LETTER
Facile Synthesis of 4-Diarylmethyl-1-(2H)phthalazinones
825
(11) Horn, H.; Morgenstern, E.; Unverferth, K. Pharmazie 1990,
45, 724.
(12) Klumpp, D. A.; Fredrick, S.; Lau, S.; Jin, K. K.; Bau, R.;
Surya Prakash, G. A.; Olah, G. A. J. Org. Chem. 1999, 64,
5152.
25 °C for 6 h and then poured over ice. The product was
extracted into CHCl3 and the organic phase was washed
twice with water, twice with brine, further washed with
water, dried over Na2SO4, and concentrated in vacuo. The
resulting solid was further purified by recrystallisation from
CHCl3 (yield ~70%).
(13) General Procedure for Preparation of 4a–4g, 5a–5c: The
appropriate substrate 1a–1g, 3a–3c (1.4 mmol) was added to
hydrazine hydrate (10mL, 99%) and the mixture refluxed for
about 15 minutes. The cooled reaction mixture was acidified
with 6 N HCl to pH 6. The solid product separated was
extracted with CHCl3 and worked up as usual. The residue
from the CHCl3 layer was purified by column chromato-
graphy over silica gel and CHCl3 eluate fractions afforded
pure solid products 4a–4g, 5a–5c which were crystallised
from CHCl3 –light-petroleum.
(14) 2,2 - Diaryl-1,3-indanediones 3a–3c were synthesized
following step-a and step-b (Scheme 1). Initially the mono-
arylated ninhydrin adducts, 2a–2c were synthesised by
stirring ninhydrin (1.4 mmol) and the appropriate hydro-
carbon Ar-H (4.2 mmol) in a mixture of acetic acid (10 mL)
and concd H2SO4 (1.0 mL) for about 0.5 h at room
temperature. The solid product separated was filtered out
and washed thoroughly with acetic acid and then with water.
The product was purified by silica-gel column chromato-
graphy using acetone as the eluent (yield ~85%).
(15) Spectral data for 4c: IR (KBr): (cm–1) 1659 (CO), 3170
(NH); 1H NMR ( ): 10.8 (1 H, s, NH), 8.46 (1 H, m, H-8),
7.73 (3 H, m, H-5, H-6, H-7), 7.28 (4 H, apparent d, J = 8.6
Hz, H-3 , H-3 , H-5 , H-5 ), 7.13 (4 H, apparent d, J = 8.6
Hz, H-2 , H-2 , H-6 , H- 6 ), 5.90 (1 H, s, H- ); 13C NMR
( ): 159.9 (C-1), 147.2 (C-4), 139.1 (C-1 , C-1 ), 133.6 (C-
6), 133.2 (C-4 , C-4 ), 131.5 (C-7), 130.6 (C-2 , C-2 , C-6 ,
C-6 ), 129.7 (C-9 or C-10), 128.9 (C-3 , C-3 , C- 5 , C-5 ),
128.5 (C-10 or C-9), 127.3 (C-8), 124.8 (C-5), 52.0 (C- ).
Anal. Calcd for C21H14Cl2N2O: C 66.15; H 3.70; Cl 18.60; N
7.35. Found: C 66.06; H 3.78; Cl 18.52; N 7.29%.
Spectral data for 4f: IR (KBr): (cm–1) 1667 (CO), 3176
(NH); 1H NMR ( ): 10.4 (1 H, br, NH), 8.45 (1 H, m, H-8),
7.79 (1 H, m, H-6), 7.71 (2 H, m, J = 8.6 Hz, H-5, H-7), 7.12
(4 H, apparent d, J = 8.7 Hz, H-2 , H-2 , H-6 , H-6 ), 6.84
(4 H, apparent d, J = 8.7 Hz, H-3 , H-3 , H-5 , H-5 ), 5.88
(1 H, s, H- ), 3.77 (6 H, s, 2 OCH3); 13C NMR ( ): 159.9
(C-1), 158.6 (C-4 , C-4 ), 148.6 (C-4), 133.4 (C-6), 133.3
(C-1 , C-1 ), 131.1 (C-7), 130.2 (C-2 , C-2 , C-6 , C-6 ),
130.1 (C-9 or C-10), 128.5 (C-10 or C-9), 127.1 (C-8), 125.2
(C-5), 114.1 (C-3 , C-3 , C-5 , C-5 ), 55.2 (2 OCH3), 51.7
(C- ). Anal. Calcd for C23H20N2O3: C 74.17; H 5.41; N 7.52.
Found: C 74.14; H 5.37; N 7.48%.
For the 2nd arylation of 2a–2c, the appropriate hydrocarbon
Ar -H (4.2 mmol) was added to a solution of monoarylated
ninhydrin 2a–2c (1.4 mmol) in a mixture of acetic acid (10
ml) and concd H2SO4 (3–4 mL). The mixture was stirred at
Synlett 2002, No. 5, 823–825 ISSN 0936-5214 © Thieme Stuttgart · New York