235093-79-5Relevant academic research and scientific papers
A novel synthesis of enantiopure octahydropyrrolo[3,4-b]pyrroles by intramolecular [3 + 2] dipolar cycloaddition on chiral perhydro-1,3-benzoxazines
Pedrosa, Rafael,Andres, Celia,De Las Heras, Laura,Nieto, Javier
, p. 2513 - 2516 (2007/10/03)
(Matrix presented) Condensation of N-substituted glycines with chiral 3-allyl-2-formyl perhydro-1,3-benzoxazines forms an azomethine ylide that cyclizes to give octahydropyrrolo[3,4-b]pyrrole derivatives. The [3 + 2] dipolar cycloadditions are stereoespec
Regio- and stereoselective 5-exo radical cyclizations on a chiral perhydro-1,3-benzoxazine moiety. An access to enantiopure 3-alkylpyrrolidines
Andres, Celia,Duque-Soladana, Juan P.,Pedrosa, Rafael
, p. 4273 - 4281 (2007/10/03)
Both enantiomers of chiral, nonracemic 3-alkyl-substituted pyrolidines are prepared by diastereo-selective 5-exo-trig cyclization on (-)-8- aminomenthol-derived perhydro-1,3-benzoxazines used as chiral auxiliaries, followed by elimination of the menthol appendage. The diastereoselective radical cyclization is promoted by tributyltin hydride and occurs on a 3- aza-5-hexenyl-type radical, leading to five-membered rings in high yield. The stereocontrol of the cyclization is strongly influenced by 1,3-allylic strain so that an appropriate substitution pattern on the olefin-acceptor and the presence of a vicinal stereocenter are crucial for achieving good diastereoselectivity. The enantiopure pyrrolidines are obtained in three steps with concomitant recovering of the starting (+)-pulegone auxiliary.
