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Reference: Angrish, Deepshikha., (2007). Catalytic transformations via metallocarbenes. DPhil. University of Oxford.Citable link to this page:


Catalytic transformations via metallocarbenes

Abstract: This thesis describes a new catalytic activity of a commonly used metathesis catalyst anddemonstrates the viability of directly coupling two powerful C-C bond forming strategies: cross-metathesisand ylide transformations, both proceeding via metal-catalysed carbene transfer. Catalytic C-C bondformation reactions are highly significant; my studies focus on such transformations involvingmetallocarbenes. Grubbs' 2nd generation Ru catalyst is the most commonly used catalyst in olefinmetathesis to generate thermodynamically preferred trans-olefms. During the course of my studies, Iestablished that Grubbs 2nd generation catalyst (0.5 mol%) can also dimerise diazoacetates to give cis-enediesters(maleates) in good to excellent yields (74-99%) with high stereoselectivity (Z:E>95:5). Thereaction between two different diazoacetates, catalysed by Grubbs catalyst gave access to unsymmetricalcis-enediesters with high stereoselectivity (Z:E>95:5, generally 99:1).The catalyst was found to retain its alkene metathetical activity during diazo coupling; building onthis latter observation a novel route to access dienyl dilactones by head-to-head dimerisation ofunsaturated diazoacetates was developed.Cross-metathesis was found to be chemoselective in the presence of diazo functionality (when flanked by twocarbonyl groups), allowing the functionalisation of tethered olefin. The elaborated diazocarbonyl olefms weresubjected to Rh2(OAc)4 catalysed ylide formation and subsequent transformations. Significantly, one-potcross-metathesis/ylide transformations (1,3-dipolar cycloaddition and [2,3]-simgatropic rearrangement) alsoproved to be viable, establishing that the spent Ru catalyst following metathesis does not affect thesubsequent Rh(II)-catalysed transformation.

Type of Award:DPhil Level of Award:Doctoral Awarding Institution: University of Oxford Notes:This thesis was digitised thanks to the generosity of Dr Leonard Polonsky


Hodgson, D. M. (David M.)More by this contributor



Prof. Dave HodgsonMore by this contributor


 Bibliographic Details

Issue Date: 2007Identifiers

Urn: uuid:dd93e21b-7e8a-44dc-b2f5-49fc670e065c

Source identifier: 603825113 Item Description

Type: Thesis;

Language: eng Subjects: Metathesis (Chemistry) Carbenes (Methylene compounds) Tiny URL: td:603825113


Autor: Angrish, Deepshikha. - institutionUniversity of Oxford facultyMedical Sciences Division - - - - Contributors Hodgson, D. M. David



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