1,5-Asymmetric induction of chirality: diastereoselective addition of organoaluminium reagents and allylstannanes into aldehyde groups in the side-chain of π-allyltricarbonyliron lactone complexes
Abstract
π-Allyltricarbonyliron lactone complex 5, bearing an aldehyde group in the side-chain, can be easily prepared from commercially available (2E,4E
)-ethyl hexadienoate and reacts with organoaluminium and allylstannane nucleophiles to afford secondary alcohols. In analogy with the corresponding ketone-substituted complexes, the lactone tether acts via the Fe(CO)3 moiety as a source of asymmetric induction. The levels of diastereoselectivity are generally reduced, however, compared with those obtained using ketone complexes. This can be attributed, at least in part, to the carbonyl appendage adopting both s-cis and s-trans conformations. The level of 1,5-asymmetric induction is strongly dependent upon the nature of the nucleophile in the case of the organoaluminium reactions and upon the reaction temperature in the case of BF3-mediated addition of allylstannanes into the aldehyde group.
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