Electrophilic agents alteration

Minsavage, G.D., Dillman, J.F. (2007). Bifunctional alkylating agent-induced p53 and nonclassical nuclear factor kappaB responses and cell death are altered by caffeic acid phenethyl ester a potential role for antioxidant/electrophilic response-element signaling. J. Pharmacol. Exp. Ther. 321 202-12. 

Because of their electrophilic nature, Li" cations accelerate the reduction of carbonyl compounds by LiAlH4 or NaBH4. Li -complexing agents, such as cryptands, crown ethers or polyamines decrease the rate of reduction. In the case of a,p-unsaturated ketones, this slow down is associated with altered regioselectivity. For example, L1A1H4 reduction of cyclohexenones in the absence of the cryptand proceeds predominantly with 1,2-reduction. In the presence of the cryptand, 1,4-attack is favored. This selectivity is more pronounced with LiAlHa than with NaBHa (Scheme 36) and is also dependent on solvent. For example, with diethyl ether the 1,2-attack prevails, whereas when the cation is complexed, 1,4-addition predominates. 

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