Regio- und Stereoselektivität bei anionischen Ringöffnungsreaktionen in 2-Azabicyclo[3.2.0]heptan-Derivaten
✍ Scribed by Franzisket, Ludwig ;Heesing, Albert
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1991
- Tongue
- English
- Weight
- 925 KB
- Volume
- 124
- Category
- Article
- ISSN
- 0009-2940
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✦ Synopsis
Regio-and Stereoselectivity in Anionic Ring Opening Reactions of 2-Azabicyclo[3.2.0]heptane Derivatives In the regioselective ring opening of 1 via the dianion 1 c the intermediacy of 2 a is proven by labeling experiments. The regioselective cleavage of the four-membered ring in 3 by LiAlH, proceeds stereoselectively both in the ring and the side chain positions of 4 as shown with deuterated compounds. The regioselectivity is kinetically controlled, the transition state 13 being stabilized by the tendency of lithium ions for complexation.
Bei unseren Untersuchungen zur Umlagerung von bicyclischen Hydroxylamin-Derivaten') fanden wir zwei regiound, im zweiten Fall, zugleich stereoselektive Ringoffnungsarten, die unter der Einwirkung starker Basen ablaufen:
die Offnung der C-l/C-5-Briicke in 2-Azabicyclo[3.2.0]--die Spaltung der C-l/C-7-Bindung in 2-Azabicyclo-hept-6-en-3-on (1) zu 1,3-Dihydro-2H-azepin-2-on (2)"; 13.2.01hept-6-en (3) zu 3-Ethenylpyrrolidin (4).