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Permanent link (DOI): https://doi.org/10.7939/R3KW57Z0F

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

Descriptions

Other title
Subject/Keyword
Rhodium
Transition Metal
Catalysis
Reductive
Alcohol
Iridium
Allylic Carbonate
Carbonate
Reduction
Cross Coupling
Diazo
Allyl
IPNBSH
Allylic
Deoxygenation
Carbene
Chemoselective
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Thomas, Bryce N
Supervisor and department
Lundgren, Rylan (Chemistry
Examining committee member and department
Clive, Derrick (Chemistry)
Rivard, Eric (Chemistry)
Department
Department of Chemistry
Specialization

Date accepted
2016-09-21T11:43:44Z
Graduation date
2016-06:Fall 2016
Degree
Master of Science
Degree level
Master's
Abstract
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.
Language
English
DOI
doi:10.7939/R3KW57Z0F
Rights
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. 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.
Citation for previous publication
Lundgren, R. J.; Thomas, B. N. Chem. Commun., 2016, 52, 958—961

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