Synthesis and gold-catalyzed transformations of allenic compounds

Asikainen, Martta Irmeli (2012) Synthesis and gold-catalyzed transformations of allenic compounds. PhD thesis, University of Nottingham.

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Abstract

This thesis is concerned with the synthesis of allenic compounds and their gold-catalyzed isomerization reactions. Its general aim is the development of new reaction methodologies within these topics and the work has been published in two separate articles. After an introductory chapter (covering relevant literature upto 2010) three separate projects are discussed:

1. Development of tandem enzyme/gold-catalyzed reaction where lipase-catalyzed kinetic resolution of alpha-allenic acetates [R1 2CCCH(CHR2OAc)] (R1,R2 = alkyl) leads to the formation of alpha-hydroxyallenes with 86-99% ee and this transformation is followed by the cycloisomerization of the alpha-hydroxyallenes to the corresponding 2,5-dihydrofurans in a one-pot reaction. It is found that the two transformations work well in one pot except in the case where R2 is branched, which are not hydrolysed.

2. A new approach is developed for the synthesis of allenyl acetates [Ar(R1)CCCH(O2CR2)] (R1 = alkyl, R2 = Me, Ph, t-Bu) using cuprate-mediated SN2’nucleophilic substitution to propargylic dicarboxylates. The reaction was successfull with a range of substrates (11 examples). Investigation on a catalytic variant for the synthesis of the above allenyl acetates. Nickel-catalyzed SN2’ nucleophilic substitution to propargylic dicarboxylates gives the highest selectivity of the desired allenic products but the transformation is not very high-yielding. Attempts towards an asymmetric reaction are thwarted by low enantioselectivities (<22% ee).

3. Comparing the reactivity of propargylic acetates and allenyl acetates (prepared in Sections 2-3) in the gold-catalyzed synthesis of indenes. It was discovered that the allenyl acetates prepared earlier yield indenes with up to quantitative yields and high chemoselectivity, whereas propargylic acetates with terminal a alkyne group only yielded a mixture of cyclization and elimination products.

Item Type:Thesis (PhD)
Supervisors:Woodward, S.
Stockman, R.A.
Faculties/Schools:UK Campuses > Faculty of Science > School of Chemistry
ID Code:2367
Deposited By:Ms Martta Irmeli Asikainen
Deposited On:16 Nov 2012 12:06
Last Modified:16 Nov 2012 12:06

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