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P. P. Seth et al. / Tetrahedron Letters 43 (2002) 7303–7306
in place of 10% Pd/C for nitro group reduction. Method
183.4, 162.9, 147.1, 143.0, 140.8, 138.6, 138.4, 137.5,
136.5, 128.9, 124.5, 120.0, 113.5, 38.1. HRMS calcd for
C16H12N4O: 277.1084, observed: 277.1085. 5b: H NMR
C: This method was identical to Method A, except that
1h (1 mmol) was heated with MeNH2 (2 mL) in a sealed
tube at 100°C and sequentially treated with BzNCS (1.1
equiv.), PS-Trisamine (25 mg) followed by ring closure
with EDC (1.5 mmol) and DIPEA (5 mmol).
1
(400 MHz, DMSO-d6): l 12.9 (s, br, 1H), 8.25 (d, 2H,
J=6.8), 8.1 (s, 1H), 7.87 (d, 1H, J=6.8), 7.55–7.45 (m,
5H), 3.85 (s, 3H), 3.71 (s, 3H). 13C NMR (100 MHz,
DMSO-d3): l 183.2, 175.7, 162.9, 147.3, 143.2, 140.7,
138.3, 137.5, 136.4, 133.6, 133.1, 122.2, 118.8, 61.6, 38.0.
HRMS calcd for C17H15N3O3: 310.1186, observed:
310.1190. 5c: 1H NMR (400 MHz, CDCl3): l 12.59 (s, br,
1H), 8.36 (d, 2H, J=6.8), 7.55–7.44 (m, 5H), 7.31 (d, 1H,
J=7.6), 3.80 (s, 3H). 13C NMR (100 MHz, CDCl3): l
181.2, 159.2, 141.7, 136.9, 135.9, 133.5, 132.5, 132.3,
129.8, 127.1, 124.7, 113.2, 112.7, 32.8. HRMS calcd for
C16H12F3N3O: 320.1005, observed: 320.1013. 5d: 1H
NMR (400 MHz, DMSO-d6): l 12.79 (s, br, 1H), 8.24 (d,
2H, J=6.8), 7.66 (s, 1H), 7.52–7.38 (m, 5H), 3.68 (s, 3H).
13C NMR (100 MHz, DMSO-d6): l 183.1, 162.2, 147.4,
140.7, 139.7, 138.9, 138.2, 137.4, 136.8, 134.6, 123.7,
120.8, 37.9. HRMS calcd for C15H12BrN3O: 330.0236;
12. Piperidine (33 mL, 0.34 mmol) was added to a solution of
13e (30 mg, 0.068 mmol) in DMF (0.3 mL). The reaction
was stirred at rt for 14 h after which it was loaded onto
a short plug of silica gel. The plug was eluted with 50%
EtOAc/hexanes followed by 10%MeOH/1%NH4OH/
CH2Cl2. The CH2Cl2 fractions were collected, concen-
trated and the resulting solid was redissolved in CH2Cl2
(0.5 mL) and DIPEA (50 mL). The reaction was cooled in
an ice bath and PhCH2COCl (0.08 mmol, 11 mL) was
added. The reaction was stirred for 14 h at rt after which
it was diluted with CH2Cl2 and the organic layer was
washed with dil. HCl, brine, dried (MgSO4) and concen-
trated to yield 14e (85% over two steps).
13. Other methods for deprotection of the Fmoc group in 13e
were also examined. We found that the Fmoc group
could be successfully deprotected using PS-trisamine
resin. Unfortunately we were never able to completely
scavenge the dibenzofulvene from the reaction using PS-
trisamine resin under a variety of conditions. We also
attempted to replace the FmocNCS with CbzNCS to
allow for cleaner deprotection. However, CbzNCS is not
commercially available and its synthesis was complicated
due to the formation of side products.
1
observed: 330.0236. 5e: H NMR (400 MHz, CDCl3): l
12.41 (s, br, 1H), 8.32 (d, 2H, J=6.8), 7.51–7.26 (m, 6H),
3.72 (s, 3H). 13C NMR (100 MHz, CDCl3): l 176.8,
154.6, 137.3, 131.6, 129.8, 129.2, 128.0, 127.9, 127.1,
126.9, 112.5, 110.4, 28.5. HRMS calcd for C15H11Cl2N3O:
1
320.0352, observed: 320.0343. 11m: H NMR (400 MHz,
CDCl3): l 12.42 (s. br, 1H), 8.31 (d, 2H, J=6.8), 7.55–
7.31 (m, 5H), 4.01 (d, 2H, J=7.6), 2.37 (m, 1H), 1.035 (d,
6H, J=6.8). 13C NMR (100 MHz, CDCl3): l 176.9,
154.9, 137.5, 131.6, 129.6, 129.2, 128.0, 27.7, 126.9, 126.7,
112.4, 110.9, 60.5, 49.9, 28.1, 20.3. HRMS calcd for
C18H17Cl2N3O: 362.0821, observed: 362.0827.
14. Analytical data for some 2-(N-benzoyll)-aminobenzimi-
1
dazoles. 5a: H NMR (400 MHz, DMSO-d3): l 12.93 (s,
br, 1H), 8.25 (d, 2H, J=6.8), 7.79 (s, 1H), 7.67–7.46 (m,
5H), 3.71 (s, 3H). 13C NMR (100 MHz, DMSO-d3): l