A new polymer-supported reagent for the Fmoc-protection of amino acids

N-Urethane protection of amines and amino acids in an ionic liquid

“…aniline (2a) was treated with 9-uorenylmethyloxycarbonyl chloride (Fmoc-Cl) (1) (1 : 1 mmol) in 1 mL of [Bmim] [BF 4 ]. 16 Therefore, we decided to use a commercially available reagent with a different leaving group such as the 9-uorenylmethyl succinimidyl carbonate (Fmoc-OSu) that has shown to be a more shelf-stable carbonate. TLC analysis of the reaction mixture showed aer only 1 minute the disappearance of the FmocCl and the formation of a new spot on the TLC plate that travels with the solvent front and assigned to dibenzofulvene: in this case, it is more likely that the ionic liquid assists the belimination to give quickly the dibenzofulvene and liberation of the chlorine ion.…”

“…3 Hz, 2H, NHCH 2 CH 2 ), 3.11-3.14 (m, 2H, NHCH 2 CH 2 ), 4.21 (m, 1H, CHFmoc), 4.27 (d, J ¼ 6.9 Hz, 2H, CH 2 Fmoc), 6.65 (d,J ¼ 8.4 Hz,2H, ArH), 6.95 (d, J ¼ 8. EIMS m/z (%) 237 (3, M+c), 178 (8), 134 (12), 108 (45), 91 (100), 79 (21), 77 (16), 70 (35), 65 (7). 13 C-NMR: (75 MHz,42.6,47.3,67.9,115.5,120.5,121.9,127.7,129.4,129.8,137.9,139.8,142.9,156.0,157.6 75 (broad s,1H,NH),4H,ArHFmoc), 7.59 (d, J ¼ 6.9 Hz, 2H, ArHFmoc), 7.80 (d, J ¼ 6.9 Hz, 2H, ArHFmoc).…”

New Polymer-Supported Allyloxycarbonyl(Alloc) and Propargyloxycarbonyl (Proc) Amino-Protecting Reagents

“…In this respect, and with attention to the growing interest in the development of polymer-supported reagents for organic synthesis, 11 our group has recently reported the facile preparation of an economical reagent which incorporates the N-hydroxysuccinimide moiety into a polymer. 12 This polymeric HOSu (P-HOSu, 9) has been employed as a solid supported racemization-lowering additive for DCCmediated peptide formation. 12 In addition, P-HOSu (9) has also been used for the preparation of reagents for the protection of amino groups with the 9-fluorenylmethoxycarbonyl (Fmoc) 13 or 2,7-di-tert-butyl-9-fluorenylmethoxycarbonyl (Dtb-Fmoc) 14 groups.…”

“…12 This polymeric HOSu (P-HOSu, 9) has been employed as a solid supported racemization-lowering additive for DCCmediated peptide formation. 12 In addition, P-HOSu (9) has also been used for the preparation of reagents for the protection of amino groups with the 9-fluorenylmethoxycarbonyl (Fmoc) 13 or 2,7-di-tert-butyl-9-fluorenylmethoxycarbonyl (Dtb-Fmoc) 14 groups. Furthermore, ammonium salts obtained from P-HOSu (9) have been employed as amino releasing and racemization-lowering reagents in carbodiimide-mediated amidations.…”

On the Synthesis and Selective Deprotection of Low-Generation Dendrons with Orthogonally Protected Peripheral Amine Groups and a Possible Impact of the Deprotection Conditions on the Stability of Dendronized Polymers' Skeletons

“…Thus, on the G2 level, the dendrons carry 4 Boc, 3 Boc and 1 Cbz, 2 Boc and 2 Cbz, 1 Boc and 3 Cbz, or, finally, 4 Cbz groups. At this point, it should be mentioned that another potentially promising pair of protecting groups, namely Boc and (9H-fluoren-9-ylmethoxy)carbonyl (Fmoc), could not be reasonably applied because the solubility of polymers which carry many Fmoc units is known to be very low [19]. It was, therefore, of utmost importance to check the degree of orthogonality of the chosen protecting groups.…”