Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Copper catalyzed Grignard additions

SCHEME 5. Screening of catalysts and crotonic acid derivatives in the copper-catalyzed Grignard addition. Adapted with permission from Acc. Chem. Res., 40, 179-188 (2007). Copyright 2007 American Chemical Society... [Pg.781]

Ethyl acrylate reacts efficiently under the copper-catalyzed Grignard addition protocol, in which the combination of low temperatures (-20 - -50 C) and catalytic copper(I) chloride (2.6%) was necessary to afford moderate to excellent yields of 1,4-addition products, while elaboration of complex a,(3-unsatu-rated esters is not predictable.91 a In contrast, addition to the a,(3-unsaturated ester (116) affords the... [Pg.92]

Itoh reports that copper-catalyzed Grignard additions to N-tosyl-N-alkyl-a.p-unsaturated amides and N-tosyl-a,(3-unsaturated lactams proceed efficiently while deprotonation occurs exclusively with the corresponding A/-alkyl-a,(3-unsaturated lactams (Scheme 45).94... [Pg.93]

The mechanisms of most of these reactions are not well known. The 1,4 uncatalyzed Grignard reaction has been postulated to proceed by the cyclic mechanism shown, but there is evidence against it. The R2CuLi and copper-catalyzed Grignard additions may involve a number of mechanisms, since the actual attacking species and substrates are so diverse. A free-radical mechanism of some type... [Pg.1119]

Mechanistic aspects of copper-catalyzed Grignard addition to a,/ -unsaturated carbonyl compounds have not attracted much attention, probably because of the complex nature of the reagent system [11], but it would resemble that of the 1,4-addition of stoichiometric or higher-order organocopper reagents that have been investigated extensively [15,18,223]. [Pg.599]

One can indirectly substitute the pyridine ring with electrophiles by using an electron-rich dihydropyridine intermediate. Dihydropyridines 150 can be prepared by a one-pot synthesis utilizing a copper-catalyzed Grignard addition to l-(phenoxycarbonyl)pyridinium chloride (149). Dihydropyridines 150 undergo regiospecific Friedel-Crafts acylation in good yield with many... [Pg.223]

Rolliniastatin-1 was isolated in 1987 from Rollinia mucosa (62), and since then has been found in several species of Annonaceae (4a-b). Koert reported the total synthesis of ew-rolliniastatin-1 110 from L-glutamic acid. The strategy is a sequential synthesis, using as a key step the diastereoselective copper catalyzed Grignard addition on aldehydes (Fig. 12). [Pg.210]

To drive a copper-catalyzed Grignard addition in the 1,6-direction, in the case of dienoates (e.g., 144), a JOSIPHOS-ligated species can be usedJ The parent, JOSIPHOS, as well as Taniaphos, led to very low levels of conversion. However, the reversed JOSIPHOS i.e., a switch between substituents on each phosphorus (143, cf. 136 in Scheme 1-13) gave excellent results regioselectivity >95 5 yields 73-88% ee s 73-96% all p,y-unsaturated (kinetic) products. [Pg.77]


See other pages where Copper catalyzed Grignard additions is mentioned: [Pg.132]    [Pg.940]    [Pg.1030]    [Pg.132]    [Pg.246]    [Pg.132]    [Pg.246]    [Pg.269]    [Pg.802]    [Pg.91]    [Pg.91]    [Pg.132]    [Pg.246]    [Pg.591]    [Pg.75]   
See also in sourсe #XX -- [ Pg.10 , Pg.180 ]




SEARCH



Addition catalyzed

Conjugate addition, copper-catalyzed reactions Grignard reagents

Copper additive

Cyclohexenocycloalkanones via copper catalyzed Grignard addition

Esters (cont copper-catalyzed addition of Grignard

Esters Grignard additions, copper catalyzed

Grignard addition

Prostaglandins via copper catalyzed Grignard additions

Succinaldehyde, 3-alkylmethyl esters synthesis via copper catalyzed Grignard additions

© 2024 chempedia.info