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3.4.2.4.3.1 Addition of Carbonyl Compounds to Enals or Enones via Iminium Catalysis

DOI: 10.1055/sos-SD-206-00122

Mase, N.Science of Synthesis: Water in Organic Synthesis, (20121176.

LUMO-lowering organocatalysis, generally called iminium catalysis, is a powerful methodology for the asymmetric conjugate addition reaction of active methylene compounds 82 to enals and enones 81. (S)-2-{Bis[3,5-bis(trifluoromethyl)phenyl](trimethylsiloxy)methyl}pyrrolidine (77) is a water-compatible catalyst employed in an asymmetric conjugate addition reaction of the β-keto ester 82 (R3=CO2t-Bu; R4=Ac) to (E)-but-2-enal (81, R1=H; R2=Me) in water (Scheme 23).[‌73‌] Similarly, the conjugate addition reaction of dibenzyl malonate (82, R3=R4=CO2Bn) to cinnamaldehyde (81, R1=H; R2=Ph) catalyzed by O-(trimethylsilyl)-protected diphenylprolinol (R)-78 and acetic acid in water occurs at 0°C to room temperature within 24h.[‌74‌] Highly efficient prolinol-based catalyst 79, including a hydrophobic alkyl chain, provides the conjugate addition products 83 in good yields with excellent stereoselectivities in the presence of a large amount of water.[‌75‌] Quinine-based primary amine 80 is a powerful organocatalyst for the aqueous conjugate addition reaction of less reactive enones 81 (R1=R2=alkyl).[‌76‌]

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Meeeeeeeeee 88

M8 M8 M8 M8 Meeeeeeeee ee (%) Meeee (%) Mee
M Me MM8e-Me Me 88 (88eee%), ee, 8e 88 88 [‌88‌]
M Me MM8Me MM8Me 88 (8eee%), MeMM (88eee%), 8°M ee ee, 8e 88e 88 [‌88‌]
M Me MM8 M 88 (8eee%), MeMM (8eee%), ee, 88e 88e 88e [‌88‌]
M Me MM8Me MM8Me 88 (8eee%), MeMM (8eee%), 88°M, 88e 88 88 [‌88‌]
M Me MMM Me 88 (88eee%), MeMM (88eee%), ee, 88e 88e 88e [‌88‌]
Me Me MM8Me MM8 88 (88eee%), MeMM (88eee%), ee, 8e 88e 88e [‌88‌]
Me Me MM8Me MM8 88 (88eee%), MeMM (88eee%), ee, 8.8e 88e 88e [‌88‌]
(MM8)8 MM8Me MM8 88 (88eee%), MeMM (88eee%), ee, 8e 88e 88e [‌88‌]

e Mee M-eeeeee eee eeeeeeee.

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(M)-8-Meeee-8-eeeeeeeeeee-8-ee [Meeeeeeee Meeeeee eeee (M)-8-Meeee-8-eeeeeeeeeeeee (88, M8=M8=M; M8=Me; M8=MM8)]; Meeeeee Meeeeeeee:[‌88‌]

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γ-Meeee Meeeeee 88 (M8=MM8; M8=M); Meeeeee Meeeeeeee:[‌88‌]

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Meeeeee (8M,8M)-8-Meeeee-8-eeeeeeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (88); Meeeeee Meeeeeeee:[‌88‌]

Meeeeeeeeeeeee (8.88eeee) eee eeeee ee e eeee ee eeeeeeee 88 (8.88eeee) ee M8M (8eM). Mee eeeeeee eee eeeeeee eee 88eee eee eeee eeeeeee eeeeeeeeeeeee (88; 8.8eeee) eee eeeee ee eee eeeeeee eee eeeeeeee eee eeeeeeeee ee ee eee 88e. M8M (8eM) eee MM8Me8 (88eM) eeee eeee eeeee, eee eeeeee eeee eeeeeeeee, eee eee eeeeeee eeeee eee eeeeeeeee eeee MM8Me8 (8×88eM). Mee eeeeeeee eeeeeee eeeeeeeee eeee eeeeeeeee, eeeee (Me8MM8), eee eeeeeeee, eee eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeeee/MeMMe 8:8) ee eeeeee eeeeeee (8M,8M)-8-eeeeee-8-eeeeeeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (88); eeeee: 88%.

References


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