Direct and Enantioselective Vinylogous Michael Addition of α‐Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual Cinchona Alkaloid Thioureas. Issue 10 (28th May 2014)

• Record Type: Journal Article
• Authors: Rassu, Gloria; Zambrano, Vincenzo; Pinna, Luigi; Curti, Claudio; Battistini, Lucia; Sartori, Andrea; Pelosi, Giorgio; Casiraghi, Giovanni; Zanardi, Franca
• Is Part Of: Advanced synthesis & catalysis. Volume 356:Issue 10(2014)
• Page Start: 2330
• Page End: 2336
• Publication Date: 2014-05-28
• Subjects: Catalysis -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Chemistry -- Periodicals; Chemistry, Technical -- Periodicals; Chemistry -- Periodicals; Catalysis -- Periodicals; Technology, Pharmaceutical -- Periodicals; 547.2
• DOI: 10.1002/adsc.201300964
• Languages: English
• ISSNs: 1615-4150

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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 <italic>quasi</italic>‐enantiomeric quinine‐ or quinidine‐based thiourea catalyst pair.</p> <p> <boxed-text content-type="graphic" position="anchor" orientation="portrait"> <graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pghnnr48ch" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /> </boxed-text> </p> </abstract>