- Stereoselectivity of cyclisations via N-acyliminium ions to form pyrido[2′,3′:3,4]pyrrolo[2,1-a]isoindole, -isoquinoline and -benz[c]azepine ring systems
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Pyrido[2′,3′:3,4]pyrrolo[2,1-a]isoindole, -isoquinoline and -benz[c]azepine derivatives are obtained by heating in polyphosphoric acid (PPA) appropriate hydroxy lactam precursors derived from pyridine-2,3-dicarboximides. The stereoselectivity of ring closure is rationalised by considering the development of A(1,3) strain in the cyclisation step from N-acyliminium ion intermediates.
- Bahajaj,Vernon,Wilson
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- Chemoenzymatic synthesis of rivastigmine based on lipase-catalyzed processes
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(Chemical Equation Presented) A straightforward chemoenzymatic synthesis of enantiomerically pure rivastigmine has been efficiently carried out under mild reaction conditions, with Candida antarctica lipase B responsible for the stereoselective acetylation of the corresponding (R)-alcohol or amine. An exhaustive enzymatic study has been developed exploring the possibilities of carry out enzyme recycling, scaling up the enzymatic process and development of a dynamic kinetic resolution procedure for the production of adequate enantiomerically pure precursors of rivastigmine. Total chemoenzymatic synthesis of this pharmaceutical has been performed in good overall yield from commercially available 3-methoxyacetophenone.
- Mangas-Sanchez, Juan,Rodriguez-Mata, Maria,Busto, Eduardo,Gotor-Fernandez, Vicente,Gotor, Vicente
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supporting information; experimental part
p. 5304 - 5310
(2009/11/30)
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