13 research outputs found
MW-enhanced high-speed deprotection of Boc group using p-TsOH and concomitant formation of N-Me-amino acid benzyl ester p-TsOH salts
A high-speed, complete deprotection of Boc group from Boc (Boc = tert-butoxycarbonyl) amino acids and protected peptide esters employing p-TsOH in toluene under microwave irradn. is found to be complete in 30 s. The deprotection can be carried out in methanol and acetonitrile also. Under the present conditions, C-peptide benzyl esters and O-benzyl ethers have been found to be stable. This has permitted us to carry out the synthesis of [Leu]enkephalin employing the Boc/Bzl-group strategy. Further more, it has been found that both Nα-Fmoc (Fmoc = 9-fluorenylmethyloxycarbonyl) and Nα-Z (Z = benzyloxycarbonyl) groups are completely stable. The present conditions can be extended for the concomitant removal of the Boc group and the formation of C-benzyl amino acid esters as well. This has been utilized for the synthesis of N-Me amino acid benzyl esters starting from Boc-N-Me amino acids in a single step
Wolff rearrangement of Nα-Boc-/Z-protected amino diazoketones to the corresponding β-amino acids under microwave irradiation
The Wolff rearrangement of Nα-Boc-/Z-protected amino diazoketones in the presence of silver benzoate under microwave irradn. is described. The reaction is found to be rapid, efficient and complete. It results in the isolation of Boc-/Z- protected-β-amino acids in good purity as well as yield
Synthesis of peptidyl ureas using p-nitrophenyl (9-fluorenylmethoxycarbonylamino)methylcarbamate derivatives
Carbamates Fmoc-NHCHRNHCO2C6H4NO2-p (Fmoc is 9-fluorenylmethoxycarbonyl, R is an amino acid side chain) were prepd. using isocyanates derived from Fmoc-amino acid azides and p-nitrophenol in the presence of an equimolar quantity of N-ethyldiisopropylamine. The carbamates were coupled with amino acid ester hydrochlorides to afford dipeptidyl ureas
A rapid and convenient synthesis of <i>α </i>and <i>β </i>forms of acetylated derivatives of sugars under microwave irradiation
1288-1291In a novel
method, the synthesis of α and β forms of penta as well as octa
acetyl derivatives of several sugars under microwave irradiation with improved
yields is described
A rapid synthesis of dipeptidyl urea acids employing <i>p</i>-nitrophenyl-(9- fluorenylmethoxycarbonylamino)methyl carbamates
1721-1728<span style="font-size:14.0pt;line-height:
115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">A rapid and efficient method for the synthesis of dipeptidyl urea acids
employing p-nitrophenyl-(9-fluorenylmethoxy-carbonylamino) methyl carbamates
as coupling agents has been described. The protocol is simple and efficient.
All the compounds made have been obtained in good yields. They have been fully characterized
by 1H and 13C NMR and mass spectra.</span
A Rapid Synthesis of Dipeptidyl Urea Acids Employing p-Nitrophenyl-(9-fluorenylmethoxycarbonylamino)methyl Carbamates.
1721-1728<span style="font-size:14.0pt;line-height:
115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">A rapid and efficient method for the synthesis of dipeptidyl urea acids
employing p-nitrophenyl-(9-fluorenylmethoxy-carbonylamino) methyl carbamates
as coupling agents has been described. The protocol is simple and efficient.
All the compounds made have been obtained in good yields. They have been fully characterized
by 1H and 13C NMR and mass spectra.</span
Wolff rearrangement of <i>N<sup><img src='/image/spc_char/alpha.gif' border=0> </sup></i>- Boc-/Z-protected aminodiazoketones to the corresponding <i>β</i>-amino acids under microwave irradiation<b style=""></b>
2611-2613The Wolff rearrangement of
N-Boc-/Z-protected aminodiazoketones in the
presence of silver benzoate under microwave irradiation is described. The
reaction is found to be rapid, efficient and complete. It results in the
isolation of Boc-/Z- protected-β-amino acids in good purity as
well as yield
<i>N<sup><img src='/image/spc_char/alpha.gif' border=0> </sup></i>-Fmoc-Peptide azides: Synthesis, isolation, characterization and utility in the extension of peptide chains
1853-1858Syntheses of N-Fmoc-peptide
azides employing acid chloride as well as mixed anhydride methods have been carried
out. The resulting Fmoc-peptide azides prepared have been isolated as solids in
good yield (75-92 %) and are found to be analytically pure. Further, long shelf
life of N-Fmoc-peptide azides makes them useful in the
extension of peptide chains. </b