IRON-MEDIATED C-C BOND FORMATION - PREPARATION OF (TRIMETHYLENEMETHANE)IRON COMPLEXES VIA REACTION OF WEAK CARBON NUCLEOPHILES WITH IN-SITUGENERATED CROSS-CONJUGATED PENTADIENYL CATIONS - NUCLEOPHILIC-ATTACK ON (TRIMETHYLENEMETHANE)IRON COMPLEXES WITH CARBANIONS

The reaction of (2-(acetoxymethylene)-1,3-butadiene)Fe(CO)(3) (8) or ( (acetoxymethylene)trimethylenemethane)Fe(CO)(3) (9) with weak carbon n ucleophiles in the presence of BF3 . Et(2)O gives the corresponding su bstituted (trimethylenemethane)Fe(CO)(3) complexes as the major produc t. Applicable nucleophiles include trialkylaluminums, allyltrimethylsi lane, and 2-((trimethylsilyl)oxy)-1-propene. This reaction proceeds in a stereospecific fashion; reaction of 12 gives a single (trimethylene methane)iron product. The reaction of 1,2-bis(acetoxymethylene)-1,3-bu tadiene)Fe-(CO)(3) (20) with allyltrimethylsilane gives a (TMM)Fe(CO)( 3) product in which two new C-C bonds have been formed in one reaction . Reaction of TMMFe(CO)(3) (1a) and substituted derivatives with carba nions, followed by workup with trifluoroacetic acid, gives the corresp onding methallylated product. Applicable nucleophiles include anions d erived from diphenylmethane, ethyl isobutyrate, isobutylnitrile, and 2 -phenyl-1,3-dithiane. Use of allyl bromide in place of trifluoroacetic acid gives 6-substituted 5-methylene-1-hexenes as products, the resul t of a three-component coupling.