Table 2.
Influence of the organoboron derivative on the cross-coupling reaction of N-Boc-4-iodo-l-phenylalanine.
Entry | Pd Catalyst | X | Conv (%) a |
---|---|---|---|
1 | Pd-Calix-NS | B(OH)2 | 40 |
2 | Pd-Calix-NS | BF3-K+ | 10 |
3 | Pd-Calix-NS |
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0 |
4 | Pd-Calix-NS |
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98 |
5 | Bulk Pd-Calix |
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<5 |
6 | Pd-PLGA-PEG NPs |
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97b |
7 |
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B(OH)2 | 95c |
aN-Boc-4-iodo-l-phenylalanine (1 equiv.), boronic acid derivatives (3 equiv.), Pd-Calix-NS (0.005 mol%), phosphate buffer (20 mM, pH = 8), 37 °C for 3 h. Conversion determined by 1H NMR analysis of the C-3 methylene signal. b 0.01% Pd, according to reference [30]. c 1 mol% Pd, according to reference [18].