6, 7, 8, 9 and 10 Although invasive fungal diseases are now more frequent than during the first half of the century, they are still difficult to diagnose clinically. During the latter half of the century, particularly during the past Fulvestrant solubility dmso two decades, a number of different classes of antifungal agents have been discovered. 11, 12 and 13 Despite advances in antifungal therapies, many problems remain

to be solved for most antifungal drugs available. Clotrimazole 14 and 15 was used as the standard drug for the present study. The use of azoles, such as fluconazole, ketoconazole and miconazole, has resulted in clinically resistant strains of Candida spp. 16 and 17 A 3.6–7.2% of vaginal isolates of Candida albicans from women with Candidal vaginitis is resistant to fluconazole. 18 This situation highlights the need for advent of safe, novel and effective antifungal compounds. Recently, some new,

imidazo [2, 1-b]-benzothiazole and their derivatives have been synthesized as antibacterial, diuretic, Smoothened inhibitor antifungal and anti-HIV agents. Imidazole [2,1,b], thiazole, 19 imidazo [2, 1-b]-benzothiazole 20 and 21 and their bio-isosteric derivatives are also regarded as safer and better drug molecules. 22 In view of the previous study and in continuation of an ongoing program aiming at finding new structure leads with potential antifungal activity, Thalidomide new series

of substituted diaryl Imidazole [2, 1-b]-benzothiazole derivatives have been synthesized and screened for antifungal activity. The 2-amino-6, 7-disubstituted benzothiazoles (3a–h) were synthesized by the reaction of substituted aniline (1a–h) and potassium thiocyanate in the presence of glacial acetic acid at 0 °C by following the literature procedure.23 The synthesis of 1, 2-(4-substituted) diaryl-1-ethanones (6a–i) was carried out by reacting appropriate phenylacetic acid (4a–c) with various substituted aromatic hydrocarbons in the presence of orthophosphoric acid and trifluoroacetic anhydride (5a–c). The resulting intermediates (6a–i) were subjected to bromination using liquid bromine in chloroform to obtain α-bromo-1,2-(4-substituted) diaryl-1-ethanones (7a–i) as show in Scheme 1. 19 The synthesis of substituted diaryl imidazo [2, 1-b]-benzothiazoles (8a–y) was carried out by condensation of 2-amino benzothiazole (3a–h) with substituted α-bromo-1, 2-(p-substituted) diaryl-1-ethanones (7a–i) in suitable solvent. This method provides required substituents at 2-, 5- and 6- position by starting with appropriately substituted synthons. The resulting free bases are obtained by neutralization of the salts with sodium carbonate solution.