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. Author manuscript; available in PMC: 2013 Apr 11.
Published in final edited form as: J Am Chem Soc. 2012 Mar 30;134(14):6120–6123. doi: 10.1021/ja301566t

Table 1.

Optimization of peptide scaffold and reaction conditionsa

graphic file with name nihms367971u1.jpg
Entry Catalyst mol% t (h) % conv. 5 6 8
7f Br : 7d Br : 7d,f Br2
1 No catalyst NA 12 71 1.0 : 1.0 : 1.3b
2a N,N-dimethylacetamide 100 12 68 1.0 : 1.0 : 1.8b
2b N,N-dimethylacetamide 7100 16 64 1.0 : 1.5 : 2.9b
3 Boc-Asn(Me2)-DAla-DAla-OH (10) 100 2 97 1.0 : 6.8 : 2.6b
4 Boc-DAsn(Me2)-DAla-DAla-OH (11) 100 2 90 1.0 : 4.9 : 1.8b
5 Boc-Gln(Me2)-DAla-DAla-OH (12) 100 2 99 1.0 : 4.0 : 9.3b
6 Boc-DGln(Me2)-DAla-DAla-OH (13) 100 2 99 1.0 : 3.0 : 3.4b
7 Boc-Leu-DAla-DAla-OH (14) 100 12 60 1.0 : 5.7 :2.5b
8a Boc-Asn(Me2)-DAla-DAla-OH (10) graphic file with name nihms367971t1.jpg 100 1.5 98 1.0 : 14.6 : 2.8c
8b 200 1.5 99 1.0 : 19.0 : 6.0c
8c 50 2 97 1.0 : 3.4 : 1.1c
8d 25 1.5 83 1.0 : 1.9 : 0.7c
9 Boc-Leu-DAsn(Me2)-DAla-OH (15) 200 12 96 1.0 : 6.5 : 2.7c
10 Boc-Leu-DAla-DAsn(Me2)-OH (16) 200 12 85 1.0 : 3.5 : 1.0c
11 Boc-Asn(Me2)-DAla-DAla-OH (10) 100 1.5 16 1.0 : 10.5 : 0.9d
12 Boc-Leu-DAla-DAsn(Me2)-OH (16) 100 1.5 12 1.0 : 3.5 : 1.6d
a

Ratios were measured by HPLC at 280 nm wavelength.

b

2.0 equiv of NBP, 250 μL of water, 50 μL of MeOH, 8 μmol of 4.

c

2.0 equiv of NBP, 1000 μL of water, 200 μL of MeOH, 8 μmol of 4.

d

50 mol% NBP, 0.033 mmol of 4.