Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/16388
Title: Organocatalytic reactions of 3-hydroxy-2-pyrone and N-arylsulfonyl-3-hydroxy-2-pyridone
Authors: SOH YING TECK
Keywords: organocatalytic, asymmetric, Diel-Alder, pyridone, amino alcohol, enantioselective
Issue Date: 18-Aug-2009
Source: SOH YING TECK (2009-08-18). Organocatalytic reactions of 3-hydroxy-2-pyrone and N-arylsulfonyl-3-hydroxy-2-pyridone. ScholarBank@NUS Repository.
Abstract: The aim of this study is to develop the asymmetric reactions of 3-hydroxy-2-pyroneand N-arylsulfonyl-3-hydroxy-2-pyridone using chiral organic molecules as catalysts.Chiral amino indanols were easily synthesized in one single step from commerically available materials. They were found to catalyze the Diels-Alder (DA) reactions of Narylsulfonyl-3-hydroxy-2-pyridone with N-substituted maleimides, alkyl vinyl ketones and alkyl acrylates. Good yields were obtained and excellent enantiomeric excess was achieved.The absolute configurations of the products were determined using X-ray analysis.A Michael reaction between N-arylsulfonyl-3-hydroxy-2-pyridone and N2-nitro styrenes was also observed when the amino indanol catalyst was used. The amino indanol can also catalyze the DA reaction of 3-hydroxy-2-pyrone and N-mesityl maleimide, giving high levels of enantiomeric excess for the major product (endo isomer).The addition of different substituents on the 4-position of N-arylsulfonyl-3-hydroxy-2-pyridone was also developed. In one to three steps, different groups such as Cl, Br, allyl, npropyland aryl can be attached smoothly to the 4-position of the pyridone. These newly synthesised pyridones can undergo DA reactions with N-substituted maleimides using the chiral amino indanol as the catalyst. Good yields (up to 95%) and excellent enantioselectivities (up to 94% ee) were also achieved.There are several examples in the literature which made use of the cycloadducts obtained from the DA reactions of 3-hydroxy-2-pyrone and N-arylsulfonyl-3-hydroxy-2-pyridone. The DA products obtained contained several functional groups and chiral centres. Thus, with the asymmetric versions established, they would certainly be useful as reagents in natural product synthesis.
URI: http://scholarbank.nus.edu.sg/handle/10635/16388
Appears in Collections:Ph.D Theses (Open)

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1 Cover.pdf29.15 kBAdobe PDF

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2 Title Page.pdf86.76 kBAdobe PDF

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3 Table of Contents.pdf82.44 kBAdobe PDF

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4 Chapter 1 - BaseDAIntro.pdf177.58 kBAdobe PDF

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5 Chapter 2 3-hydroxy-2-pyrone.pdf370.9 kBAdobe PDF

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6 Chapter 3 3-hydroxy-2-pyridone.pdf328.39 kBAdobe PDF

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7 Chapter 4- Experimental.pdf1.22 MBAdobe PDF

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8 Appendices.pdf815.36 kBAdobe PDF

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9 Publications.pdf7.26 kBAdobe PDF

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