Phenyl selenyl chloride, reaction with

The synthesis of enantiopure thiazolines has been reported. The mixture of enantiomerically pure diastereoisomeric amido selenides 64, obtained from the reaction of camphorselenyl sulfate with trans alkenes, when treated with Lawesson s reagent affords a mixture of two thioamide derivatives 65a and 65b. The two diastereoisomeric thioamide selenides were easily separated by chromatography, each was then treated with phenyl selenyl chloride which caused deselenylation to occur in a stereospecific manner furnishing the thiazolines 66a and 66b in an enantiopure form <02TA429>. 

Carbocyclic compounds can be formed by the nucleophilic intramolecular capture of a seleniranium intermediate of an olefinic bond. The carbonium ion which is formed as intermediate can react with another nucleophile or with the solvent. The first examples of these carbocyclization reactions were observed with dienes. Clive [105] reported that the reaction of the diene 203 with phenyl-selenyl chloride in acetic acid afforded the intermediate 204 which reacted with the solvent to give the bicyclic compound 205 (Scheme 31). Carbocyclization reactions were efficiently promoted by phenylselenyl iodide produced by diphenyl diselenide and iodine. As indicated in Scheme 31,Toshimitsu reported that the reaction of 1,5-hexadiene 206, in acetonitrile and water, afforded the acetamido cyclohexane derivative 209, derived from the cyclization of the seleniranium intermediate 207 followed by the reaction of the carbocation 208 with acetonitrile [106]. In several cases, carbocyclization reactions can be more conveniently effected by independently generating the seleniranium intermediates. A simple procedure consists of the reaction of trifluoromethane-sulfonic acid with j9-hydroxyselenides, which can be easily obtained from the... 

Stork and Raucher [76] have reported a chiral synthesis of PGA2 starting from 2,3-isopropylidene-L-erythrose from which they prepared the intermediate (85). Cyclisation with potassium t-butoxide in tetrahydrofuran and alkaline hydrolysis then afforded the keto acid (86a) which was transformed into PGA2 via reaction with lithium diisopropylamide and then phenyl selenyl chloride, oxidation of the product (86b) with sodium periodate and removal of the ethoxyethyl group. 

Phenyl selenocyanate is an important reagent for organic synthesis, capable of a wide variety of selenylation reactions. Until now the method of preparation has employed a diazo reaction however, in a new synthesis benzeneselenyl chloride reacts with trimethylsilyl cyanide to give phenyl selenocyanate in quantitative yield (Scheme 54). Since isolation simply involves evaporation of the solvent, this reaction represents a very simple synthesis of the useful reagent. 

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