Iron-Mediated C-C Bond Formation. Preparation of (Trimethylenemethane)iron Complexes via Reaction of Weak Carbon Nucleophiles with in Situ Generated Cross-Conjugated Pentadienyl Cations. Nucleophilic Attack on (Trimethylenemethane)iron Complexes with Carbanions
American Chemical Society
Journal of Organic Chemistry
The reaction of (2-(acetoxymethylene)-1,3-butadiene)Fe(CO)(38 )o r ((acetoxymethy1ene)trimethylenemethane) Fe(C0)3 (9) with weak carbon nucleophiles in the presence of BFyEt20 gives the corresponding substituted (trimethylenemethane)Fe(C0)3 complexes as the major product. Applicable nucleophiles include trialkylaluminums, allyltrimethylsilane, and 2-((trimethylsilyl)oxy)- 1-propene. This reaction proceeds in a stereospecific fashion; reaction of 12 gives a single (trimethylenemethaneliron product. The reaction of (1,2-bis(acetoxymethylene)-1,3-butadiene)Fe-(Cola (20) with allyltrimethylsilane gives a (TMM)Fe(C0)3 product in which two new C-C bonds have been formed in one reaction. Reaction of TMMFe(C0)3 (la) and substituted derivatives with carbanions, followed by workup with trifluoroacetic acid, gives the corresponding methallylated product. Applicable nucleophiles include anions derived from diphenylmethane, ethyl isobutyrate, isobutylnitrile, and 2-phenyl-1,3-dithianee Use of allyl bromide in place of trifluoroacetic acid gives 6-substituted 5-methylene-1-hexenes as products, the result of a three-component coupling.