Organic Reactions in Water and Other Alternative Media: Metal-Mediated Carbon-Carbon Bond Formations

Abstract

Metal-mediated carbonyl additions were investigated using several alternative media. Using the allylation as a model, metals were examined across the periodic table in mediating carbonyl additions in water. The effectiveness of metals as the mediator for the reaction was found closely related to the location of the metals in the periodic table and was tentatively rationalized via inner-sphere and outer-sphere single-electron -transfer processes. It was also found that, for allylation of aldehydes, water, liquid carbon dioxide, and neat conditions are all effective media when metals such as indium, tin and zinc were used as the mediators. Various homoallyl alcohols were prepared by these reactions. Under these conditions, allyl halides were found much more reactive than other types of organic halides. The cause for the special reactivity of allyl halides as well as the mechanism for forming allylmetal intermediates is discussed. 178

Theoretical Study of the Intrinsic Reactivities of Various Allylmetals toward Carbonyls and Water

“…In recent years, significant progress has been made in using water as a solvent for organic synthesis, especially for Barbier−Grignard allylation. In this connection, a number of metals, including beryllium, magnesium, manganese/copper, iron, zinc, cadmium, gallium, indium, , tin, , lead, antimony, and bismuth, , have been found to mediate the reaction of allyl halides with carbonyl compounds in aqueous media. Water is considered safe, inexpensive, and environmentally benign.…”