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Ketones intermolecular pinacol coupling reactions

From a synthetic standpoint the intermolecular pinacolic coupling reaction is limited because only homocoupling reactions are generally practical. Cross-coupling reactions mediated by SmF are restricted to specialized, matched partners [35]. Thus a-dicarbonyl compounds can be heterocoupled with aldehydes, providing facile entry to 2,3-dihydroxy ketones. Although selectivities vary, in some cases the diastereoselectivity of the process can be quite high (Eq. 25). [Pg.161]

The 1,5- and 1,6-dialdehydes 22 and 24 undergo the annulative pinacol coupling to give the cyclic vzc-diols 23 and 25, respectively (Scheme 13) [29]. The vanadium-catalyzed intramolecular coupling reaction of 1,5-diketone 26 also proceeds with excellent selectivity (Scheme 14) although the intermolecular coupling of ketones such as acetophenone results in low diastereoselectivity under these conditions [21]. [Pg.73]

The ketyl radical anion intermediates can be exploited in carbon-carbon bond-forming reactions. Intermolecular and intramolecular pinacol couplings between the carbonyl groups of ketones and aldehydes are well known (Chapter 5, Section 5.1), as are intermolecular and intramolecular carbonyl-alkene couplings (Chapter 5, Section 5.2). [Pg.41]

Niobium. Szymoniak has developed a niobium-based method for the pinacol coupling of aliphatic aldehydes, aromatic aldehydes, and aromatic ketones (Eq. 3.18) [37]. In the presence of NbCl3, intermolecular couplings proceed with consistently high diastereoselectivity. In many cases, the diol forms an acetal with the remaining aldehyde, and this is isolated at the end of the reaction. The stereoselection of... [Pg.76]


See other pages where Ketones intermolecular pinacol coupling reactions is mentioned: [Pg.43]    [Pg.272]    [Pg.415]    [Pg.143]    [Pg.272]    [Pg.263]    [Pg.276]    [Pg.178]    [Pg.185]    [Pg.425]    [Pg.477]    [Pg.571]    [Pg.285]    [Pg.137]   


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Intermolecular coupling

Intermolecular pinacol coupling reactions

Intermolecular reactions coupling

Ketones pinacol coupling

Ketones pinacolic coupling reactions

Pinacol

Pinacol coupling reaction

Pinacol couplings intermolecular

Pinacol intermolecular reaction

Pinacol reaction

Pinacolate

Pinacolation

Pinacolic coupling reactions

Pinacolizations

Pinacols

Pinacols coupling

Pinacols ketones

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