Stereoselective, solid phase-based synthesis of trans 3-alkyl-substituted β-lactams as analogues of cholesterol absorption inhibitors

Synthesis and Modeling of Ezetimibe Analogues

Ezetimibe is a well-known drug that lowers blood cholesterol levels by reducing its absorption in the small intestine when joining to Niemann-Pick C1-like protein (NPC1L1). A ligand-based study on ezetimibe analogues is reported, together with one-hit synthesis, highlighted in the study. A convenient asymmetric synthesis of (2S,3S)-N-α-(R)-methylbenzyl-3-methoxycarbonylethyl-4-methoxyphenyl β-lactam is described starting from Baylis-Hillman adducts. The route involves a domino process: allylic acetate rearrangement, stereoselective Ireland-Claisen rearrangement and asymmetric Michael addition, which provides a δ-amino acid derivative with full stereochemical control. A subsequent inversion of ester and acid functionality paves the way to the lactam core after monodebenzylation and lactam formation. It also shows interesting results when it comes to a pharmacophore study based on ezetimibe as the main ligand in lowering blood cholesterol levels, revealing which substituents on the azetidine-2-one ring are more similar to the ezetimibe skeleton and will more likely bind to NPC1L1 than ezetimibe.

Polymer-Supported Syntheses of Heterocycles Bearing Oxazine and Thiazine Scaffolds

In this review, we summarize synthetic approaches to preparing single or fused oxazine and thiazine derivatives using solid-phase synthesis (SPS). The literature survey revealed that diverse compounds bearing variously functionalized 1,2-oxazine, 1,3-oxazine, or 1,4-oxazine scaffolds and the corresponding thiazines are accessible by SPS. The latest contributions involving the stereoselective polymer-supported syntheses of morpholines indicate that the field is continuing to expand.

Molecular Diversity by Olefin Cross-Metathesis on Solid Support. Generation of Libraries of Biologically Promising β-Lactam Derivatives

The application of the reagent-based diversification strategy for generation of libraries of biologically promising β-lactam derivatives is described. Key features are the versatility of the linker used and the cross-metathesis functionalization at the cleavage step. From an immobilized primary library, diversity was expanded by applying different cleavage conditions, leading to a series of cholesterol absorption inhibitor analogues together with interesting hybrid compounds through incorporation of a chalcone moiety.

Palladium-catalyzed cross-coupling reactions of arylsiloxanes with aryl halides: application to solid-supported organic synthesis

The solid-phase version of the Pd-catalyzed Hiyama reaction between a variety of aryltriethoxysilanes and immobilized aryl halides was developed. Smooth cross-coupling was achieved to afford the corresponding biaryl products in moderate to excellent yields. The described protocol would be particularly useful for the construction of 4'-substituted 1,1'-biphenyl derivatives.