Stereocontrolled synthesis of polysubstituted piperidines from vinylogous Mannich adducts and aldehydes

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.

A Concise Approach to 2-Azabicyclo[3.3.1]nonane Derivatives from an Acyclic Precursor

[Reaction: see text]. Condensation of a readily available 5-amino-2-alkenoate ester with alpha-unsubstituted aliphatic aldehydes leads to substituted 1,2,3,4-tetrahydropyridines. Subsequent manipulation of the ester and enamine functions gives a quick access to 2-azabicyclo[3.3.1]nonane-containing compounds.