asymmetric synthesis

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Post on 13-Apr-2017

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  • DKR

  • Generations in Asymmetric Synthesis1st Generation Substrate-controlled Asymmetric synthesisDiastereoselective reactions where the formation of a chiral centre is controlled by another chiral centre already present in the substrate.2nd generation Auxiliary-controlled Asymmetric synthesisMethods where a chiral auxiliary is covalently attached to the substrate and, through that, controls the asymmetric induction. This strategy, with intermolecular controlled induction, is basically the same in first- and second-generation methods. The difference is the attachment and removal of the auxiliary in the latter.3rd generation Reagent-controlled Asymmetric synthesisThe formation of a new chiral centre is induced by a chiral reagent or catalyst, intermolecularly.4th Generation Catalyst-controlled Asymmetric synthesisCatalytic modifications of the first-, second-, and third-generation methods tend to be considered together with this new fourth-generation. One general procedure involves a reaction of a chiral substrate with a chiral reagent, and is especially useful in reactions where two new stereogenic units are formed stereo selectively in one step.

  • Overview of generations

  • This is what called as 1,2-asymmetric induction2121

  • How does the center control the direction of attack at the triagonal carbon ?Crams Rule

  • Nature is a good chemist. It will give 100% e.e.

  • Any Questions !!!

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