Heck reaction of alkyl halides and α-selective heck reaction of styrenes

My graduate study has been focused on the development of transition metal-catalyzed reactions, especially Pd-catalyzed coupling reactions. In this thesis, we described two catalytic systems that solved challenging problems in the intermolecular Heck reaction. In the first part, we disclosed a new c...

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Main Author: Zou, Yinjun
Other Authors: Steve Zhou
Format: Theses and Dissertations
Language:English
Published: 2014
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Online Access:https://hdl.handle.net/10356/61659
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-616592023-02-28T23:58:36Z Heck reaction of alkyl halides and α-selective heck reaction of styrenes Zou, Yinjun Steve Zhou School of Physical and Mathematical Sciences DRNTU::Science::Chemistry::Organic chemistry My graduate study has been focused on the development of transition metal-catalyzed reactions, especially Pd-catalyzed coupling reactions. In this thesis, we described two catalytic systems that solved challenging problems in the intermolecular Heck reaction. In the first part, we disclosed a new catalyst – Pd/dnpf can efficiently catalyze the Heck reaction of aryl and vinyl triflates with aromatic olefins. In most cases, the aryl or vinyl groups insert selectively at α position in >95% purity and the minor isomers can be removed after purification by flash chromatography. We conducted both experimental and computational study to probe the origin of high internal selectivity. The study revealed that the generality and selectivity is attributed to the combination of electronic and steric effects derived from our new ligand – dnpf. The resulting rigid and congested coordination sphere sterically disfavors the terminal insertion. The initial results of aryl bromides unfolded the potential of the newly-developed ligand for more reactions. In the second part, we disclosed an efficient catalyst – Pd/dppf for the intermolecular Heck reaction of alkyl halides, which is a challenging problem in palladium catalysis. The simple and easily accessible Pd/dppf catalyst showed good reactivity as well as good selectivity. The use of dppf as supporting ligand was crucial for our success in this reaction as other ligands failed to afford the product in a satisfactory yield. It can be applied to a broad spectrum of electrophiles including alkyl iodides, bromides and chlorides. Both primary and secondary alkyl halides bearing functional groups such as esters, amides and nitriles were tolerated in the catalytic system. Concerning the scope of olefins, vinylarenes of steric and electronic perturbations coupled well. We conducted mechanistic study to probe the reaction mechanism and the experimental data suggested that the reaction was initiated by a single electron transfer from Pd(0)-complex to alkyl halides. DOCTOR OF PHILOSOPHY (SPMS) 2014-07-14T01:43:19Z 2014-07-14T01:43:19Z 2014 2014 Thesis Zou, Y. (2014). Heck reaction of alkyl halides and α-selective heck reaction of styrenes. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/61659 10.32657/10356/61659 en 194 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Science::Chemistry::Organic chemistry
spellingShingle DRNTU::Science::Chemistry::Organic chemistry
Zou, Yinjun
Heck reaction of alkyl halides and α-selective heck reaction of styrenes
description My graduate study has been focused on the development of transition metal-catalyzed reactions, especially Pd-catalyzed coupling reactions. In this thesis, we described two catalytic systems that solved challenging problems in the intermolecular Heck reaction. In the first part, we disclosed a new catalyst – Pd/dnpf can efficiently catalyze the Heck reaction of aryl and vinyl triflates with aromatic olefins. In most cases, the aryl or vinyl groups insert selectively at α position in >95% purity and the minor isomers can be removed after purification by flash chromatography. We conducted both experimental and computational study to probe the origin of high internal selectivity. The study revealed that the generality and selectivity is attributed to the combination of electronic and steric effects derived from our new ligand – dnpf. The resulting rigid and congested coordination sphere sterically disfavors the terminal insertion. The initial results of aryl bromides unfolded the potential of the newly-developed ligand for more reactions. In the second part, we disclosed an efficient catalyst – Pd/dppf for the intermolecular Heck reaction of alkyl halides, which is a challenging problem in palladium catalysis. The simple and easily accessible Pd/dppf catalyst showed good reactivity as well as good selectivity. The use of dppf as supporting ligand was crucial for our success in this reaction as other ligands failed to afford the product in a satisfactory yield. It can be applied to a broad spectrum of electrophiles including alkyl iodides, bromides and chlorides. Both primary and secondary alkyl halides bearing functional groups such as esters, amides and nitriles were tolerated in the catalytic system. Concerning the scope of olefins, vinylarenes of steric and electronic perturbations coupled well. We conducted mechanistic study to probe the reaction mechanism and the experimental data suggested that the reaction was initiated by a single electron transfer from Pd(0)-complex to alkyl halides.
author2 Steve Zhou
author_facet Steve Zhou
Zou, Yinjun
format Theses and Dissertations
author Zou, Yinjun
author_sort Zou, Yinjun
title Heck reaction of alkyl halides and α-selective heck reaction of styrenes
title_short Heck reaction of alkyl halides and α-selective heck reaction of styrenes
title_full Heck reaction of alkyl halides and α-selective heck reaction of styrenes
title_fullStr Heck reaction of alkyl halides and α-selective heck reaction of styrenes
title_full_unstemmed Heck reaction of alkyl halides and α-selective heck reaction of styrenes
title_sort heck reaction of alkyl halides and α-selective heck reaction of styrenes
publishDate 2014
url https://hdl.handle.net/10356/61659
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