Effect of lanthanide chloride in the Luche regioselective 1,2-reduction of 1-bromo-11-formyl-nornarwedine (5) was studied. Thus, 1-bromo-11-formyl-nornarwedine ( 5) is reduced with sodium borohydride in the presence of lanthanide chloride to yield 1-bromo-11-formyl-galanthamine isomers ( 6), which is a key intermediate for the commercial production of highly pure galanthamine hydrobromide (1), a modern drug against Alzheimer's disease.
An
improved process for the preparation of solifenacin succinate
(1) involving resolution through diastereomeric crystallization
is described. (1S)-IQL derivative (5) is esterified to form (1S)-ethoxycarbonyl IQL
derivative (6) which is condensed with (RS)-3-quinuclidinol (7) to form a solifenacin diastereomeric
mixture (8); this is subjected to resolution through
diastereomeric crystallization to produce solifenacin succinate (1), which is used for the treatment of an overactive bladder.
A simple and efficient process for the preparation of (±)-9-[(2,3-dihydroxypropoxy)methyl]guanine (isoganciclovir) is described. The synthesis features the preparation of a kinetically and thermodynamically controlled acyclic side chain using masked glycerol and methoxymethyl acetate. The unwanted regioisomers were separated through selective crystallization, which upon deprotection yielded isoganciclovir in good yield. The present work explains the preparation of the acyclic side chain in a simple manner without the aid of any preparative column purification or separation technique.
The Friedel-Crafts acetylation of 5-hydroxyindole derivatives la-c regioselectively produced 6-acetyi-5-hydroxy-indole derivatives 2a-c which were condensed with cinnamic acid using POC! a and dry pyridine to afford 5-einnamoyloxy-6-acetyl-indoles 3a-c. These upon Baker-Venkataraman transformation furnished 6-cinnamoylacetyl-5hydroxyindoles 4a-c which were cyclised separately with AcOH/HCI and Ac20/AcONa to 4H-pyrano-(2,3-f)indol-4-one derivatives 5a-c and 6a-c respectively.Keywords. Friedel-Crafts acetylation of 5-hydroxyindole derivatives; Baker-Venkataraman transformation; 4H-pyrano(2,3-f)indol-4-one derivatives.
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