M. Carmen Sañudo

Synthesis of [1]benzopyrano[4,3-b]pyrrol-4(1H)-ones from N(α)-(2-oxo-2H-1-benzopyran-4-yl)weinreb α-aminoamides

Abstract N(α)-(2-Oxo-2H-1-benzopyran-4-yl)Weinreb-α-aminoamides were prepared from 4-chlorocoumarin and α-aminoacid derivatives. Their reaction with organometallic compounds (RLi or RMgBr) and subsequent cyclization of ketones thus obtained, give [1]benzopyrano[4,3-b]pyrrol-4(1H)-ones. Starting from proline derivatives, simultaneously with the pyranone-pyrrole fusion, we establish an interesting procedure for the formation of pyrrolizines.

Synthesis of silylated β-enaminones and applications to the synthesis of silyl heterocycles

Abstract Silyl β-enaminones have been synthesized by reductive cleavage of silylisoxazoles. These versatile synthons bearing the silyl group in different positions of the enamino ketonic system are of great interest in the construction of a variety of penta- and hexaheterocycles, which, in general, retain the silyl group attached at the ring or in a side chain.

β-Aminoenones in the regioselective synthesis of 1,3,5-trialkylpyrazoles. The influence of the substituents in the mechanism and the regioselectivity of the reaction

β-Aminoenones react with monoalkyl hydrazines to give regioselectively 1,3,5-trisubstituted pyrazoles. The mechanism and level of regioselectivity depend on both the substitution pattern of the substrates and the reaction conditions. When the least bulky substituent is attached at the β-position of the enone, a high regioselectivity is obtained, usually higher than that from equivalent β-diketones. If the β-substituent is the bulkiest group, the regioselectivity decreases. Nevertheless, in the conditions reported in this paper, it is possible to prepare pyrazoles not obtainable from β-diketones.