Synthesis and derivatization of angular 3-chloro-3-chlorosulfenyl naphtho[1,2-b]pyran(4H)-4-ones with evaluation of antiviral activity

Abstract

Angular 2,3-dihydronaphtho[1,2-b]pyran(4H)-4-ones 1a,b react with an excess of thionyl chloride to give the α-chlorosulfenyl chlorides 2a,b, which are reduced by iodide ion to give the corresponding 1,3,4-oxadithiino derivatives 3a,b. However, the aducts 4a,b and 5a,b were obtained by reduced 2a,b with iodide ion in the presence of 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene, respectively. Direct oxidation of 2a,b afford 3,3-dichloronaphthopyran-4-ones 6a,b, whilst conversion to the sulfenamides 7a,b prior to oxidation provides 3-chloronaphthopyranones 8a,b. While α-chloro β-oxo sulfenyl chlorides 2a,b undergo straight forward substitution with 1-methylpiperazine and with potassium cyanide to give 9a,b and 10a,b, respectively. Some of the prepared products were selected and tested for their antiviral activity against herpes simplex virus type-1 (HSV-1). Plaque reduction infectivity assay was used to determine virus count reduction as a result of treatment with test compounds. Compound 5a showed moderate effect against HSV-1.