Bromoacetic acid

Disposable 5-mL polypropylene reactors fitted with a PTFE filter were acquired from Thermo Fisher Scientific (Hvidovre, Denmark). Tentagel S RAM resin, TFA, piperidine, and Fmoc-protected l- and d-amino acids were purchased from Iris-Biotech GmbH (Marktredwitz, Germany) Primary amines, bromoacetic acid, DIEA and Triisopropylamine were from Sigma-Aldrich (Søborg, Denmark). HOAt (1-Hydroxy-7-azabenzotriazole) and HATU (1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo [4,5-b]pyridinium 3-oxid hexafluorophosphate, N-[(Dimethylamino)-1H-1,2,3-triazolo-[4,5-b]pyridin-1-ylmethylene]-N-methylmethanaminium hexa-fluorophosphate N-oxide) were from GL Biochem (Shanghai, China). DMF (dimethylformamide, synthesis grade), DCM (dichloromethane, optical grade), MeCN (acetonitrile, optical grade) were from VWR (Copenhagen, Denmark). All reagents and solvents were used without further purification.

1-Decanol (98%) and 1-dodecanol (98%) were obtained from Merck KGaA (Darmstadt, Germany). Chloroacetic acid (99%), bromoacetic acid (97%), 1-bromododecane (97%), N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA) (99%), bis[2 -(N,N-dimethylamino)ethyl] ether (BDMAEE) (97%), D-glucose (99.5%) and Span 80 were obtained from Sigma-Aldrich (Poznan, Poland). Sulphuric acid and isopropanol (99%) were purchased from Chempur (Piekary Slaskie, Poland). Acetonitrile (≥99%), methanol (≥99%), calcium chloride (99%) and phosphorus pentoxide (98%) were obtained from VWR Chemicals (Gdansk, Poland). Barium sulfate (95%) and gelatin (95%) were purchased from WarChem (Warsaw, Poland). Sodium alginate from brown algae was obtained from Biomus (Lublin, Poland). Sunflower oil (food grade) was bought from Bunge Polska (Kruszwica, Poland).

The solvents and reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA), Acros Organics (Geel, Belgium), Alfa Aesar (Haverhill, MA, USA), or TCI (Tokyo, Japan) and used without further purification. Rink amide MBHA resin (typical loading level 0.52 mmol/g), DMF and NMP were purchased from Merck Millipore (Darmstadt, Germany). Bromoacetic acid, TIS, piperidine, CH₂Cl₂, benzylamine, (S)-(−)-1-phenylethylamine, Zn(OAc)₂, Cu(OAc)_2, pyridine, 4,4′-dipyridyl, 4,4′-trimethylene-dipyridine, ethylenediamine, 1,4-diaminobutane, 1,6-diaminohexane, piperidine, 4,4′-bipiperidine, 4,4′-trimethylenedipiperidine, cysteamine, 1,4-butanediol and Amberlyst A21 free base were purchased from Sigma Aldrich. DIC, l-Lys-OMe∙2HCl, d-Lys-OMe∙2HCl, and i-Pr₂NEt were purchased from TCI. Acetonitrile (ACN) and TFA were purchased from Acros Organics. Oasis^® 6cc Vac cartridge HLB (60 μm (LP), 6cc/500 mg) was purchased from Waters (Milford, MA, USA).

Per-O-acetylated GalNAz was prepared in four steps and 59% overall yield according to a protocol described by Laughlin and Bertozzi 34 (link). In short, bromoacetic acid (Sigma-Aldrich) was converted into azidoacetic acid N-succinimidyl ester and subsequently reacted with galactosamine hydrochloride (Carbosynth). The resulting GalNAz was peracetylated in the presence of acetic acid and pyridine, and purified by flash chromatography, eluting with 7:3 hexanes/ethyl acetate. GalNAz was resuspended in 100% ethanol for a 50 mM stock solution.

Triethylamine, triisopropylsilane
(TIS), 2-bromoethylamine
hydrobromide, Chloroform-d₁, sodium borohydride,
dimethyl sulfoxide-d₆, bromoacetic acid, N,N′-diisopropylcarbodiimide (DIC), 4-bromobenzyl
bromide, methanol-d₄, and H-Rink Amide
ChemMatrix were purchased from Sigma-Aldrich. Ditert-butyl dicarbonate and (benzotriazol-1-yloxy)tripyrrolidinophosphonium
hexafluorophosphate (PyBOP) were purchased from Novabiochem. Solvents
for peptide synthesis (analytical grade) were purchased from Sigma-Aldrich
(dimethylformamide) and J. T. Baker (diethyl ether). Trifluoroacetic
acid (TFA) and N,N-diisopropylethylamine
(DIEA) were purchased from Iris Biotech. Ethyl acetate and acetic
acid were purchased from J. T. Baker. Chloroform and dimethyl sulfoxide
were purchased from Chempur. Se powder and ethyl alcohol were purchased
from POCH. Amino acids were purchased from PeptideWeb. 4-Methoxybenzyl
chloride was purchased from TCI. Solvents for LC-MS and HPLC measurements
were as follows: acetonitrile (MeCN), formic acid (HCOOH), and water
were purchased from chemsolve and J. T. Baker. The solvent (HPLC grade)
for the irradiation experiments and UV–vis measurement was
methanol (MeOH), which was purchased from J. T. Baker. The solvent
for GC-MS measurement was dichloromethane (DCM), which was purchased
from Chemsolve.

Abbreviations for reagents are as follows: tert-butoxycarbonyl (Boc); 9-fluorenylmethoxylcarbonyl (Fmoc); trifluoroacetic acid (TFA); triisopropylsilyl (TIPS); N,N-dimethylformamide (DMF); N,N-diisopropylcarbodiimide (DIC); dimethylsulphoxide (DMSO). Solvents and reagents were purchased from commercial sources and used without further purification unless otherwise stated. Rink amide resin (typical loading level 0.6–0.8 mmol g^–1) was purchased from Merck4Biosciences. DMF was purchased from AGTC Bioproducts (National Diagnostics). Piperidine, bromoacetic acid and TFA were purchased from Sigma Aldrich. The amine building blocks were sourced from Sigma Aldrich or TCI Europe.