438
A. K. Tipton and D. A. Lightner
(4Z)-14-tert-Butoxycarbonyl-10,17-dihydro-3,13-dimethyl-12-(2-ethoxycarbonyl)-2,7,8-
triethyl-tripyrrin-1(15H)-one (2; C31H43N3O5)
Dipyrrinone 3 (1.34 g, 5.0 mmol) was combined with ꢁ-acetoxymethylpyrrole 11 [18] (1.7 g,
5.0 mmol) in a solution of acetic acid (100 ml) and THF (53 ml). p-Toluenesulfonic acid
(80 mg, 0.5 mmol) was added in one portion and the solution was stirred at 40ꢀC for 3 h. The
solution was extracted with CH2Cl2 (3Â100 ml) and dried over anhyd. Na2SO4. After removal of
the solvent (rotovap) the remaining solid was ¯ash chromatographed with CH2Cl2/methanol
(97:3 (v/v)) to afford 2.2 g (75%) of a yellow solid which was crystallized from acetone/water to
give pure 2.
Yield: 1.62 g (60%); m.p.: 194±195ꢀC; IR (KBr): ꢊ 3348, 2965, 1740, 1630, 1458, 1365, 1250,
1168, 1074 cmꢂ1; UV/Vis "max 29800 (DMSO, 414 mm), 20000 (DMSO, 281 nm), 28000 (CHCl3,
406 nm), 20400 (CHCl3, 277 nm), 29500 (CH3OH, 414 nm), 20200 (CH3OH, 280 nm), 31500
1
((CH3)2CO, 404 nm), 31800 (C6H6, 412 nm); H NMR (CDCl3, ꢅ, 500 MHz): 0.983 (t, J 7.5 Hz,
3H, H-22), 1.08 (t, J 7.5 Hz, 3H, H-72), 1.18 (t, J 7.5 Hz, 3H, H-82), 1.46 (s, 9H, H-145, 146,
147), 2.14 (s, 3H, H-31), 2.26 (s, 3H, H-131), 2.29 (q, J 7.5 Hz, 2H, H-21), 2.45 (q, J 7.5 Hz, 2H,
H-71), 2.48 (t, J 7.5 Hz, 2H, H-121), 2.58 (q, J 7.5 Hz, 2H, H-81), 2.82 (t, J 7.5 Hz, 2H, H-
122), 3.68 (s, 3H, H-124), 4.01 (s, 2H, H-10), 6.13 (s, 1H, H-5), 9.22 (s, 1H, NH-23), 10.2 (s, 1H,
1
HN-22), 10.7 (s, 1H, NH-21) ppm; H NMR (DMSO-d6, ꢅ, 500 MHz): 0.805 (t, J 7.0 Hz, 3H, H-
22), 1.02 (t, J 7.5 Hz, 3H, H-72), 1.03 (t, J 7.5 Hz, 3H, H-82), 1.51 (s, 9H, H-145, 146, 147), 2.03
(t, J 8.0 Hz, 2H, H-121), 2.07 (s, 3H, H-31), 2.16 (s, 3H, H-131), 2.25 (q, J 7.0 Hz, 2H, H-21),
2.27 (q, J 7.8 Hz, 2H, H-71), 2.45 (q, J 7.0 Hz, 2H, H-72), 2.53 (t, J 8.0 Hz, 2H, H-122), 3.47
(s, 3H, H-124), 3.87 (s, 2H, H-10), 5.92 (s, 1H, H-5), 9.7 (s, 1H, NH-23), 10.23 (s, 1H, NH-21),
10.85 (s, 1H, NH-22) ppm; for 13C NMR data, see Table 1.
(4Z)-14-tert-Butoxycarbonyl-12-(2-carboxyethyl)-10,17-dihydro-3,13-dimethyl-2,7,8-
triethyl-tripyrrin-1(15H)-one (1; C30H41N3O5)
Tripyrrinone ester 2 (234 mg, 0.435 mmol) was combined with ascorbic acid (200 mg, 1.98 mmol)
and dissolved in THF (128 ml). Methanol (128 ml) and sodium hydroxide (0.2 M, 256 ml) were
added to the solution and stirred overnight under a nitrogen atmosphere. The solution was acidi®ed
with HCl (10%) until red on litmus paper. The tripyrrinone acid was extracted with CH2Cl2
(2Â100 ml), washed with sodium chloride (2Â100 ml), and dried over anhyd. Na2SO4. After removal
of the solvent (rotovap), the remaining solid was ¯ashed with dichloromethane/methanol (97:3 (v/v))
to afford 170 mg (75%) raw product. The yellow acid tripyrrole was crystallized from acetone to
afford pure 1.
Yield: 141 mg (64%); m.p.: 192±194ꢀC; IR (KBr); ꢊ 3421, 3268, 2964, 2931, 2870, 1251, 1170,
1102, 1057, 1007, 956, 871, 775, 690 cmꢂ1; UV/Vis: "max 20200 (DMSO, 415 nm), 21200 (DMSO,
282 nm), 29400 (CHCl3, 421 nm), 18300 (CHCl3, 279 nm), 33100 (CH3OH, 415 nm), 19700
(CH3OH, 282 nm), 30700 ((CH3)2CO, 420 nm), 32000 (C6H6, 427 nm); 1H NMR (CDCl3, ꢅ,
500 MHz): 1.07 (t, J 7.5 Hz, 3H, H-22), 1.18 (t, J 7.5 Hz, 3H, H-72), 1.22 (t, J 7.5 Hz, 3H, H-
82), 1.51 (s, 9H, H-145, 146, 147), 2.17 (s, 3H, H-31), 2.26 (s, 3H, H-131), 2.35 (q, J 8.0 Hz, 2H,
3
H-21), 2.55 (q, J 7.5 Hz, 2H, H-71), 2.56 (q, J 7.5 Hz, 2H, H-81), 2.75 (ddd, JBC 9.6 Hz,
3JCX 0.3 Hz, 3JAC 3.4 Hz, 1H, H-121), 2.78 (ddd, 3JBC 9.6 Hz, 3JBx 3.7 Hz, JAB 0.5 Hz, 1H,
2
3
3
H-122), 2.80 (ddd, JAX 3.4 Hz, JBX 3.7 Hz, JCX 0.3 Hz, 1H, H-121), 2.81 (ddd,
3
3
2JAX 3.4 Hz, JAB 0.5 Hz, JAC 3.4 Hz, 1H, H-122), 3.94 (s, 2H, H-10), 6.07 (s, 1H, H-5),
8.17 (s, 1H, NH-23), 9.02 (s, 1H, NH-22), 10.4 (s, 1H, NH-21), 13.48 (s, 1H, H-123) ppm; 1H NMR
(DMSO-d6, ꢅ, 500 MHz): 0.849 (t, J 7.0 Hz, 3H, H-22), 1.02 (t, J 7.5 Hz, 3H, H-72), 1.03
(t, J 7.0 Hz, 3H, H-82), 1.47 (s, 9H, H-145, 146, 147), 2.07 (t, J 7.3 Hz, 2H, H-121), 2.09 (s, 3H,
H-31), 2.12 (s, 3H, H-131), 2.26 (q, J 7.3 Hz, 2H, H-21), 2.27 (q, J 7.5 Hz, 2H, H-71), 2.45
(q, J 7.5 Hz, 2H, H-81), 2.53 (t, J 7.3 Hz, 2H, H-122), 3.87 (s, 2H, H-10), 5.93 (s, 1H, H-5), 9.70