Brønsted Acid Catalyzed Highly Diastereoselective Michael‐Type Addition of Azlactones to Enones

Abstract

A highly regio‐ and diastereoselective 1,4‐addition of azlactones to enones catalyzed by a Brønsted acid is described. The Michael adducts were prepared in moderate to good yields and with complete control of the relative stereochemistry. In addition, two consecutive stereogenic centers were created, one of which was a quaternary stereocenter. The method was successfully extended to the first highly diastereoselective desymmetrization of dibenzylidene acetone.

Brønsted Acid-Catalyzed Highly Diastereoselective Michaeltype Addition of Azlactones to Enones

“…Moreover, for the first time, the diastereoselective desymmetrization of dba catalyzed by a Brønsted acid is reported. 3 The development of an enantioselective version as well as mechanisthical investigations are ongoing and will be reported in due course.…”

Brønsted Acid-Catalyzed Dipeptides Functionalization through Azlactones

“…4,5 Due to this versatility, these heterocycles have been extensively employed in a wide scope of transformations, 6 in particular the preparation of quaternary amino acid derivatives. [7][8][9][10][11][12] Different 4-substituted oxazolones are easily available, as this moiety originates from the amino acid precursor 13 or by hydrogenation of the well-known Erlenmeyer azlactones 14 ( Figure 1). However, substituents at position 2 are in most cases restricted to a phenyl or methyl group.…”

Chiral Brønsted Acid Catalyzed Highly Stereoselective Mannich-type reaction of Azlactone with Aldimines

“…1 The organocatalytic version of this reaction presents a series of advantages, such as high yields and enantioselectivities, free-metal catalysts and environment-friendly conditions. 2,3 In this work we report the Mannich-type reaction between azlactone and aldimines, employing a chiral phosphoric acid as organocatalyst.…”