New fields in organic chemistry: Developments in aqueous organoindium chemistry and ring closing olefin metathesis.

摘要

Organoindium chemistry is an area that has elicited considerable interest recently because it has been found that selected processes can be performed in aqueous media efficiently. These findings have caused a major impact in the quest for alternative synthetic pathways for pollution prevention. Similarly, the discovery of new reagents to perform ring closing metathesis reactions has received enormous attention in recent years. Grubbs' catalyst is the reagent that has revolutionized this area and provided the organic chemist with a powerful new synthetic tool. Novel methodologies in the areas of organoindium chemistry and ring closing olefin metathesis have been responsible for significant advances in synthetic chemistry in recent years.; Our goal was therefore to merge the fields of aqueous organoindium chemistry and ring-closing olefin metathesis (RCM) to develop methodologies with application in synthetic organic chemistry.; Initially, we examined the stereochemical course of the intramolecular cyclization of allylic bromides with indium metal in water. Proper comparison with the fluoride ion-promoted ring closure of allylsilanes in organic media was made.; The second stage of this work consisted in developing a general procedure for the synthesis of α-methylene lactones fused to larger rings. The convenient approach originates with two ω-unsaturated aldehydes of the same or different chain length. Organoindium chemistry and ring closing olefin metathesis were employed to develop the convergent strategy for the synthesis of α-methylene-γ-lactones fused to medium and large carbocyclic ring systems.; We also targeted for investigation a convenient method for achieving four-carbon intercalations between the carbonyl groups of α-diketones. A three-step sequence consisting of indium-promoted diallylation, ring-closing metathesis, and oxidative diol cleavage with lead tetraacetate lends itself conveniently to useful structural modifications.; Finally, we investigated the synthesis of an homologous series of bicyclo[1.1.1]pentane-1,3-dicarboxylate esters featuring ω-alkenols of differing chain length. Their ability to undergo ring closing metathesis/paddlane formation in the presence of Grubbs' catalyst was studied in detail.