Amino Acids and Peptides in Ball Milling - Ball Milling Towards Green Synthesis: Applications, Projects, Challenges - page 144

Table 6.2 (Continued)
Entry AH H-(AA) x -OR 3 Yield (%) a Boc-AA-NCA or Boc-AA-OSu Mechanosynthesized peptides

15 Boc-Trp-NCA HCl H-Val-Phe-OMe Boc-Trp-Val-Phe-OMe 86

16 Boc-Ile-NCA HCl H-Leu-Pro-OBn Boc-Ile-Leu-Pro-OBn 86

17 Boc-Ile-NCA HCl H-Ile-Ile-OMe Boc-Ile-Ile-Ile-OMe 86

18 Boc-Gly-OSu HCl H-Gly-Phe-OMe Boc-Gly-Gly-Phe-OMe 74

93 f (94) g 19 Boc-Gly-OSu HCl H-Phe-Leu-OBn Boc-Gly-Phe-Leu-OBn

20 Boc-Leu-NCA HCl H-Leu-Leu-Leu-OBn Boc-Leu-Leu-Leu-Leu-OBn 96

96 h (90) i 21 Boc-Gly-OSu HCl H-Gly-Phe-Leu-OBn Boc-Gly-Gly-Phe-Leu-OBn

88 j 22 Boc-Tyr(Bn)-OSu HCl H-Gly-Gly-Phe-Leu-OBn Boc-Tyr(Bn)-Gly-Gly-Phe-Leu-OBn

a Isolated yield. 1.1 o Z o 1.6 mLmg 1 unless otherwise noted.
b 498% diastereomeric excess determined by chiral HPLC.
c Completed in 1 h.
d ML ¼ 28.4 mg mL 1 . Z ¼ 1.1 mLmg 1 .
e ML (milling load) ¼ 188.8 mg mL 1 . Z ¼ of 1.1 mLmg 1 . Completed in 2 h.
f ML ¼ 22.9 mg mL 1 .
g ML ¼ 152.7 mg mL 1 . Completed in 40 min with tBuOAc as the grinding auxiliary.
h ML ¼ 22.2 mg mL 1 , Z ¼ 1.1 mLmg 1 .
i ML ¼ 60.6 mg mL 1 , Z ¼ 1.1 mLmg 1 . Completed in 40 min with tBuOAc as the grinding aid.
j Completed in 1 h.