A Chemo-Enzymatic Approach to Some Indole and Quinolizidine Alkaloids From Cs -Symmetric Precursors

Authors: Danieli B.; Lesma G.; Passarella D.; Silvani A.

Source: Current Organic Chemistry, Volume 4, Number 2, February 2000 , pp. 231-261(31)

Publisher: Bentham Science Publishers

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Abstract:

In this review we describe the asymmetrization of readily available Cs-symmetric compounds by enzyme-catalyzed reactions to provide chiral building blocks for the effective enantioselective synthesis of certain indole and quinolizidine alkaloids. By the asymmetrization of 1,2-disubstituted cyclo cyclohex-4-enes a series of class I alkaloids, such as (-)-antirhine, (-)-akagerine, and (posative)-meroquinene, have been synthesized from the relevant chiral precursors. By employing the same chemo-enzymatic approach, asymmetrization of Cs-symmetric 3,5-disubstituted piperidines provides access to 15,20-dihydrocleavamine and its analogues, as well as to (posative)-tacamonine. The synthetic design and details of the various syntheses are presented. In addition, the scope and prospects of the symmetrization-asymmetrization strategy are discussed with special reference to the quinolizidine alkaloids.

Keywords: Quinolizidine alkaloids; Symmetric precursors; Class I Alkaloids; Antirhine; Antirhea putaminosa; Akagerine; Meroquinene; Intramolecular michael reactions; Indole alkaloids; Cs symmetric; 3,5 disubstituted; Tacamonine; Piperidines; Wittig or Wittig type; Swern oxidation; Parikh oxidation; Tacamonine