LETTER
Lewis Acid Mediated Hydrolysis of Geminal Diesters
2097
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Acknowledgment
R.G. thanks CSIR-New Delhi, India for awarding a Senior Research
Fellowship. A.I. and M.P. are thankful to the Defence Research De-
velopment Organisation (DRDO), New Delhi for financial support
(ERIP/ER/0703613/M/01, dt. 23.05.2008). We thank DST-FIST
for use of the NMR and XRD facility at the School of Chemistry,
Bharathidasan University.
Supporting Information for this article is available online at
(24) Compound 6a and 8a both belong to a monoclinic system
with space group P21/n and P21, respectively.
m
iotSrat
ungIifoop
r
t
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre [CCDC-832627
(6a) and 832624 (8a)]. The crystal information file (CIF) can
be obtained free of charge from
References and Notes
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substituted aniline and amino acid methyl esters to obtain
novel amide derivatives such as (E)-ethyl 2-(2-
bromophenylcarbamoyl)-3-(phenylamino)acrylate and
found to show good antibacterial (e.g., E. coli) and
antifungal (e.g., C. albicans) activity.
(26) For details on racemization, isomerization and in situ NMR
studies see the Supporting Information.
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(29) General procedure for BF3·OEt2-mediated hydrolysis of
diethyl 2-[(aryl/alkyl-amino)methylene]malonate: To a
solution of diethyl 2-[(aryl/alkyl-amino)methylene]-
malonate (1.0 equiv) in chloroform (3 × w/v), BF3·OEt2 (1.0
equiv) was added and the mixture was stirred at r.t. under a
nitrogen atmosphere (the reaction was monitored by TLC).
Upon completion, the reaction mixture was quenched with
water (1 × w/v) and extracted with chloroform (3 × 5 mL).
The combined organic layer was dried (anhyd. Na2SO4) and
evaporated in a rotary evaporator. The crude product was
passed through a short column (silica gel) using a suitable
eluent to obtain the corresponding product in 40–92% yield.
Preparation of 2-(p-tolylaminomethylene)malonic acid
monoethyl ester (2b): The reaction was carried out
according to the general procedure using diethyl 2-(p-
tolylaminomethylene)malonate1 (1b; 500 mg, 1.8 mmol),
and BF3·OEt2 (453 μL, 1.8 mmol) in chloroform (1.5 mL) at
r.t. for 20 min. The title compound 2b (0.40 g, 90%) was
obtained as a white solid after passing through a short silica
gel column (hexane–EtOAc, 9:1). Mp 92 °C; 1H NMR (400
MHz, CDCl3): δ = 1.35 (t, J = 7.2 Hz, 3 H), 2.33 (s, 3 H),
4.32 (q, J = 7.2 Hz, 2 H), 7.06 (d, J = 8.4 Hz, 2 H), 7.18 (d,
J = 8.4 Hz, 2 H), 8.44 (d, J = 13.6 Hz, 1 H), 11.62 (d, J =
13.2 Hz, 1 H), 13.0 (br s, 1 H); 13C NMR (100 MHz,
CDCl3): δ = 14.3, 20.7, 61.3, 89.0, 177.7, 130.3, 135.9,
136.0, 151.6, 169.9, 170.7; IR (KBr): 3183, 2978, 2688,
1696, 1630, 1512, 1473, 1407, 1268, 1205, 1089, 1017, 887,
831, 811 cm–1; MS: m/z calcd. for C13H15NO4: 249.10;
found: 250.2 [M + 1]; Anal. Calcd for C13H15NO4: C, 62.64;
H, 6.07; N, 5.62. Found: C, 62.62; H, 6.08; N, 5.60.
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Synlett 2012, 23, 2093–2097