Asymmetrische organokatalytische Synthesen von hochsubstituierten sechsgliedrigen Carbocyclen und Heterocyclen

The development of new catalytic asymmetric methods for the efficient construction of structurally diverse and highly functionalized carbocycles and heterocycles is an important task. Particularly tandem / domino / cascade and multi-component strategies win lately more and more attention in asymmetric synthesis, based on the concept of organocatalysis. It was shown that it is possible with the help of the non-covalent catalysis, to synthesize cyclohexanes, chromans and tetrahydropyrans asymmetrically. The concept of multi-catalysis has been extended so far that poly-functionalized cyclohexanes are synthesized stereoselectively from beta-keto esters, nitroalkenes, and alpha, beta-unsaturated aldehydes in an one-pot reaction via domino Michael-/Michael-/1,2-addition sequence. The preparation of functionalized chroman derivatives was achieved via a domino-Michael- Hemiacetalization sequence, starting from beta-keto esters, and 2-nitrovinyl phenols. The synthesis of functionalized tetrahydropyrans could also be realized by means of this methodology, wherein alpha-hydroxymethyl nitroalkenes were used