Efficient microwave assisted access to chiral O-(α-protected-aminoacyl)steroids

Chiral Acylation with N-(Protected α-Aminoacyl)benzotriazoles for Advantageous Syntheses of Peptides and Peptide Conjugates

“…In addition, phenolic steroids were prepared (i) by the active ester method, 107 or (ii) using acetic anhydride 108 alone or together with (a) pyridine over basic alumina under microwave irradiation, 109 (b) catalytic amounts of niobium(V) chloride, 110 Table 14). 37 In addition, the methodology can be easily extended to more sterically hindered systems by incorporating dipeptides and steroids, with complete retention of the original chirality.…”

Microwave‐Assisted Solid‐Phase Peptide Synthesis Utilizing N‐Fmoc‐Protected (α‐aminoacyl)benzotriazoles

“…The crude yields of hexapeptide 6 and heptapeptide 7 were 73% and 65%, respectively, with purities of ca 50% following HPLC. The Met‐ or Trp‐containing peptides in 4–7 were cleaved from the resin using Reagent R (TFA:thioanisole:EDT:anisole = 90:5:3:2). Characterization of the purified compounds 3 , 4 , 5 , 6 , and 7 by HPLC revealed complete retention of configuration (see Supplementary Material).…”

“…Acylbenzotriazoles (1–3) are easily prepared, nonhydroscopic, chirally stable analogues of acid halides that are relatively insensitive to water (4). Solution‐phase peptide coupling reactions of N ‐protected( α ‐aminoacyl)benzotriazoles with unprotected amino acids proceed with minimal epimerization in partially aqueous solution under mild conditions (5) and allow the preparation of di‐, tri‐, and tetrapeptides (4–6) as well as O ‐aminoacylation of hydroxysteroids (7), terpenes (8), and C ‐acylation of activated heterocycles (9).…”

Design, synthesis and stimuli responsive gelation of novel stigmasterol–amino acid conjugates

“…In the past there have been reported several steroid-amino acid conjugates which were shown as effective organogelators. However, in most of these cases either bile acids [17,18] or cholesterol [19][20][21][22][23] have been utilized as the steroidal unit. In this work we used the less common stigmasterol.…”