The natural extracts were being collected, dried above Na2SO4 and evaporated under vacuum

The crude was purified by flash chromatography eluting with CHCl3/MeOH (9:one) to afford to pay for 36 (one.32 g, seventy six%). To a answer of 33 (.five g, 2.46 mmol), 34 (.eighty two g, two.46 mmol), 35 (.fifty seven g, two.46 mmol), and 36 (one.seventeen g, two.46 mmol) in CH2Cl2 (15 mL) N-hydroxysuccinimide (NHS) (.28 g, two.46 mmol) was additional. When important, a little total of THF (ca. 4 mL) was extra to improve solubility. 1st, intermediates 19?one ended up obtained by reacting one,4naphthoquinone (22) (.67 g, four.23 mmol) with tert-butyl 4aminophenylcarbamate (23) (.88 g, 4.23 mmol), tert-butyl 4aminobenzylcarbamate (24) (.94 g, 4.23 mmol), 439574-61-5and tert-butyl 4(aminomethyl)benzylcarbamate (twenty five) (1 g, 4.23 mmol), respectively, in methanol (15 mL) at space temperature for four h. Soon after precipitation, compounds 19 (.90 g, 58%), twenty (.87 g, 54%), and 21 (.72 g, forty eight%) had been gathered by filtration and applied in the upcoming move devoid of any even more purification. Compounds 19 (.sixty seven g, one.83 mmol), twenty (.sixty nine g, 1.eighty three mmol), and 21 (.seventy two g, one.83 mmol) were being dissolved in dry CH2Cl2 (15 mL) and trifluoroacetic acid (TFA) (2.8 mL, 36.six mmol) was added dropwise at 0uC. After stirring for five h at room temperature, the solvent was evaporated below vacuum, washing with heptane (three periods) to take away the surplus of TFA. The crude extracts had been then dissolved in drinking water and washed with ether (3620 mL). The drinking water was made simple with Na2CO3 and extracted with CH2Cl2 (3630 mL). The organic extracts ended up gathered, dried and evaporated below vacuum to afford to pay for compounds sixteen (.forty four g, 92%), 17 (.forty eight g, 94%), by a catalytic sum of four-dimethylaminopyridine (DMAP) (4 mg). The reactions ended up stirred under nitrogen at room temperature overnight. The shaped white reliable was removed by filtration and the filtrates ended up evaporated to dryness. The resulting residue was taken up with ethyl acetate (thirty mL) and extracted with 10% NaHCO3 (3620 mL). The natural levels were being dried in excess of Na2SO4 and concentrated in vacuo to pay for the guarded and activated amino acids 27 (.63 g, 85%), 28 (.64 g, 60%), 29 (.seventy four g, 92%) and thirty (.62 g, forty four%). For characterization data of 34 and 27?, see File S1. Synthesis of quinone-amino acid conjugates 1. Reagents and Circumstances: a) MeOH, rt, 4 h b) TFA, DCM, rt, five h c) dioxane, DMAP, reflux, 24 h for 1 CH2Cl2, rt five h for 6?5 d) TFA, CH2Cl2, rt. The final coupling was carried out making use of a Carousel 12 Plus reaction station. The secured and activated amino acids 26 (.067 g, .15 mmol), 27 (.045 g, .15 mmol), 28 (.064 g, .15 mmol), 29 (.049 g, .fifteen mmol) and 30 (.085 g, .fifteen mmol) were being dissolved in dry CH2Cl2 (4 mL). Compounds seventeen (.042 g,.15 mmol) and eighteen (.044 g, .15 mmol) have been then additional and the resulting solutions have been stirred for 5 h at home temperature.