New Synthons For Formation of Heterocyclic Rings of Biological Interest

Hetercyclic Rings-Biological Interest.Areinally susbstiued sulphur- oxygen and sulpur compounds are important as natural products and target . Reactions Proceding by electrophiic to alkenes to give vicinal substitution of ox oxygen with a sulbhur are reviewed .sulphenyialion of unsalurated nitrles metal ions and varjous organic disulphides is reported .Thesynthetic and mechanistic aspects of these oxdative additions were discussed. the trifuoroacetoxy- sulpid thus prepared were trance formed into hydroxyl- sulphides by basic hydrolysis and to acetotamido- sulbid es by amodified Ritter reaction . Also ;the trifluoroacetoxy adducts ofhydrolys is give lactones whichare important as in natural roduct syntheses(butenolides ).Attemple to prpere lactams are discussed.The oxidative addition of disulphides to allylic and home aiiylic eslaers , and alsoallylic amides were studiedAmovel reqiochemical control is shown in the formation of ant Harkovnikov adduets from the trifluoraocetyl derivate –,in contrast wish the Markovnikov tye addition from the acetyl derivial to the neighbouring group part -. The stereochemistry of these additions is also Lxamples of trans formation of the adduets toskeletons of biolgocal desecribed.