Iron chlorides decomplexation

The iron complex 16 in anhyd benzene was treated with an alkyl halide (excess) and anhyd NaHC03 (1 mol equiv) and the mixture was stirred at 20 "C for 20 h. For acylation, an acyl chloride (1 mol equiv) and anhyd NaHCO, were employed and the mixture was stirred at 20CC for 1-2 h. For decomplexation, the TV-substituted iron complex 17 and a 20-fold molar excess of freshly sublimed Me3NO in acetone were stirred for 20 h at 20 C and the reaction mixture was worked up by chromatography to give 18. 

Decomplexation of the carbomethoxylated compounds 145.g, 145.C, and 145.b could also be carried out using an excess of methanolic iron(III) chloride, which at lower temperatures yielded the expected diesters (160)... 

Reaction of tricarbonyl(cycloheptatriene)iron 13 with dichlorocarbene resulted in cyclopropanation of the uncomplexed double bond giving cyclopropane 14. Decomplexation failed with trimethylamine oxide, but was successful with copper(II) chloride. 

Another early solution to the acetate aldol problem came from the so-called Davies-Liebeskind enolates already mentioned in the context of enolate alkylation. As elaborated independently by the groups of Davies [138] and Liebeskind [139], the deprotonation of the chiral acetyl iron complex 124b, transmetallation of the lithium enolate, and addition to aldehydes lead to the predominant formation of diastereomers 279, as proved by a crystal structure analysis. The diastereoselectivity strongly depends on the transmetallation, the best results being obtained with diethylaluminum chloride. With other additives, the topicity is reversed, and the diastereomer 280 is obtained as the major product. The decomplexation of the adducts leads to P-hydroxycarboxylic acids (Scheme 4.64). 

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