Stereochemistry and isotope effects in the deuterriation of hindered 2,3-dihydrofurans

✍ Scribed by Estera Touboul; Gilbert Dana; Odile Convert

• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 625 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)89987-7

✦ Synopsis

Abstrat -Reductions by deuterium over W/C were carried out on a series of dihydrofuran caqxnn-&. A stereoselective cis hydrogenation is observed in all cases. The stereochemistry of the dideuteriated products was determined by NOE measurements. According to the steric hindrance of the substituents, dmrteriwn entry is found on the a face or the 6 face of dihydrofuran ring. The formation of mono-or trideuteriated products may occur frcm an exchange reaction between adsorbed hydrogenated and semi-hydrogenated species. An unexpected reverse kinetic isotope effect at C4 is observed, showing a very low vibrationnal energy of atomic hydrogen dissolved in the metal lattice.

(Xlr search for determining comparative parameters for exchange rates and barriers to rotation in phenyl dihydro-and tetrahydrofuran products,' leads us to synthesize or 2c.