Skeletal Rearrangements of Unsaturated Sulphides

Important variants of procedure have been tested, providing wider possibilities for thio-Claisen rearrangements in synthesis like any other method for forming carbon-carbon bonds whose scope exceeds its limitations, there is the likelihood of studies of the type described in this Section being taken up in many more laboratories. Lithiation of allyl sulphides is followed by rearrangement, providing a very efficient method for the synthesis of thiols, alkyl sulphides, and hydrocarbons of the squalene type, or based upon the artemisyl skeleton. Typically, benzyl yy-dimethylallyl sulphide (65) gives (66) with four equivalents of 

Bu Li at - 30 °C, followed by treatment with Mel. A diallyl sulphide behaves similarly in that one of the two S-substituents is lithiated, and this centre is the point at which the y-carbon of the other S-substituent is attached in the product. Compounds (67)—(69) are formed in approximately equal amounts by the photolysis of the /S-alkylthioalkyl-carbene derived from 3-crotyl-3-methylbutyrophenone tosylhydrazone sodium salt. An a-allylthioalkyl-carbene (70) behaves differently on irradiation at - 70 °C, giving an intermediate (71) which rearranges, without the need for irradiation, to give the violet thione (72) this last step is the first 

Tanaka, T. Katagiri, K. Tanabe, and S. Takeshita, Yuki Gosei Kagaku Kyokai Shi, 

New dithio-ester and thioamide syntheses are reported, based upon the reaction of chloropropiolonitrile C1C=C-CN with two equivalents of allenethiol in the presence of NaOMe, to give (74), and of )ViV-diethyl-aminopropiolonitrile with allenethiol in the presence of NaOMe, to give (75).  

---