Asymmetric organocatalytic allylation of acetals

3579 16 48555 7 119203 document 48555 Gleixner_12_PhD.pdf application/pdf 55a593557c780240e63f2c51b2fd2210 MD5 1234392 2016-04-12 07:23:27 http://etheses.bham.ac.uk//id/eprint/3579/1/Gleixner_12_PhD.pdf 3579 1 1 application/pdf application/pdf en public

Gleixner_12_PhD.pdf

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http://eprints.org/relation/isVersionOf http://etheses.bham.ac.uk/id/document/48555 http://eprints.org/relation/isVolatileVersionOf http://etheses.bham.ac.uk/id/document/48555 http://eprints.org/relation/isIndexCodesVersionOf http://etheses.bham.ac.uk/id/document/48555 archive 4031 disk0/00/00/35/79 2012-09-21 09:06:52 2020-01-31 03:40:05 2012-09-21 09:06:52 thesis show 0 Gleixner Renate Maria Cox Liam Simpkins N. S. University of Birmingham Asymmetric organocatalytic allylation of acetals unpub QD 10col_ephy Embargo until January 2016; post-embargo access choice C (for 4 years provisionally and author will confirm the end date later) 12/4/16 The addition of allylmetals to aldehydes, particularly in an asymmetric fashion, is of prime importance in the synthetic chemist’s arsenal of C–C bond-forming methodologies, as the secondary homoallylic alcohol products are primed for further transformations. So far, reagent-controlled approaches with chiral metal-based Lewis acids have been the most effective means for controlling the enantioselectivity of this reaction. However, this approach cannot be used when acetals are employed as the latent electrophiles. Since Brønsted acids also mediate the Hosomi-Sakurai reaction of acetals, we hypothesised that a chiral Brønsted acid HY* has the potential to introduce stereoselectivity into this bond-forming process via the formation of a chiral contact ion pair in which the chiral conjugate base controls the nucleophilic addition to the achiral oxacarbenium ion with which it will be associated. For the investigation, three types of Brønsted acids with different acidity, all based on a binaphthyl core, have been synthesised. These catalysts were employed in the reaction of 1-alkoxyisochromans with allyltrimethylsilane. An optimisation study was carried out and the scope and the limitations of the method were probed. In summary, the first enantioselective asymmetric organocatalytic allylation of acetals is presented. 2012-07 2011-10 graduation eng This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. ubira@lists.bham.ac.uk public 307 University of Birmingham School of Chemistry d_ph na 2012-07 graduation