Journal article
Effects of α-alkoxy substitution and conformational constraints on 6- exo radical cyclizations of hydrazones via reversible thiyl and stannyl additions
Tetrahedron, Vol.63(38), pp.9373-9381
2007
DOI: 10.1016/j.tet.2007.06.117
PMCID: PMC2034276
PMID: 18797497
Abstract
Access to multifunctional hydrazones of relevance to dysiherbaine synthesis studies is described. Subsequent radical cyclizations of multifunctional hydrazones via a Si- and C-linked tethering strategy are shown to function effectively in 6- exo fashion. Conformational constraints are proposed to play a key role in suppressing unproductive premature reduction pathways. The stereochemical outcomes suggest that minimizing the dipole repulsion between neighboring C N and C–O bonds favors a C α–C( N) dihedral angle placing the C N bond axial within a chairlike transition state, in contrast to the usual Beckwith–Houk model. [Display omitted] Radical 6- exo cyclizations of imino compounds leading to aminosugar building blocks exhibit anomalous diastereoselectivity, attributable to dipole repulsion from an α-alkoxy substituent.
Details
- Title: Subtitle
- Effects of α-alkoxy substitution and conformational constraints on 6- exo radical cyclizations of hydrazones via reversible thiyl and stannyl additions
- Creators
- Gregory K FriestadAlex K Mathies
- Resource Type
- Journal article
- Publication Details
- Tetrahedron, Vol.63(38), pp.9373-9381
- DOI
- 10.1016/j.tet.2007.06.117
- PMID
- 18797497
- PMCID
- PMC2034276
- NLM abbreviation
- Tetrahedron
- ISSN
- 0040-4020
- eISSN
- 1464-5416
- Publisher
- Elsevier Ltd
- Language
- English
- Date published
- 2007
- Academic Unit
- Chemistry
- Record Identifier
- 9983985717902771
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