Highly Enantioselective Organocatalysis of the Hajos—Parrish—Eder—Sauer—Wiechert Reaction by the β‐Amino Acid Cispentacin.

Abstract

Enantioselective syntheses O 0031Highly Enantioselective Organocatalysis of the Hajos-Parrish-Eder-Sauer-Wiechert Reaction by the β-Amino Acid Cispentacin. -The β-amino acid cispentacin promotes the title reaction with levels of enantioselectivity comparable to or higher than those of proline. -(DAVIES*, S. G.; SHEPPARD, R. L.; SMITH, A. D.; THOMSON, J. E.; Chem. Commun. (Cambridge) 2005, 30, 3802-3804; Chem. Res. Lab., Dep. Chem., Univ. Oxford, Oxford OX1 3TA, UK; Eng.) -M. Paetzel 50-030

Catalytic Enantioselective Desymmetrization Reactions to All-Carbon Quaternary Stereocenters

“…Therefore, much effort has gone into the development of new chiral bifunctional enamine catalysts to improve the efficiency of this important desymmetric reaction. Some notable catalysts are shown in Scheme 4, including βamino acid cispentacin 17, 31 N-substituted bimorpholine derivatives 18, 32 benzimidazole pyrrolidine 19, 33 prolinamide 20, 34 proline-based tripeptide 21, 35 multifunctional N-tosyl-(S)binam-L-prolinamide 22, 36 L-prolinethioamide 23, 37 1,2-cyclohexanediamine-derived primary amine 24, 38 and the trifluor- omethanesulfonic salt of a primary amine 25. 39,40 For a detailed introduction, see the good review by Moyano and Rios.…”

Aspects in the Total Syntheses of Higher Terpenoids Starting From Wieland–Miescher Ketone and Its Derivative: A Review

“…Organocatalysts from other chiral sources for the syntheses of Wieland-Miescher ketone (1). [16][17][18][19][20][21][22][23][24][25][26] Scheme 2. Synthetic study of (±)-aristomakine (30).…”

“…32 Reduction of Wieland-Miescher ketone (1) followed by protection as tertbutyldimethylsilyl (TBS) ether and subsequent bromination provided bromide 46. Subsequent radical bromination with nbromosuccinimide at C-6 followed by dehydrobromination provided 4-bromo-4,6-dienone, which was introduced a formyl equivalent by palladium catalyzed coupling with an oxygenated stannane 47 33 [16][17][18][19][20][21][22][23][24][25][26] Scheme 2. Synthetic study of (±)-aristomakine (30).…”