Biomedical subjects

Alessandro Ferrali

Publications and source records attributed to Alessandro Ferrali.

6 recordsLinked to original sources

PubMed2005

Remote stereocontrol in the Nazarov reaction: a new approach to the core of roseophilin.

Three different procedures are compared to obtain properly substituted divinyl ketones in which one of the double bonds is embedded in a five-membered heterocyclic structure and therefore suitable to produce cyclopenta-fused pyrrole derivatives by the acid-catalyzed Nazarov reaction. These, on treatment with TFA, afforded 2,4-cis-disubstituted 2,3,4,5-tetrahydro-1H-cyclopenta[b]pyrrol-6-ones with high stereocontrol. One of these Nazarov products was oxidized to the corresponding 4,5-dihydro-1H-cyclopenta[b]pyrrol-6-one derivative, thus obtaining an enantiopure key intermediate in the total synthesis of roseophilin.

Catalysis↗

PubMed2005

Synthesis and activity of 8-substituted benzo[c]quinolizin-3-ones as dual inhibitors of human 5alpha-reductases 1 and 2.

Some potent dual inhibitors of 5alpha-reductases 1 and 2, based on the benzo[c]quinolizin-3-one structure and with IC(50) values ranging between 93 and 166nM for both isozymes, were found. The presence of the F atom on the ester moiety at the position 8 was crucial. This result can help in the design of other potent, dual inhibitors to be developed as drugs in the treatment of 5alpha-reductase related diseases.

5-alpha Reductase Inhibitors↗

PubMed2004

New synthetic approach to cyclopenta-fused heterocycles based upon a mild nazarov reaction. 2. Further studies on the torquoselectivity.

Conjugated alkoxytrienes in which one of the double bonds is embedded in a heterocyclic moiety are obtained by the Pd-catalyzed coupling reaction of lactam- and lactone-derived vinyl triflates with alpha-alkoxydienylboronates. These compounds undergo a 4pi electrocyclization process (Nazarov reaction) under acidic conditions and afford cyclopenta-fused heterocycles in good yields. As a continuation of a previous study, the torquoselectivity of this Nazarov reaction has been investigated using 2-alkyl-substituted pyrrolidinone and 2- and 4-substituted delta-valerolactone derivatives. High or complete stereoselectivity has only been observed with the 2-alkyl-substituted heterocycles. Both steric and stereoelectronic effects could contribute to determining the stereoselection of the ring closure.

Journal Article↗

PubMed2004

Synthesis, biological activity, and three-dimensional quantitative structure-activity relationship model for a series of benzo[c]quinolizin-3-ones, nonsteroidal inhibitors of human steroid 5alpha-reductase 1.

New 5alpha-reductase 1 (5alphaR-1) inhibitors were designed to complete a consistent set of analogues suitable for a 3D QSAR study. These compounds were synthesized by a modification of the aza-Robinson annulation, further functionalized by Pd-catalyzed cross-coupling processes, and were tested with human 5alphaR-1 expressed in Chinese hamster ovary 1827 cells. It turned out that the potency of the resulting inhibitors was strongly dependent on the type of substitution at the 8 position, with the IC(50) values ranging from 8.1 to 1050 nM. The construction of this homogeneous set of molecules allowed a 3D QSAR study. In particular, comparative molecular field analysis (CoMFA) was used to correlate the potency of the inhibitors with their physicochemical features. Highly accurate evaluations of the atomic point charges were carried out by means of quantum chemical calculations at the DFT/B3LYP level of theory followed by the RESP fitting procedure. It turned out that increasing the reliability of electrostatic parameters greatly affected the statistical results of the QSAR analysis. The 3D QSAR model proposed could be very useful in the further development of 5alphaR-1 inhibitors, which are suitable candidates to be evaluated as drugs in the treatment of 5alphaR-1 related diseases such as acne and alopecia in men and hirsutism in women.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed2003

New synthetic approach to cyclopenta-fused heterocycles based upon a mild Nazarov reaction.

The Pd-catalyzed coupling reaction of lactam or lactone-derived vinyl triflates and phosphates with alpha-alkoxydienylboronates gives conjugated alkoxytrienes in which one of the double bonds is embedded in a heterocyclic moiety. If subjected to mild acidic hydrolysis, these compounds undergo a 4pi electrocyclization process (Nazarov reaction) which furnishes cyclopenta-fused O- and N-heterocycles in good yields. The scope of the work has been that of closely examining the role and effect of both the heteroatom and the heterocycle ring size on the outcome of the electrocyclization, as well as the torquoselectivity of this process. The presence of the heteroatom was essential in stabilizing the oxyallyl cation intermediate, thus allowing the reaction to occur. The ring size was also a basic parameter in the cyclization step: five-membered azacycles required more drastic conditions to give 5-5 fused systems and did so only after an initial hydrolysis to the corresponding divinyl ketones. As for the torquoselectivity, with both 2-methyl and 4-methyl substituted lactam derivatives steric interactions seem to have a role in forcing the conrotatory process to take place in one sense only: allowing the synthesis of diastereomerically pure compounds to be realized. Because different patterns of substitution on the heterocycle are compatible with the reaction conditions, the methodology developed could be very useful for the synthesis of natural products and biologically active compounds containing cyclopenta-fused O- and N-heterocycle moieties.

Boronic Acids↗

PubMed2002

Synthesis of alpha-acyl-functionalized azacycles by Pd-catalyzed cross-coupling reactions of alpha-alkoxyboronates with lactam-derived vinyl triflates.

Alkoxydienyl- and alkoxystyrylboronates were used for Pd-catalyzed cross-coupling reactions with lactam-derived vinyl triflates. The hydrolysis of the coupling products with alkoxystyrylboronates provided the corresponding alpha-acyl-substituted 3,4-dihydro-(2H)-pyridines and 2,3,4,5-tetrahydroazepines in good to high yields. The hydrolysis of the coupling products with alkoxydienylboronates, performed in the presence of Amberlyst 15, resulted in a Nazarov-type cyclization that afforded hexahydro[1]pyrindin-7-ones and 3,4,5,6,7,8-hexahydro-(2H)-cyclopenta[b]azepin-8-ones. This methodology represents a novel and efficient procedure for the preparation of these classes of azacyclic compounds.

Journal Article↗