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Enantioselective reactions catalyzed by chiral heterocyclic compounds
Vlašaná, Klára ; Kotora, Martin (advisor) ; Starý, Ivo (referee) ; Sedlák, Miloš (referee)
Novel bis(tetrahydroisoquinoline) N,N'-dioxides 1,2 belong to the group of compounds with axial chirality that act as a Lewis base. These properties make them useful chiral catalysts in reactions such as allylation, opening of epoxides, etc. that exhibit high enantioselectivity. The prepared chiral bis(tetrahydroisoquinoline) N,N'-dioxides (R,Rax,R)-1, (R,Sax,R)-1, (Rax,R)-2 a (Sax,R)-2 were tested as catalysts in enantioselective allylation of variously substituted α,β−unsaturated aldehydes and dienals with allyltrichlorosilane (Scheme 1). All the catalysts exhibited high catalytic activity as well as high asymmetric induction (up to 96% for α,β- unsaturated aldehydes;1 up to 98 % for dienals). Appropriate choice of solvent as a reaction medium3,4 and substitution in α-position in aldehydes were the crucial factors for the successful course of the reaction. The catalytic activity of (R,Rax,R)-1 and (R,Sax,R)-1 was also tested in asymmetric opening of meso-epoxides with tetrachlorosilane (ee up to 69 %) (Scheme 2). N N O O O O 1 N N O O O 2 Scheme 1 Scheme 2 1) Vlašaná, K.; Hrdina, R.; Valterová, I.; Kotora, M. Eur. J. Org. Chem. 2010, 7040. 2) Kadlčíková, A.; Hrdina, R.; Valterová, I.; Kotora, M. Adv. Synth. Catal. 2009, 351,1279. 3) Hrdina, R.; Opekar, F.; Roithová, J.; Kotora, M. Chem. Commun....
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