13C NMR Analysis of 3,6-Dihydro-2H-pyrans: Assignment of Remote Stereochemistry Using Axial Shielding Effects

Autor:	Peter T. Northcote, Joanne E. Harvey, Matthias Lein, Mark J. Bartlett
Rok vydání:	2014
Předmět:	Coupling Stereochemistry Chemistry Organic Chemistry Electromagnetic shielding Diastereomer Carbon-13 NMR Ring (chemistry)
Zdroj:	The Journal of Organic Chemistry. 79:5521-5532
ISSN:	1520-6904 0022-3263
DOI:	10.1021/jo500678k
Popis:	The rational analysis of (13)C NMR axial shielding effects has enabled the assignment of remote relative stereochemistry in 3,6-oxygen-substituted 3,6-dihydro-2H-pyrans. Comparison of the (13)C NMR shifts of equivalent centers in cis- and trans-substituted 3,6-dihydro-2H-pyrans allows the relative configuration at the C3 and C6 positions to be defined in diastereoisomeric mixtures. Density functional calculations were used to validate this method and assess the conformational bias present in the ring system. Ultimately, the coupling of computational chemistry with this (13)C NMR-based method provided a reliable and convenient method for stereochemical assignment of a single diastereomer. This approach provides a facile and complementary alternative to the practices previously employed for determining the relative configuration in 3,6-dihydro-2H-pyrans.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::12e0cd41ec8fd0bf0de4d894f88379f0 https://doi.org/10.1021/jo500678k Zobrazit plný text záznamu