A facile synthesis and crystallographic analysis of N-protected β-amino alcohols and short peptaibols

Abstract

A facile, efficient and racemization-free method for the synthesis of N-protected β-amino alcohols and peptaibols using N-hydroxysuccinimide active esters is described. Using this method, dipeptide, tripeptide and pentapeptide alcohols were isolated in high yields. The conformations in crystals of β-amino alcohol, dipeptide and tripeptide alcohols were analysed, with a well-defined type III β-turn being observed in the tripeptide alcohol crystals. This method is found to be compatible with Fmoc-, Boc- and other side-chain protecting groups.

Small molecule diselenide additives for in vitro oxidative protein folding

“…1 18.88 mmol) in dry THF (~40 mL) at 0 o C and stirred at same temperature for 1 h. Then filtered using THF (3 x 4 mL) to remove the precipitated urea by-product. 6 NaBH 4 (1.30 g, 34.33 mmol) in water (8 mL) was added to activated -ONSu ester in THF at 0 o C. After 10 min, 0.5 N HCl (40 mL) was added to quench the unreacted NaBH 4 .…”

Microwave assisted chemoselective organocatalytic peptide alcohol synthesis from C-terminal amide

“…We observed two new peaks at 52.3 and 41.7 (b and c), which corresponds to the methyl ester of benzoylglycine (II) in place of a. Finally, ethanolamine was added to the reaction mixture, and the 13 C NMR spectrum was recorded aer 90 min. We observed b and c peaks to be replaced by three new peaks at 42.1, 43.3, and 60.9 ppm (d, e and f), which correspond to the carbons of the expected product (IV).…”

“…Peptaibols or Aib containing C-terminal peptide alcohols have been synthesized using a variety of methods such as from C-terminal carboxylic acids using mixed anhydrides, 9 acid uorides, 10 acid chlorides, 11 1-hydroxybezotriazole esters, 12 1-succinimidyl esters, 13 and coupling reagents, e.g. DCC/ HOBT, 14 EDC/HOBT, 15 HATU, 2a DEPBT, 16 or activated esters.…”

“…It worked, but low (30%) yield of the product (benzoylglycylglycine methyl ester, Bz-Gly-Gly-OMe) was obtained aer 15 h under microwave The plausible mechanism of the reaction involves an intermolecular N to O acyl migration (I to II, Scheme 3) followed by the intramolecular O to N acyl migration (III to IV). To illustrate the reaction mechanism we have recorded 13 C NMR spectrum of benzoylglycinamide (I) and observed the peak at 42.5 ppm (a), which corresponds to the -CH 2of benzoylglycinamide. We initiated the reaction with benzoylglycinamide and PTSA in absence of ethanolamine in methanol at 80 C and recorded a 13 C NMR spectrum of the reaction mixture aer 6 min.…”

“…To illustrate the reaction mechanism we have recorded 13 C NMR spectrum of benzoylglycinamide (I) and observed the peak at 42.5 ppm (a), which corresponds to the -CH 2of benzoylglycinamide. We initiated the reaction with benzoylglycinamide and PTSA in absence of ethanolamine in methanol at 80 C and recorded a 13 C NMR spectrum of the reaction mixture aer 6 min. We observed two new peaks at 52.3 and 41.7 (b and c), which corresponds to the methyl ester of benzoylglycine (II) in place of a.…”