Asymmetric Pummerer rearrangement

G. Asymmetric Pummerer Rearrangement Induced by Ethoxy Vmyl Esters. . . 236... 

Asymmetric Pummerer rearrangement is a very attractive reaction as previously described. In particular, the reactions induced by SKA work well, and may be synthetically exploited in many cases. The results described here demonstrate that the stereoselective a-deprotonation of the sulfoxide is a prerequisite process for asymmetric induction in the Pummerer reaction. Since many kinds of synthetic and enzymatic preparative methods of optically pure sulfoxides have been developed, the present Pummerer-type reaction will be applicable to many other chiral sulfoxides with one a-substituent, chiral vinylsulfoxides and chiral co-carbamoylsulfox-ides, thus leading to enantioselective syntheses of many new bioactive compounds in the near future. 

Kita et al. have reported an asymmetric Pummerer rearrangement of optically active sulphoxides, induced by ethoxy vinyl esters (EVE). In particular ethoxy vinyl acetate 50 was used to effect the Pummerer rearrangement of sulfoxides 51a-b in good yields and high enantioselectivity. 

---