NEW DEVELOPMENTS OF THIOCARBONYL COMPOUNDS AND SULFINES IN ORGANIC-SYNTHESIS

The oxidation reaction of aliphatic thiocarbonyl compounds has been re visited in order to give access to the elusive corresponding sulfines and to achieve thiophilic addition of nucleophiles. Various compounds (thioketones, dithioesters, thionesters, trithiocarbonates, trithioper esters) have been treated with a peroxycarboxylic acid. In all cases t he corresponding sulfines are formed, in contrast to literature expect ations. Their behaviour towards nucleophiles has been investigated. Th e reaction with alkylithiums proved very useful: a clean and rapid thi ophilic addition (no enethiolization) was observed at -78 degrees C. T he resulting dithioacetal monoxides are easily transformed into carbon yl compounds (aldehydes, ketones) either by a simple mineral acid trea tment or by a spontaneous rearrangement which takes place at ambient t emperature. It provides a new formal entry to acyl anions (formed by a n addition reaction and not by deprotonation). A second illustration o f the specific properties of sulfur compounds is disclosed with a new asymmetric version of the Claisen rearrangement. Sulfur is used to fac ilitate the thermal course of the reaction and a sulfinyl adjacent gro up is introduced for diastereocontrol First examples show that this tr ansposition indeed occurs at room temperature and with an excellent di astereomeric ratio (greater than or equal to 93.7).