Chemistry of Substituted (2-Butene-1,4-diyl)magnesium: A Facile Approach to Complex Carbocycles, Functionalized Ketones and Alcohols, and Silicon-Containing Heterocycles

Article abstract of DOI:10.1021/jo00009a034

Highly reactive magnesium reacts with a wide variety of substituted 1,3-dienes to give the corresponding substituted (2-butene-1,4-diyl)magnesium complexes.Reactions of symmetrical (2-butene-1,4-diyl)magnesium with α,ω-alkylene dihalides form three-, four-, five-, and six-membered carbocycles.Significantly, the cyclizations are always stereospecific and completely regioselective.Depending on the initial 1,3-diene and specific electrophiles, uncyclized products can be obtained.Stepwise reactions of (2,3-dimethyl-2-butene-1,4-diyl)magnesium with two different electrophiles afford polyfunctionalized ketones with the generation of a quaternary center.Formal 1,2-additions can be effected in this manner.Substituted five- and six-membered cyclic ketones can also be synthesized in one step by this approach.Treatment of unsymmetrical (2-butene-1,4-diyl)magnesium complexes with triorganosilyl chlorides followed by cyclohexanone results in additions across a terminal double bond with high regioselectivity.Silicon-containing heterocycles or spiro compounds can be readily synthesized by using the bis-Grignard reagents.