Abstract
English AbstractConstruction of cyclohexane adducts via Diels-Alder reaction is an important issue in synthesis of natural products. This thesis describes an organic chemistry methodology development which is a novel process for the construction of highly congested cyclohexanes. The α-cyano-α,β- unsaturated ketones 19 and 22 can readily be prepared from the substituted acetonitriles 18 and ketones or aldehydes via a Knoevenagel condensation process. As we chose α-cyano-α,β-unsaturated ketone 19 as a dienophile, the Diels-Alder reaction with isoprene gave cyclohexane adduct 28, which obeyed the ortho-para rule respectively. When α-cyano-α,β-unsaturated ketone 22 acted as a dienophile, the Diels-Alder rection with 1,3-pentadiene gave stereoselective adducts 34 and 35. These cycloadducts was then treated with lithium naphthalenide followed by the addition of alkylating reagent methyl iodide or allyl bromide to give product 41, 42 and 47. Through this process, α-cyano-α,β-unsaturated ketones can be demonstrated to be a functional dienophile and act as equivalents of congested enones in Diels-Alder reaction. This process can also get stereoselective cyclohexanes through different functional groups on dienophiles. Thus, this newly developed process can expectably be utilized in structurally complex targets in organic synthesis.