OXOKETENE DITHIOACETALS AS VERSATILE SYNTHONS FOR ALTERNATIVE 1,3 TO 1,11 CARBONYL TRANSPOSITIONS: A NEW POLYENE SYNTHESIS
A model strategy for 1,7 to 1,11 carbonyl transpositions involving 1,2 addition of sodium borohydride or Grignard reagents to polyenyl oxoketene dithioacetals 8 obtained by condensation of bis(methylthio)polyenals 1-3 with active methylene ketones, followed by borontrifluoride etherate catalyzed methanolysis of the resulting polyenyl carbinol acetals 9 to give 1,n transposed polyene esters 10 has been described.