The origin of stereoselectivity in cycloaddition reactions promoted by stereoisomers of 8-phenylmenthyl glyoxylate oxime

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Carlos A D Sousa (Author) Other; Carlos F R A C Lima (Author) Other; Mariana Andrade (Author) Other; Xerardo Garcia Mera (Author) Other; Jose E Rodriguez Borges (Author) FCUP

Journal

Title: Tetrahedron

Vol. 69

Pages: 5048-5057

ISSN: 0040-4020

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 6 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-006-A1S

DOI: 10.1016/j.tet.2013.03.033

Abstract (EN): A structural study of three synthesized stereoisomeric oximes, (-)-8-phenylmenthyl glyoxylate oxime (8-PMGO), (+)-8-phenylneomenthyl glyoxylate oxime (8-PnMGO), and (-)-8-phenylisoneomenthyl glyoxylate oxime (8-PinMGO), was performed by means of variable temperature H-1 NMR spectroscopy, X-ray crystallography, and ab initio calculations. It was found that in 8-PMGO a conformation where the phenyl and oxime moieties are stacked is significantly favored, whereas in the other stereoisomers this preference was not so evident. The conformational differences found between the isomers were used to rationalize the outcome of the reaction (simultaneous 1,3-cycloaddition and aza-Diels Alder reaction) between the referred oximes and cyclopentadiene, in which the stereoselectivity was evaluated and found to be nicely reproduced by a simple conformational analysis. The global results indicate that the stereoselectivity of the studied oximes, a bit higher for 8-PMGO, originates from their particular conformational distribution, in which the phenyl. oxime aromatic interaction plays a decisive role.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10