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Stereoselective Syn...
Stereoselective Synthesis of Amino Alcohols : Applications to Natural Product Synthesis
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- Torssell, Staffan, 1978- (författare)
- KTH,Kemi
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- Somfai, Peter (preses)
- KTH,Kemi
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- Andersson, Pher G, Professor (opponent)
- Institutionen för biokemi och organisk kemi, Uppsala universitet
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(creator_code:org_t)
- ISBN 9789171787347
- Stockholm : KTH, 2007
- Engelska 71 s.
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Serie: Trita-CHE-Report, 1654-1081 ; 2007:52
- Relaterad länk:
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https://kth.diva-por... (primary) (Raw object)
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Abstract
Ämnesord
Stäng
- This thesis is divided into four separate parts with amino alcohols as the common feature. The first part of the thesis describes the development of an efficient three-component approach to the synthesis of α-hydroxy-β-amino esters. Utilizing a highly diastereoselective Rh(II)-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides to various aldimines, syn-α-hydroxy-β-amino esters are formed in high yields and excellent diastereoselectivities. An asymmetric version was also developed by employing chiral α-methylbenzyl imines as dipolarophiles yielding enantiomerically pure syn-α-hydroxy-β-amino esters. This methodology was also applied on a short asymmetric synthesis of the paclitaxel side-chain as well as in an asymmetric synthetic approach towards the proteasome inhibitor omuralide. Furthermore, the use of chiral Rh(II) carboxylates furnishes the syn-α-hydroxy-β-amino esters in moderate enantioselectivity (er up to 82:18), which indicates that the reaction proceeds via a metal-associated carbonyl ylide. The second part describes the development of a 1,3-dipolar cycloaddition reaction of azomethine ylides to aldehydes for the synthesis of α-amino-β-hydroxy esters. Different methods for the generation of the ylides, including Vedejs’ oxazole methology and an Ag(I)/phosphine-catalyzed approach have been evaluated. The best results were obtained with the Ag(I)/phosphine approach, which yielded the desired α-amino-β-hydroxy ester in 68% yield and 3.4:1 syn:anti-selectivity. The last two parts deals with the total synthesis of the amino alcohol-containing natural products D-erythro-sphingosine and (−)-stemoamide. The key transformation in the sphingosine synthesis is a cross-metathesis reaction for the assembly of the polar head group and the aliphatic chain. In the stemoamide synthesis, the key feature is an iodoboration/Negishi/RCM-sequence for the construction of the β,γ-unsaturated azepine core of stemoamide followed by a stereoselective bromolactonization/1,4-reduction strategy for the installation of the requisite C8-C9 trans-stereochemistry.
Ämnesord
- NATURVETENSKAP -- Kemi -- Organisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Organic Chemistry (hsv//eng)
Nyckelord
- Amino alcohol
- asymmetric 1.3-dipolar cycloaddition
- azomethine ylide
- carbenoid
- carbonyl ylide
- cross-metathesis
- omuralide
- oxazolidine
- rhodium
- sphingosine
- stemoamide
- stereoselective synthesis
- total synthesis.
- Organic chemistry
- Organisk kemi
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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