Download (4Mb) - Etheses - Saurashtra University

Part – B Studies on isatin derivatives…..
later compounds have been previously prepared using dihaloalkanes and
NaH in dioxane 134 or DMF 188 or by the use of LiH. 189 Some of these
alkylation methodologies were evaluated for the synthesis of isatins bearing a
glycosidic residue linked to the N-1 position. 190 Use of KF and Al2O3 with
acetonitrile 191 and THF 191 is also reported for N-alkylation of isatin. Literature
also revealed uses of different bases viz. pyridine in benzene, 192
diisopropylethylamine in dichloromethane, 176 cuprous oxide in DMF, 193
BEMP (2-tert-butylimino-2-diethylamino-1, 3-dimethylperhydro-1, 3, 2diazaphosphorine
on polystyrene) in acetonitrile 194 and potassium t-butoxide
in THF. 195
An alternative method for preparing 1-alkylisatins consists in the
reaction of isatin and alkyl halides in a benzene-chloroform/50% aq. KOH
biphasic system, employing tetrabutylammonium hydrogensulfate as the
phase transfer catalyst. 196
184, 197
N-propargylisatins, obtained from isatin and propargyl halides
can be converted to N-acetonylisatins through hydration with Hg(II) salts in
acidic media. 198
The synthesis of 1-methylisatin by the method of Stolle, using tris
(methylphenylamino) methane instead of N-methylaniline, leads to the desired
product in low yields. 199
The reaction of isatin with vinyl acetate in the presence of Na2PdCl4
yields 1-vinylisatin. 200
On the other hand, O-alkylation at position 2 has been reported, along
with the N-alkyl product, using γ- butyrolactone 201 or allyl bromide 202 as
alkylating agents and the sodium salt of isatin. O-methylisatin is described as
the product of the reaction of methyl iodide with the silver salt of isatin, which
can be prepared from isatin and silver acetate. 203 The alkoxy group has been
reported to be displaced by nucleophiles such as hydrazines. 204
Department of Chemistry, Saurashtra University, Rajkot-360 005 117