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On the origin of cis selectivity in the cyclization of N-protected 2-substituted 3-aza-5-hexenyl radicals: a density functional study
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för organisk kemi.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för organisk kemi.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för organisk kemi.
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för organisk kemi.
Vise andre og tillknytning
2004 (engelsk)Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 69, nr 5, s. 1487-1491Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Cyclization of the N-dimethylphosphinoyl-2-methyl-3-aza-5-hexenyl radical has been studied at the UB3LYP/6-31+G(d)//UB3LYP/6-31G(d) hybrid density functional level. The corresponding radical precursor has been synthesized and found to give cis/trans ratios of up to 10/1 in reductive radical cyclizations. The relative energies of reactant and transition state conformers were determined. In discord with the Beckwith-Houk model, it has been found that chair-axial transition states, which lead to cis products, are lowest in energy, rationalizing the observed experimental diastereoselectivity.

sted, utgiver, år, opplag, sider
2004. Vol. 69, nr 5, s. 1487-1491
HSV kategori
Identifikatorer
URN: urn:nbn:se:uu:diva-90422DOI: 10.1021/jo030294hPubMedID: 14987001OAI: oai:DiVA.org:uu-90422DiVA, id: diva2:162771
Tilgjengelig fra: 2003-05-12 Laget: 2003-05-12 Sist oppdatert: 2017-12-14bibliografisk kontrollert
Inngår i avhandling
1. Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization
Åpne denne publikasjonen i ny fane eller vindu >>Construction of Five-Membered Heterocyclic Compounds via Radical Cyclization
2003 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis describes how radical cyclization chemistry can be applied for the construction of heterocyclic compounds.

In the first part, a series of electron deficient α-phenylselenenylalkenes were prepared via a PhSeCl-addition/HCl-elimination sequence. Allyl- and propargylamines readily underwent conjugate addition to these species to produce pyrrolidines or dihydropyrrol derivatives, after triethylborane initiated reductive radical cyclization in the presence of tris(trimethylsilyl)silane.

The second part describes a convergent synthesis of the pineal hormone melatonin. The indole nucleus is secured via a tris(trimethylsilyl)silane mediated 5-exo radical cyclization. The protocol provides convenient and simple access to compounds useful for studies of biological activity and structure activity relationships.

The third part describes construction of substituted tetrahydrofuran-3-ones and pyrrolidin-3-ones. Regioselective ring-opening of epoxides or aziridines with benzeneselenolate/tellurolate, followed by Michael addition to electron deficient alkynes afforded the corresponding O/N-vinylated compounds. The tetrahydrofuran-3-ones and pyrrolidin-3-ones were secured via radical carbonylation/reductive cyclization using pressurized carbon monoxide (80 atm).

The fourth part is concerned with the effect of an N-protecting group on the cyclization of 2-substituted-3-aza-5-hexenyl radicals. Relative energies for reactants and transition states were determined using density functional calculations. Reactant and transition state conformers leading to cis-product were lower in energy than those leading to trans-product. The results can be explained by the unfavorable 1,2-strain present in chair-equatorial and boat-equatorial conformers.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2003. s. 59
Serie
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 845
Emneord
Organic chemistry, radical, cyclization, carbonylation, melatonin, pyrrolidine, pyrrolidin-3-one, tetrahydrofuran-3-one, Organisk kemi
HSV kategori
Forskningsprogram
organisk kemi
Identifikatorer
urn:nbn:se:uu:diva-3429 (URN)91-554-5648-0 (ISBN)
Disputas
2003-06-04, B42, BMC, Uppsala, 10:15
Opponent
Veileder
Tilgjengelig fra: 2003-05-12 Laget: 2003-05-12bibliografisk kontrollert

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