تفاعل #79472

معادلة التفاعل

tosylate

N-tert-Butoxycarbonyl-trans-4-(p-toluenesulfonyloxy)-D-proline diphenylmethyl ester

N4-benzoylcytosine

K2CO3

18-crown-6

→

N-tert-butoxycarbonyl-cis-4-(N4-benzoylcytosin-1-yl)-D-proline diphenylmethyl ester

N-tert-Butoxycarbonyl-cis-4-(N4-benzoylcytosin-1-yl)-D-proline diphenylmethyl ester

المذيبات

dichloromethane

DMF

ظروف التفاعل

المعالجة

1. 1
   ترشيحfiltered through celite
2. 2
   غسيلthe organic phase washed with water
3. 3
   أخرىEvaporation
4. 4
   أخرىgave the crude product as an oil which
5. 5
   أخرىwas purified by column chromatography (SiO2, ethyl acetate)
6. 6
   أخرىevaporated
7. 7
   أخرىto give the N1-isomer (0.299 g, 25%) as a white foam
8. 8
   أخرىRecrystallisation from ethanol-water

الإجراء التجريبي

A reaction mixture containing the trans-D tosylate (7) (1.10 g, 2.00 mmol), N4-benzoylcytosine (0.475 g, 2.20 mmol), anhydrous K2CO3 (0.300 g, 2.20mmol) and 18-crown-6 (200 mg) in DMF (10 ml) was stirred at 70-80° C. under argon overnight. The white suspension was diluted with dichloromethane (75 ml), filtered through celite and the organic phase washed with water. Evaporation gave the crude product as an oil which was purified by column chromatography (SiO2, ethyl acetate). The more polar fractions (Rf 0.33) were combined and evaporated to give the N1-isomer (0.299 g, 25%) as a white foam. Recrystallisation from ethanol-water gave white crystals of N-tert-butoxycarbonyl-cis-4-(N4-benzoylcytosin-1-yl)-D-proline diphenylmethyl ester (11), m.p. 133-135° C., (Found C, 65.8; H, 6.5; N, 8.8%; C34H34N4O6.C2H5OH.H2O requires C, 65.6; H, 6.4; N, 8.5%), δH (200 MHz; CDCl3) 1.30 and 1.49 (9H, 2×s, Boc rotamers), 2.20 and 2.90 [2H, br m, CH2(3′)], 3.50-3.80 and 3.95-4.15 [2H, 2×br m, CH2(5′)], 4.45-4.70 [1H, br m, CH(2′)], 5.28 [1H, br m, CH(4′)], 6.87 (1H, s, CHPh2), 7.15-7.40 (10H, m, phenyl CH), 7.40-7.75 [5H, m, CH(5), CH(6) and benzoyl m- and p-CH], 7.89 (2H, d, J=7.4 Hz, benzoyl o-CH), 8.83 (1H, br s, NH); δC (50.28 MHz; CDCl3) 27.7 and 28.0 (Boc CH3 rotamers), 34.4 and 36.0 [CH2(3′) rotamers], 49.6 and 50.5 [CH2(5′) rotamers], 54.3 and 54.9 [CH(4′) rotamers], 57.6 [CH(2′)], 78.0 and 78.3 (CHPh2 rotamers), 81.3 (Boc C), 96.8 [CH(5)], 127.0-129.2 (aromatic CH), 133.4 (benzoyl C), 139.5 (aromatic C), 145.2 and 145.7 [CH(6) rotamers], 153.8 (Boc CO rotamers), 155.6 [C(2)], 162.0 [C(4)], 166.8 (benzoyl CO), 171.3 (ester CO); m/z (ES MS) 595 (M+H+, 100%); νmax (KBr)/cm−1 1743 (C═O), 1704s (C═O); λmax (CHCl3)/nm 266 (ε/dm3.mol−1.cm−1 8.9×104), 312 (3.4×104); [α]D23−13.6 (c=0.50, CHCl3).

المصدر