Basanagoud S. Patil

Synthesis of Fmoc-amino acid chlorides assisted by ultrasonication, a rapid approach

The chloride derivatives of all common Fmoc-amino acids lacking polar side chains as well as a number of benzyl based side chain protection have been prepared using the corresponding amino acid and thionyl chloride assisted by ultrasound has been described. The protocol is simple, efficient and rapid. All the acid chlorides prepared have been obtained in good yield and purity.

Mw-enhanced high-speed deprotection of boc group using p-TsOH and concommitant formation of N-Me-amino acid benzyl ester p-TsOH salts

Abstract A high‐speed, complete deprotection of Boc group from Boc amino acids and protected peptide esters employing p‐TsOH in toluene under microwave irradiation 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 N α‐Fmoc and N α‐Z 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.

Microwave assisted Wolff rearrangement: A facile method for the synthesis of Fmoc-β-amino acids

The Wolff rearrangement of α-diazoketones, derived from Fmoc-α-amino acids, under no base conditions on exposure to microwave irradiation for 40 to 60 sec to Fmoc-β-amino acids with retention of configuration in good yield (91–95%) is described.

Homologation of α-amino acids to β-amino acids using Boc2O

The use of Boc2O as a coupling agent in the homologation of N-urethane protected-α-amino acid to its β-homomers by the Arndt–Eistert method is described. The homologation gives good yields without racemization. The use of Boc2O as a coupling agent not only allows the easy scale up of the process but also it is cost effective.

Synthesis of β-Amino Acids: 2-(1H-Benzotriazol-1-yl)-1,1,3,3-tetramethyluronium Tetrafluoroborate (TBTU) for Activation of Fmoc-/Boc-/Z-α-Amino Acids

Abstract A new and efficient method for the homologation of urethane protected α-amino acids to its β-homomers by the Arndt-Eistert method using TBTU as a coupling agent is described. Several Fmoc-/Boc-/Z-protected α-amino diazoketone derivatives have been obtained as crystalline solids in good yield. The method is found to be rapid and stereospecific.

Synthesis of peptidyl ureas employingO-pentafluorophenyl-(9-fluorenylmethoxycarbonylamino)methyl carbamate derivatives

A rapid and efficient method for the synthesis of peptidyl ureas employingO-pentafluoro phenyl-(9-fluorenylmethoxycarbonylamino)methyl carbamates has been described.

Microwave assisted facile synthesis of amino acid benzyl ester p-toluenesulfonate and hydrochloride salts

A simple method for the synthesis of several amino acid benzyl esterp-toluenesulfonate salts from the corresponding amino acid and benzyl alcohol in presence ofp-toluenesulfonic acid accelerated with microwave irradiation is described. Under similar condition, the amino acid benzyl ester hydrochloride salts have also been obtained by using thionyl chloride instead ofp-toluenesulfonic acid in good yield and purity.

Synthesis of Peptidyl Ureas Using p‐Nitrophenyl‐(9‐fluorenylmethoxy Carbonylamino)methyl Carbamate Derivatives

Abstract An efficient synthesis of p‐nitrophenyl‐(9‐fluorenylmethoxy carbonylamino) methyl carbamates using isocyanates derived from Fmoc‐amino acid azides and p‐nitrophenol in presence of an equimolar quantity of N‐ethyldiisopropyl amine is described. All the carbamates have been isolated as crystalline solids and are fully characterized. Further, their utility for the synthesis of dipeptidyl ureas has been demonstrated.