Search

The benzyl imines of several fluorenones were treated with base, followed by methyl chloroformate, to introduce the carbomethoxy group at the 9-fluorenyl position. Imine hydrolysis afforded the title compounds. The reaction was readily conducted on a 30-g scale.

The first examples of spiro[fluorene-9,4'- and -9,5'-isothiazolidin]one dioxides (1 and 2) were synthesized and screened for activity as aldose reductase and L-hexonate dehydrogenase inhibitors. Compared to compounds 1, and 9,5'-compounds 2, synthesized from fluorene-9-sulfonamides by alkylation at C(9) with ethyl bromoacetate followed by cyclization, were more active, but relatively nonselective, inhibitors of aldose reductase and L-hexonate dehydrogenase, with IC50 values for in vitro inhibition of both enzymes on the order of 10(-7)-10(-8) M. However, the isomeric 9,4'-compounds 1, prepared by alkylation of fluorene-9-carboxylic acid esters with bromo- or iodomethanesulfonamide followed by cyclization, were more selective inhibitors of L-hexonate dehydrogenase with IC50 values of about 10(-6) M.

Total syntheses of (±)-21-oxogelsemine (3) and (±)-gelsemine (1) are described. Free radical cyclizations play important roles in constructing the tricyclic core (40 → 41) and oxindole (93 → 96) substructures of the target alkaloids, and an isomerization−cyclization strategy (101 → 102) was used to complete construction of the gelsemine cage. Observations made along the way include intramolecular 1,4- and 1,6-hydrogen atom transfers (64 → 65 and 40 → 47) and a free radical cyclization-fragmentation sequence (85 → 86 + 87). A retroaldol−aldol strategy for adjusting oxindole stereochemistry in gelsemine-like structures is also described (72 → 74 and 86 → 87).

2-Aryl-1-hydroxyazaindoles (pyrrolopylidin-1-ols) are prepared via an oxidation/cyclization of o-hydroxyaminostyrylpyridines with DDQ. Reduction of the N-OH bond affords the corresponding 2-arylazaindoles (1H-pyrrolopyridines). The scope of the cyclization is explored via (i) the condensation of 4-methyl-3-nitropyridine with various aryl aldehydes to afford 2-aryl substituted 6-azaindoles and, (ii) the synthesis of 2-phenyl-4-, 5- and 7-azaindoles.

Aus dem Fluorpicolin (I) und den Aryllithiumverbindungen (II) werden die Arylpicoline (III) hergestellt, die durch Oxidation zu (IV) und anschliesende Cyclisierung in die Ketone (V) ubergefuhrt werden.