ChemInform Abstract: INTRAMOLECULAR CYCLIZATION IN REACTIONS OF BICYCLIC DIEPOXIDES WITH DIMETHYLAMINE

Abstract

Das Verhalten der Epoxynorbornane (I), (II) und (V) gegenüber Nucle0‐ philen wird am Beispiel der Reaktionen mit Dimethylamin untersucht.

Transformation of oxiranes into other oxygen-containing heterocyclic systems

“…In keeping with the Curtin-Hammett principle, the possibility for molecules to adopt a conformation favorable for formation of activated complexes is especially important in these reactions [70]. [80], which occur chemoselectively with participation of the outer epoxy fragment. [80], which occur chemoselectively with participation of the outer epoxy fragment.…”

Cage-like amino alcohols. synthesis, reactions, and application

“…The aminolysis of both diepoxy derivatives 12 and 16 followed the Krasuskii rule; otherwise, oxabrendane 19 would be obtained from compound 16. Structure 18 rather than 19 was confirmed by considerably more downfield position of the 6-H, 2-H, and 3-H signals in the 1 H NMR spectrum, as compared to the 7-H, 2-H, and 3-H signals in the spectra of oxabrendanes 13 and 15, as well as by the position of the 9-H signal (δ 2.52 ppm, q) which indicated that the 9-H proton is neighboring to nitrogen rather than oxygen atom [45].…”

“…The structure of the major (13, 57-60%) and minor products (14) was confirmed by spectral methods and by comparison with the 1 H NMR spectrum of analog 15 (Scheme 7). Diepoxy derivative 16 of ethylidenenorbornene (a mixture of three stereoisomers, the exo-cis isomer prevailing [47]) reacted under more severe conditions (sealed ampule, 60°C, 3 h); chromatographic separation of the product mixture gave compounds 17 and 18 together with unreacted diepoxide 16 [45] (Scheme 8). The aminolysis of both diepoxy derivatives 12 and 16 followed the Krasuskii rule; otherwise, oxabrendane 19 would be obtained from compound 16.…”

“…Generation in the initial step of nucleophilic hydroxy or amino group at the rear (endo) side of epoxynorbornane is followed by stereoselective attack by nucleophile at the electrophilic carbon atom of exo-epoxynorbornane. Steric strain in the oxetane fragment of compound 18 does not prevent cyclization [45].…”

“…exo-Epoxynorbornane 10 occupies a specific place among alicyclic epoxy compounds due to its high chemical stability in neutral and alkaline media [13,44]. Compound 10 is almost inert toward amines; it does not react with 10 equiv of aqueous dimethylamine on heating for 6 h at 60-150°C [45]; however, prolonged heating with a solution of the same amine in methanol resulted in the formation of amino alcohol 11 as one of the products [46] room temperature into a mixture of several products [45]. The structure of the major (13, 57-60%) and minor products (14) was confirmed by spectral methods and by comparison with the 1 H NMR spectrum of analog 15 (Scheme 7).…”