Sulfur ylides. 11. Selected chemical transformations of 1-methylthio-3,4-dihydropyrido[2,1-a]isoindole-2,6-dione

The reaction of 1-methylthio-3,4-dihydropyrido[2,1-a]isoindole-2,6-dione (2) with NaBH4led to reduction of the keto group to the hydroxy group. The reaction with the use of LiAlH4resulted in complete reduction of the carboximide group, reduction of the keto group to the hydroxy function, and reduction of the double bond accompanied by desulfurization. The reaction of indolizidinedione 2with Zn afforded a reductive desulfurization product. The reactions of 2with hydrazine hydrate, hydroxylamine, and formamide proceeded according to a mechanism typical of the keto group to give hydrazone, oxime, and the formyl derivative, respectively. Oxidation of the thiomethyl group of the starting compound with ButOOH gave rise to sulfone or sulfoxide depending on the amount of the oxidizing agent used.