Search

The synthesis of 4-substituted indazole derivatives by palladium-mediated cross-coupling reactions was described. Suzuki, Heck, Sonogashira and Stille cross-coupling reactions were used to introduce aryl, vinyl and alkynyl substituents in 4-position of indazole derivatives. The selectivity of bis-Suzuki reactions of 3,4-diiodo- and 3-bromo-4-iodoindazoles was investigated.

3-Iodobenzoic acid was loaded on Rink amide resin. Pd(0) coupling reaction with tributyl(1-ethoxyvinyl)tin followed by bromination using NBS gave an α-bromoketone bound to a solid support. Condensation of thioamide or thiourea, followed by TFA cleavage from the resin, gave 2,4-disubstituted thiazoles or 2-aminothiazoles, respectively. The primary amine of aminothiazole was treated with various acyl or sulfonyl chlorides to provide 2-substituted thiazole analogs.

A short access to 2-carbethoxy-3-(5-imidazolyl)indoles (13, 14, 16), featuring Pd-catalyzed cross coupling between 3-iodoindoles (10–12) and imidazolostannane (9) has been developed. These derivatives when subjected to tandem modified Curtius rearrangement-intramolecular electrocyclization led to the pyridones (19–23) which are key intermediates in the synthesis of the analogs (31), (33) and (36) of the naturally occurring cytoxic α-carbolines grossularines-1 and -2 (1,2).

The modification of natural phosphate (NP) with sodium nitrate by calcination produces an extremely efficient basic catalyst for the Claisen–Schmidt condensation. A large variety of chalcones is easily obtained in high yield at room temperature using only a catalytic amount of NaNO 3 /NP.

The 1-methoxy 1-hydridobicyclophosphorane 1 undergoes oxidation reaction with CCl 4 in basic solutions which allow the replacement of the hydrogen linked to phosphorus by several nucleophile groups. The same reaction carried out with the bicyclophosphorane 8 leads to a new compound 10 in which two P v atoms are included in a ten membered ring.

The Michael addition of nitroalcanes to α,β-unsaturated carbonyl compounds was carried out at room temperature in ethanol, using natural phosphate doped with potassium fluoride.

The synthesis of α-hydroxyphosphonates has been carried out with a high yield at room temperature, using natural phosphate, natural phosphate doped with potassium fluoride and sodium phosphate dodecahydrate without solvents.