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Organocatalysts amine-sulfonamide

Asymmetric addition of diorganozincs to aldehydes and ketones has been reviewed, focusing on bifunctional catalysts such as those prepared from salens or BINOLs. Regioisomeric chiral amine-sulfonamide organocatalysts give >99% yield and up to 98% ee in addition of diethylzinc to aldehydes. Switching between regioisomers effectively switches the direction of selectivity. Amino-acid-derived (15,l 5)-4,4 -biquinazoline primary amines catalyse ethylation of aryl aldehydes in up to 95%... [Pg.39]

Numerous 2-substituted pyrrolidine organocatalysts have been prepared from L-proline and its derivatives, and have been proven to be highly efficient for many asymmetric reactions. Representative organocatalysts have been selected and categorised on the basis of the 2-substituted group that includes di- and tri-amine (la-m), dithioacetal (2a-f), guanidine (2g-i), sulfonamide (3a-j), amide and thioamide (3k-n), urea (4a and 4e), thiourea (4b-d, f-j) and heterocycles such as tetrazole (5a,b), triazole (5c-g), imidazole (5h-j) and benzoimidazole (5k) (Figure 9.1). [Pg.201]

Chen and coworkers screened camphor sulfonamide-derived organocatalysts (3e,f) for the a-amination of aldehydes using dibenzyl azodicarbmgrlate as the amine source. Successive NaBH4 reduction afforded the desired a-aminated alcohols that were obtained in high chemical yields and with excellent enantioselectivities (Scheme 9.43). [Pg.229]

Few chiral secondary amine organocatalysts have been applied to the asymmetric aldol reaction, in 2008. As an example, Maruoka and Kano have designed a binaphthyl-based amino acid, which was applied to induce the asymmetric aldolisation of both acyclic and cyclic ketones with both aliphatic and aromatic aldehydes performed in DMF. ° Remarkable results were obtained in general with enantioselectivities of up to 99% ee for either cyclic or acyclic ketones, which led to the <2 n-products (Scheme 2.41). Furthermore, these authors have used a closely related binapthyl-based amino sulfonamide to promote the cross-aldol reaction between aldehydes, which yielded the corresponding syn products in moderate to high yields (71-91%) and diastereoselectivities (72-90% de) combined with excellent enantioselectivities (94-99% ee). [Pg.102]

Excellent enantioselectivities have also been observed by Maruoka et al. by using several other chiral secondary amines as organocatalysts for the anti-Mannich reaction between various aldehydes and A -protected hnines including a-imino esters. Therefore, the involvement of a chiral binaphthyl-based amino sulfonamide as the organocatalyst allowed a series of UM/i-Mannich products to be obtained from both iV-Boc-protected imines and A -PMP-protected a-tmino esters by reaction with aldehydes. As shown in Scheme 3.12, excellent yields and enantioselectivities (97-99% ee) were observed along with moderate to high anti diastereoselectivities of up to 90% de. [Pg.129]


See other pages where Organocatalysts amine-sulfonamide is mentioned: [Pg.54]    [Pg.132]    [Pg.149]    [Pg.46]    [Pg.50]    [Pg.217]    [Pg.279]    [Pg.796]    [Pg.1034]    [Pg.796]    [Pg.1034]   
See also in sourсe #XX -- [ Pg.39 ]




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Amines sulfonamides

Organocatalysts amine

Sulfonamide organocatalysts

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