While several protocols exist for the asymmetric functionalization of pyrazolinones at the α-position relying on nucleophilic addition or annulation procedures, use of α-alkylidene electron-rich analogues in asymmetric vinylogous coupling to carbon electrophiles is substantially an uncharted domain. We now report, for the first time, that alkylidenepyrazolinones carrying an enolizable carbon at the γ-position efficiently participate in direct and asymmetric, catalytic vinylogous Michael-type additions to nitroolefins providing the expected adducts in high yields, with complete γ-site selectivity and with extraordinary levels of enantio-, diastereo-, and geometrical selectivities. Both enantiomeric adducts were equally accessed by employing a quasi-enantiomeric quinine- or quinidine-based thiourea catalyst pair.

Direct and Enantioselective Vinylogous Michael Addition of α-Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual Cinchona Alkaloid Thioureas / G., Rassu; V., Zambrano; L., Pinna; Curti, Claudio; Battistini, Lucia; Sartori, Andrea; Pelosi, Giorgio; Casiraghi, Giovanni; Zanardi, Franca. - In: ADVANCED SYNTHESIS & CATALYSIS. - ISSN 1615-4150. - 356:(2014), pp. 2330-2336. [10.1002/adsc.201300964]

Direct and Enantioselective Vinylogous Michael Addition of α-Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual Cinchona Alkaloid Thioureas

CURTI, Claudio;BATTISTINI, Lucia;SARTORI, Andrea;PELOSI, Giorgio;CASIRAGHI, Giovanni;ZANARDI, Franca
2014-01-01

Abstract

While several protocols exist for the asymmetric functionalization of pyrazolinones at the α-position relying on nucleophilic addition or annulation procedures, use of α-alkylidene electron-rich analogues in asymmetric vinylogous coupling to carbon electrophiles is substantially an uncharted domain. We now report, for the first time, that alkylidenepyrazolinones carrying an enolizable carbon at the γ-position efficiently participate in direct and asymmetric, catalytic vinylogous Michael-type additions to nitroolefins providing the expected adducts in high yields, with complete γ-site selectivity and with extraordinary levels of enantio-, diastereo-, and geometrical selectivities. Both enantiomeric adducts were equally accessed by employing a quasi-enantiomeric quinine- or quinidine-based thiourea catalyst pair.
2014
Direct and Enantioselective Vinylogous Michael Addition of α-Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual Cinchona Alkaloid Thioureas / G., Rassu; V., Zambrano; L., Pinna; Curti, Claudio; Battistini, Lucia; Sartori, Andrea; Pelosi, Giorgio; Casiraghi, Giovanni; Zanardi, Franca. - In: ADVANCED SYNTHESIS & CATALYSIS. - ISSN 1615-4150. - 356:(2014), pp. 2330-2336. [10.1002/adsc.201300964]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2729508
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