BINOL catalyzed enantioselective addition of titanium phenylacetylide to aromatic ketones

Chemical Communications

Volumn , Issue 21, 2004, Pages 2448-2449

  Cozzi, Pier Giorgio ^a   Alesi, Silvia ^a  

^a UNIVERSITY OF BOLOGNA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

AROMATIC COMPOUND; KETONE; TITANIUM DERIVATIVE; TITANIUM PHENYLACETYLIDE; UNCLASSIFIED DRUG;

ADDITION REACTION; ARTICLE; CATALYSIS; CATALYST; CHEMICAL MODIFICATION; ENANTIOMER; ENANTIOSELECTIVITY; REACTION ANALYSIS;

EID: 9444271029     PISSN: 13597345     EISSN: None     Source Type: Journal    
DOI: 10.1039/b408654f     Document Type: Article

References (25)

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20. Other BINOL derivatives give the following enantiomeric excesses in the reaction with acetophenone: 3,3′-dibromoBINOL (-15 °C, 7 hours, 63% yield, 62% ee); 6,6′-dibromoBINOL (-15 °C, 18 hours, 86% yield, 75% ee); 5,5′,6,6′,7,7′,8,8′-octahydroBINOL (-15 °C, 18 hours, 72% yield, 30% ee). TADDOL can also be used as active ligand, however, the enantiomeric excess recorded in the model reaction with acetophenone was inferior (-15 °C, 18 hours, 60% yield, 43% ee).
21. The mechanism of the present reaction probably involves a bimetallic titanium complex, in which titanium BFNOL complex acts as a chiral Lewis acid coordinating ketones. For related studies, see: (a) K.-H. Wu and H.-M. Gau, Organometallics, 2004, 23, 580;
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24. Methyl cyclohexyl ketone (-30 °C, 40 hours, 71% yield, 40% ee); allyl methyl ketone (-50 °C, 70 hours, 60% yield, 32% ee).
25. Other aromatic ketones reacted in moderate to high yield and moderate enantioselectivity with our method: butyrophenone (-45 °C, 58% yield, 64% ee); tetralone (-30 °C, 92% yield, 60% ee); 4′-nitroacetophenone (-30 °C, 37% yield, 70% ee); 3′-cyanoacetophenone (-30 °C, 60% yield, 60% ee); acetylfuran (-30 °C, 86% yield, 35% ee).