesize several model peptides in which the Bsmoc group was removed with 2-5 % piperidine in DMF, 70 and have shown better performance than Fmoc amino acids in difficult couplings such as Aib-Aib.…”

“…73,74 Bsmoc-amino acids have been used to synthesize several model peptides in which the Bsmoc group was removed with 2-5 % piperidine in DMF, 70 and have shown better performance than Fmoc amino acids in difficult couplings such as Aib-Aib. 41 Furthermore, the Bsmoc group can be selectively removed with 2% of tris(2-aminoethyl)amine (TAEA) in DCM in the presence of Fm esters.…”

Microwave Assisted Alcoholysis of Isocyanates Derived from Nα-[(9-fluorenylmethyl)oxy]carbonyl Amino Acids: Synthesis of N-Fmoc-N1-Z-/Boc-/Alloc-/Bsmoc-gem-diamines

“…Both preparation as well as the isocyanates derived from N a -Fmoc-a-amino acids as coupling agents for the synthesis of peptidyl ureas was demonstrated to be completely free from racemization (Patil and Sureshbabu, 2003). This paper demonstrates the synthesis of N-Fmoc-N 1 -urethane (Z-/Boc-/Alloc-/Bsmoc) (Carpino et al, 1997(Carpino et al, , 1999 protected gem-diamines and their utility in the synthesis of retro-inverso peptides.…”

Synthesis of 1,1-Dioxobenzo[b]thiophene-2-ylmethyloxycarbonyl (Bsmoc) Protected N-Methyl Amino Acids by Reduction of Bsmoc-5-Oxazolidinones and Their Use in Peptide Synthesis

“…The key difference of this invention is the mode of cleavage mechanism through Michael-like attack of base on , unsaturated sulfones [19] followed by elimination of CO 2 and amino component (Scheme 1). As Bsmoc group can be effectively cleaved with very low concentration of a weak base, its usage can circumvent several base catalyzed side reactions.…”