Benzoin-Type Reactions and Tandem C-C Bond Forming Reactions Using Acyl Anion Equivalents Public Deposited

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  • March 20, 2019
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  • Bausch, Cory Charles
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • I. Cross Silyl Benzoin Additions Catalyzed by Lanthanum Tricyanide. From a screen of (cyanide)metal complexes, an improved catalyst for the cross silyl benzoin addition was discovered. Several M(CN)3 complexes (M equals Ce, Er, Sm, Y, Yb, La) were evaluated and lanthanum tricyanide was identified as the optimal catalyst. The catalyst, prepared in situ from LaCl3, effects the selective coupling of aryl and alkyl acylsilanes with aryl, heteroaryl, α,β-unsaturated, and aliphatic aldehydes. The reactions occur at ambient temperature in less than five minutes to provide, depending on the workup, α-hydroxy or α-silyloxy ketones in 48-93% isolated yield. II. Cyanide-Catalyzed Additions of Acyl Phosphonates to Aldehydes Acyl phosphonates have been utilized as new acyl donors for cyanide-catalyzed benzoin type reactions. Cyanation of acyl phosphonates, followed by a 1,2-phosphoryl migration generates the active acyl anion intermediate. This reacts with a variety of aryl aldehydes to yield phosphate ester protected unsymmetrical benzoins in good to excellent yields. The unsymmetrical benzoin product can be obtained after deprotection of the phosphate ester with an aqueous amine solution. III. Conjugate Addition/Ireland-Claisen Rearrangements of Allyl Fumarates: Simple Access to Terminally Differentiated Succinates The conjugate addition of dialkylzinc reagents to allyl fumarates with subsequent Ireland-Claisen rearrangement has been accomplished yielding substituted unsymmetrical succinic acid derivatives. This one-pot reaction creates two new carbon-carbon bonds at contiguous stereogenic centers. The reaction proceeds for several alkylzinc reagents and substituted allyl fumarates. The products contain distinguishable functional handles for further manipulation.
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  • Johnson, Jeffrey
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