γ-Amino vinyl sulfoxides in asymmetric synthesis. Synthesis of optically pure α-substituted β-amino nitriles

Oxazolidinones and 2,5-Dihydrofurans via Zinc-Catalyzed Regioselective Allenylation Reactions of l-α-Amino Aldehydes

The simultaneous control of diastereoselectivity and regioselectivity in Zn-catalyzed allenylation reactions of N-protected l-α-amino aldehydes is reported. A reversal in diastereoselectivity could be realized by variation of the α-amino aldehyde protecting groups. A range of 1-allenyl-2-amino alcohols were obtained with excellent regioselectivity and converted to oxazolidinones and dihydrofurans. Many of which could be isolated as single diastereoisomers and without significant erosion of ee, making this a practical catalytic synthesis of highly functionalized heterocycles.

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: a fast and efficient protocol for alcohol oxidation

Hypervalent iodine(III)/TEMPO-mediated oxidation of various aliphatic, aromatic and allylic alcohols to their corresponding carbonyl compounds was successfully achieved by using microreactor technology. This method can be used as an alternative for the oxidation of various alcohols achieving excellent yields and selectivities in significantly shortened reaction times.

Straightforward access to spisulosine and 4,5-dehydrospisulosine stereoisomers: probes for profiling ceramide synthase activities in intact cells

A stereoselective synthesis of spisulosine (ES285) and 4,5-dehydrospisulosine stereoisomers is described. Hydrozirconation of 1-pentadecyne with Schwartz reagent, followed by diastereocontrolled addition to L- or D-alaninal afforded the required 2-amino-1,3-diol framework. The resulting sphingoid bases revealed as excellent probes for the profiling of ceramide synthase activity in intact cells. Among the sphingoid bases described in this work, spisulosine (ES285), RBM1-77, and RBM1-73 were the most suitable ones because of their highest acylation rates. These molecules should prove useful to study the role of the different ceramide synthases and the resulting N-acyl (dihydro)ceramides in cell fate.

Design of structurally rigid trans-diamine-based Tf-amide organocatalysts with a dihydroanthracene framework for asymmetric conjugate additions of heterosubstituted aldehydes to vinyl sulfones

Asymmetric conjugate addition of α-heterosubstituted aldehydes such as α-amido and α-alkoxy aldehydes to vinyl sulfone was effected under the influence of structurally rigid trans-diamine-based Tf-amido organocatalyst (S,S)-2 with a dihydroanthracene framework to furnish α,α-dialkyl(amido)aldehydes and α,α-dialkyl(alkoxy)aldehydes with high enantioselectivity. The chiral efficiency of the structurally unique catalyst (S,S)-2 is apparent in comparison with (S,S)-1 and (S,S)-4 with similar functionality.