No abstract

1,4-Dihydropyridine (Hantzsch) diesters 3a-e readily undergo metalation at the C-2 methyl (vinylogous ester) position on treatment with alkyllithium bases. The resulting anion intermediates can be treated with electrophilic reagents to afford 1,4-dihydropyridine products that have been chemically elaborated at the C-2 methyl position. The methodology permits a variety of electrophilic functionalities to be regiospecifically introduced at the C-2 methyl position of 1,4-dihydropyridines. Deuterium distribution studies with mixed dihydropyridine amide esters 20a and 20b having nonequivalent C-2 and C-6 methyl groups indicate specific metalation occurs at the C-2 methyl (vinylogous ester) position. Triand tetraanion formation is also possible at both vinylogous methyl and NH positions when the metalation reactions are performed with excess equivalents of n-BuLi or s-BuLi bases.1,4-Dihydropyridine esters (Hantzsch esters 3) represent a potent structural class of therapeutic agents collectively known as calcium antagonists.2 1,4-Dihydropyridine esters 3 can be prepared by Hantzsch condensation reactions between various Knoevenagel-derived adducts l3 and aminocrotonates 2 or their ß-keto ester precursors.4Symmetrical 1,4-dihydropyridine esters 3 (Y = CO2R1, R2

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.