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1.1.16.1.2.3 Using N-Methylimidazole Nucleophiles with Amino Acids

DOI: 10.1055/sos-SD-204-00330

Hatakeyama, S.Science of Synthesis: Asymmetric Organocatalysis, (20121685.

The reactions of aromatic aldehydes with methyl vinyl ketone using the peptide-based N-methylimidazole nucleophile 37 and l-proline (38) give the enantioenriched products 39 with moderate to high enantioselectivity (up to 81% ee) (Scheme 14).[‌37‌] However, neither l-proline nor the nucleophile 37 alone are effective in promoting the reactions or controlling the enantioselectivity. The combination of d-proline and catalyst 37 is mismatched, and when used leads to the production of the oppositely configured products ent-39 but with poor enantioselectivity. This method can be applied to the intramolecular MoritaBaylisHillman reactions of ω-formylated enones 40 using 1-methylimidazole (41) and (S)-piperidine-2-carboxylic acid [42; l-pipecolic acid]; it affords the (R)-cyclohexenols 43 with moderate to high enantioselectivities and in good yields (Scheme 15).[‌38‌]

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Meeeeeeeeee 88

M8 Meeee (%) eee (%) Mee
8-M8MM8M8 88 88 [‌88‌]
88 88 [‌88‌]
8-M8MM8M8 88 88 [‌88‌]
8-eeeee 88 88 [‌88‌]
8,8-(M8M)8M8M8 88 88 [‌88‌]
8-M8M-8-MeMM8M8 88 88 [‌88‌]
8-M8MM8M8 88 88 [‌88‌]

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Meeeee 88 Meeeeeeeeeeeee Meeeeeeee ee ω-Meeeeeeeee Meeeee Meeee 8-Meeeeeeeeeeeeee eee (M)-Meeeeeeeee-8-eeeeeeeeee Meee[‌88‌]

Meeeeeeeeee 88

M8 Meeeee (%) eee (%) Mee
Me 88 (88) 88 [‌88‌]
8-MeM8M8 88 (88) 88 [‌88‌]
8-MeM8M8 88 (88) 88 [‌88‌]
8-Mee 88 (88) 88 [‌88‌]
8-eeeeeee 88 (88) 88 [‌88‌]

e Meeeee eeeee eeeeeeeeee (>88% eeeeee ee MMM eee MMM eeeeeeee); eeeeee ee eeeeeeeeeee eeee eeeeeeee eeeee eeeee eeeeee eee eeeeee eeeeeeeeeeeeee.

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Meeeeeeeeeee Meeeeeeee

8-[Meeeeee(8-eeeeeeeeeee)eeeeee]eee-8-ee-8-eee (88, M8=8-M8MM8M8); Meeeeee Meeeeeeee:[‌88‌]

Mee eeeeeee 88 (8.8888eeee) ee MMMe8/MMM (8:8; 8.8M), e-eeeeeee (88; 888µe, 8.8888eeee), 8-eeeeeeeeeeeeeeeee (8.8ee, 8.888eeee), eee eeeeee eeeee eeeeee (8.8µM, 8.888eeee), eee ee 88°M, eeee eeeee ee e eeeee-eeeee 88-eM eeeee-eeeeeeee eeeee eeeeeeee eeee e eeeeeee eee. Mee eeeeeeeee eeeeeee eee eeeeeee ee 88°M eeeee eeeeeeee eeee ee eee eeeeeeee eeeeeeee eee eeeeeeee (MMM eeeeeee/MeMMe 8:8), eeee eee eeeeeee eee eeeeeee eeee MMMe8 eee eeeeeeee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeee eee, MMMe8) ee eeeeee e eeee eeeeee eee; eeeee: 8.8ee (88%); 88% ee.

8-Meeeeeeeeeee (M)-8-Meeeeeeeeeeeeee-8-eeee Meeeee (88, M8=8-MeM8M8); Meeeeee Meeeeeeee:[‌88‌]

(M)-Meeeeeeeee-8-eeeeeeeeee eeee (88; 88.8ee, 8.88eeee), M8M (888µM), MMM (888µM), eee e 8.88M eeee ee 8-eeeeeeeeeeeeeee (88) ee MMM (88µM, 8.888eeee) eeee eeeee eeeeeeeeeeee ee e eeeeee eeeeeeeeee eee eeeee 88 (M8=8-MeM8M8; 888ee, 8.88eeee). Mee eeeeeee eee eeeeeee ee ee eee 88e, eee eee eeeeeeeee eeeeee eeee eee eeeeee eeee MeMMe (88eM), eee eeeeee ee eeee eeee eee. ee MM8Me, eee. ee MeMMM8, eee eeeee. Mee eeeeeee eeeee eee eeeee (Me8MM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeeeee e eeee eeeeee eee; eeeee: 888ee (88%). Mee eeeeeee eeeeeeee ee eeee eeeeee eeeeeeee ee ee e eeeeee eeeeeeee eeee eeeeee eeeeeeeeee eeeeeeeeee ee eee-eeeeeeeee eeeee ee eee eeeeeeee ee eee 8MMMM eeeeeeee. Meee eeeeeeee eee eeeeeeee eeeeeee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee/MeMMe 888:8 ee 8:888) eeeeeeeee eee eeeee eeeeeeee ee e eeeee eee; eeeee: 88ee (88%); 88% ee.

References


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