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.
Occhiato
Ernesto G
EG
Dipartimento di Chimica Organica U. Schiff, Polo Scientifico-Università di Firenze, Via della Lastruccia 13, I-50019 Sesto Fiorentino, Italy. ernesto.occhiato@unifi.it
Prandi
Cristina
C
Ferrali
Alessandro
A
Guarna
Antonio
A
D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D006575:Heterocyclic Compounds, 3-Ring / Q000032:analysis / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D015394:Molecular Structure; D011758:Pyrroles / Q000032:analysis / Q000138:chemical synthesis*; D013237:Stereoisomerism
D006575:Heterocyclic Compounds, 3-Ring; D007202:Indicators and Reagents; D011758:Pyrroles; C408872:roseophilin