Multifunctional piperidine derivative

By employing the dienamine-catalysis strategy, Chen and coworkers accomplished an unprecedented and highly regio- and stereoselective inverse-electron-demand aza-hetero-Diels-Alder reaction of a,P-unsaturated imines 136 with a,P-unsaturated aldehydes 143 [66]. Various multifunctional piperidine derivatives 144 and 145 can be obtained, with excellent levels of enantioselectivity, that are potentially useful in the synthesis of natural products and medicinal chemistry (Scheme 38.43). 

The use of chiral chloroformates, such as that derived from tranx-2-(a-cumyl)cyclohexanol, allows diastereoselective additions to 4-methoxypyridine. The introduction of a tri-ixo-propylsilyl group at C-3 greatly enhances the diastereoselectivity. The products of these reactions are multifunctional chiral piperidines which have found use in the asymmetric synthesis of natural products. ... 

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