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1070851 
Journal Article 
Regio- and Stereoselectivity in the Reactions of Organometallic Reagents with an Electron-Deficient and an Electron-Rich Vinyloxirane: Applications for Sequential Bis-Allylic Substitution Reactions in the Generation of Vicinal Stereogenic Centers 
Dieter, RK; Huang, Y; Guo, F 
In Press 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
English 
Vinyloxiranes provide opportunities for bis-allylic substitution reactions and the generation of new vicinal stereogenic centers if regio- and stereocontrol can be achieved. Ethyl (E)-4,5-epoxy-2-hexenoate affords excellent S(N)2':S(N)2 regioselectivity and anti:syn product diastereoselectivity with dialkyzinc reagents in the presence of CuCN, and conversion of the resultant allylic alcohol to the acetate affords good syn:anti product diastereoselectivity in S(N)2'-selective allylic substitutions with alkylcyanocuprates in THF. (E)-1-(tert-Butyldimethylsilyloxy)-2,3-epoxy-4-hexenonate gives excellent S(N)2':S(N)2 regioselectivity and anti:syn product diastereoselectivity with dialkyzinc reagents in THF or DMF or Grignard reagents in Et(2)O/THF (10/1) in the presence of CuCN. Conversion of the product allylic alcohol into the allylic phosphate affords excellent S(N)2' regioselectivity and syn:anti product diastereoselectivity with lithium alkylcyanocuprates for primary and secondary alkyl transferable ligands, while S(N)2 regioselectivity is observed for the tert-butyl ligand. Reaction conditions have been developed for regio- and stereocontrolled bis-allylic substitution reactions on both electron-rich and electron-deficient alkenyloxiranes, providing a methodology for the generation of vicinal alkane stereogenic centers. 
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