A New Version of Diels-Alder Reaction and Synthetic Studies on Lignans and New OLED Materials

新開發的Diels-Alder反應、植物雌激素-木酚素與新有機發光二極體材料的合成研究

卜項(Prashanth Kumar Amancha)

指導教授 ： 劉行讓

國立清華大學/理學院/化學系/博士(2008年)

https://doi.org/10.6843/NTHU.2008.00127

摘要

In this thesis, chapter-1 reports the total syntheses of three natural products, (±)-4-hydroxycubebinone 1, (±)-5-methoxyclusin 2 and (±)-5'-methoxyyatien 3 as well as (±)-2,3-dibenzylbutyrolactone 56 via novel key intermediate ?-cyano dibezylbutyrolactone. The natural products (±)-1, (±)-2, (±)-3 are EtOAc-soluble fraction of the water extract of Piper cubeba and have shown potent inhibitory activity on the metabolism mediated by CYP3A4.
The total synthesis of (±)-hydroxycubebinone 1 was achieved from ?-cyano butyrolactone 64 arrived at an intramolecular Knoevenagel condensation/ hydrogenation process starting from commercially available syringaldehyde 57. Corey-Fuchs olefination of benzylated 57 (ie 58) followed by double elimination and trapping with para formaldehyde provided alkynol 60 which was then converted to ?-cyano butyrolactone 64 in 4 steps. The alkylation of ?-cyano butyrolactone 64 with 5-methoxy piperonyl bromide furnished (±)-?-cyano dibenzylbutyrolactone (±)-65, followed by removal of benzyl group and subsequent reductive removal of cyano group by using LN gave (±)-hydroxycubebinone 1.
The total syntheses of (±)-5-methoxy clusin 2 and (±)-5'-methoxy yatien 3 was achieved via construction of ?-cyano butyrolactone 73 from intramolecular Knoevenagel condensation/hydrogenation process starting from commercially available 5-methoxy piperonal 67. Corey-Fuchs olefination of 5-methoxy piperonal 67 followed by double elimination and trapping with para formaldehyde provided alkynol 69 which was converted to ?-cyano butyrolactone 73 in 4 steps. The alkylation of ?-cyano butyrolactone 73 with 3,4,5-trimethoxy benzyl bromide furnished (±)-?-cyano dibenzylbutyrolactone (±)-74. Reductive decyanation of lactone (±)-74 by LN furnished (±)-5'-methoxy yatien 3, which yielded (±)-5-methoxy clusin 2 by reduction with DIBAL-H.
The synthesis of (±)-2,3-dibenzylbutyrolactone 56 was achieved from ?-cyano butyrolactone 54 which was obtained from an intramolecular Knoevenagel condensation/hydrogenation process. The Alkylation of ?-cyano butyrolactone 54 with benzyl bromide furnished a new compound (±)-?-cyano-2,3-dibenzylbutyrolactone (±)-55 which on subsequent reductive removal of cyano group using lithium naphthalenide (LN) gave (±)-2,3-dibenzyl butyrolactone 56.
The chapter-2 reports on the successful application of highly substituted 2-cyano acrylates 108~115 as dienophiles in the Diels?Alder cycloaddition reaction to give cycloadducts 116~124. Acrylates 108~115 were readily arrived at by Knoevenagel condensation of an appropriate aldehyde or ketone with cyano ketones 103~107. When commercially unavailable, the requisite cyano ketones were achieved individually by a base-mediated alkylation of the appropriate esters with acetonitrile. Cycloadducts 116~124 were found to be amenable to reductive decyanation using lithium naphthalenide and for a majority of the substrates, the ensuing enolate could be trapped with an alkylating agent. In essence, a very effective and versatile approach to highly substituted cyclohexenes have been developed by taking advantage of the superior dienophilicity of 2-cyano acrylates coupled with propensity of the ?-cyano carbonyl system to undergo reductive alkylation using lithium naphthalenide and an alkylating agent.
The chapter-3 reports on the work towards the development of novel chemical entities suitable for incorporation into organic light emitting diodes (OLEDs) emitting blue-green to yellow light. It reports not only the emission color but also the photoluminescence of Alq3 can be tuned by introduction of ethylthio, ethylsulfonyl, bromo and phenyl groups at different positions of the quinolinolato ring. We synthesized various substituted aluminum quinolato complexes (141, 144, 149, 151, 155, 158, 160) starting from commercially available 8-hydroxyquinoline 137 and O-anisidine 145. Aluminum quinolato complexes 141 and 144 were achieved starting from 8-hydroxyquinoline 137 in 3 and 4 steps respectively whereas the complexes 149, 151, 155, 158, 160 were achieved by Skraup quinoline synthesis of O-anisidine 145 and so on.

關鍵字

Lignans ； Diels-Alder Reaction ； OLED Materials

參考文獻

1. Harworth, R. D. J. Chem. Soc. 1942, 448.

2. Macrae, W. D.; Towers, G. H. N. Phytochemistry 1984, 23, 1207.

3. Ward, R. S. Nat. Prod. Rep. 1999, 16, 75.

4. Ward, R. S. Nat. Prod. Rep. 1997, 14, 43.

5. Ward, R. S. Nat. Prod. Rep. 1995, 12, 183.