Improved synthesis of trifluoromethyl substituted 3-spiro indolines and 3-indolyimines under microwaves irradiation

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:&quot;Calibri&quot;,&quot;sans-serif&quot;;mso-ascii-theme-font:minor-latin;mso-fareast-font-family: &quot;DejaVu Sans&quot;;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:Mangal; mso-bidi-theme-font:minor-bidi;color:#00000A;mso-ansi-language:EN-US; mso-fareast-language:EN-US;mso-bidi-language:AR-SA">The trifluoromethyl substituted 3' - phenyl spiro [3 H -indole-3-2' -thiazolidine]- 2,4' -(1H)-diones(VI) and 4,5-dihydro-3-phenyl spiro [2H-1,3-benzothiazine-2:3-[3H]-indole]-2',4 (1'H, 3H)-diones (VII) have been synthesized by the cyclo condensation of 3-indolylimines (III) with thioacids viz. Mercaptoacetic acid (IV a)/2-mercapto propionic acid (IV b) and <i style="mso-bidi-font-style:normal">O</i> mercapto benzoic acid (V), under microwave in open borosil glass vessels using either ethanol as energy transfer medium or silica gel as mineral solid support. The former compound, (III) have been synthesized by the condensation reaction of indole-2,3- diones (I)and trifluoromethyl substituted anilines (II) under microwave irradiation. The comparison of synthetic procedure under microwave and classical thermal method indicates tremendous reduction in time, higher selectivity, yield and purity compared to traditional methods. Characterization of the products has been done on the basis of elemental analyses; IR ¹<i style="mso-bidi-font-style:normal">H</i>NMR and ¹⁹<i>F</i>NMR spectral data Representative compounds have been 'Screened in vitro for antifungal activity against <i style="mso-bidi-font-style:normal">Rhizoctonia solani, Fusarium oxysporum and Colletotrichum capsici</i>.</span>