stereocontrol

p-Allyltricarbonyliron lactone complexes, h4-diene-tricarbonyliron complexes and their relatives offer an interesting approach to the problem of acyclic stereocontrol. Functional groups appended to the organic ligand fre-quently adopt a preferred conformation. This, combined with the steric bulk of the Fe(CO)3 moiety provides a means for controlling the addition of reagents to such pendant functionality in a defined manner. Thus addition of nucleo-philes to aldehydes and ketones affords a route to diaster-eoisomerically pure secondary and tertiary alcohols while olefinic functionality in the side-chain can be utilised in stereoselective dihydroxylations, Diels–Alder and Michael addition reactions. Just as the formation of arene Cr(CO)3 complexes modifies reactivity at the a-position of arene substituents, the Fe(CO)3 group of h4-diene and trimethyle