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

Wolff rearrangement of <i>N^{<img src='/image/spc_char/alpha.gif' border=0>}</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^{<img src='/image/spc_char/alpha.gif' border=0>}</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

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="State"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Synthesis of a modified peptide fragment analog Val-Tyr (<i>P</i>)-Val-Ala-Ala-OH of cAMP protein kinase regulatory sub unit type II employing Fmoc chemistry </smarttagtype></smarttagtype>

1747-1752The synthesis of new peptide fragment analog (Val-Tyr(P)-Val-Ala-Ala-OH) incorporating Tyr into the phosphorylation site of the cAMP protein kinase regulatory sub unit type II in place of Ser (Val-Ser(P)-Val-Ala-Ala-OH) has been described. The phosphopentapeptide fragment is prepared by Fmoc chemistry employing the global phosphorylation method. The yield (68%) as well as purity of the final peptide is satisfactory. The peptide is fully characterized by HPLC, NMR and mass spectral data