Development of Ir- and Rh-Catalyzed Deoxygenation and Carbene Cross Coupling Reactions of Allylic Carbonates

• Author / Creator

  Thomas, Bryce N

• Transition metal-catalyzed allylic substitution reactions are widely used for the selective formation of new bonds. This class of reaction has been extensively studied with a variety of nucleophiles and under optimized conditions that will furnish product in high yield and with high chemo-, regio- and enantioselectivity. However, there remain opportunities for established catalyst systems to facilitate new transformations through the interception of metal π-allyl complexes with novel partners. This thesis describes two reactions of transition metal π-allyl species. The selective deoxygenation of alcohols is a persistent challenge in organic synthesis and a host of methods have been developed to address this problem. The use of [Ir(COD)Cl]2 (COD = 1,5 cyclooctadiene) and [Rh(COD)Cl]2 precatalysts in the presence of a diazene transfer agent, N-isopropylidene-N’-2-nitrobenzenesulfonyl hydrazine (IPNBSH), facilitated the reductive transposition of allylic carbonates with high regioselectivity and good to excellent yield. The reaction proceeded under mild conditions and was highly chemoselective. [Ir(COD)Cl]2 was effective for the deoxygenation of both alkyl and aryl monosubstituted allylic carbonates, including substituents potentially susceptible to decomposition by the transition metal. 1,3-Disubstituted allylic carbonates, including α,β–unsaturated esters, were reduced by [Rh(COD)Cl]2 and P(OPh)3. Interception of a π-allyl fragment by a diazo-generated carbene intermediate gave the net cross coupling 1,3-dieneoate products in good yield, and in some cases, with high selectivity for the thermodynamically disfavored E,Z isomer. Only a single, Ir precatalyst, which has not previously been reported to interact with diazo compounds, gave acceptable yield of product. This observation potentially represents a new mode of activity for a well understood catalyst system.

• Subjects / Keywords

  • Catalysis
  • Carbonates
  • Deoxygenation
  • Cross Coupling
  • Allylic Carbonate
  • Alcohol
  • Chemoselective
  • Rhodium
  • IPNBSH
  • Allylic
  • Reductive
  • Carbene
  • Reduction
  • Allyl
  • Diazo
  • Transition Metal
  • Iridium

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3KW57Z0F

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.