Asymmetric syntheses via metalated chiral hydrazones

N,N-Dialkylhydrazones in Organic Synthesis. From Simple N,N-Dimethylhydrazones to Supported Chiral Auxiliaries

“…Shortly thereafter, Enders developed a very successful approach to the synthesis of enantiomerically pure compounds based on the reactions of chiral N,N-dialkylhydrazones made from carbonyl compounds and prolinol-derived chiral hydrazines known as SAMP and its enantiomer RAMP ( Figure 2). 1,2,48,49,[81][82][83][84] Other chiral hydrazines shown in Figure 2 were developed later for specific purposes.…”

Synthesis of 3,5-O-Benzylidene-2-deoxy-L-riboaldose from 5,5-Dihydroxy-2-phenyl-1,3-dioxane

“…H-NMR (300 MHz, CDCI,): 6 1.59-1.72 ( 1 6 m; H-3), 1.85 (2H, m, 2H-4), 2.01 (IH, m, H-3), 2.50-2.64 (2H, m; H-5, H-I"), 2.77 (IH, m; H-I"),3.10 (IH, d t , J = 9.4, 6.4 Hz; H-S),3.27-3.42 (2H, m; H-I"', H-2),3.37 (3H, s;MeO),3.46 (lH, dd, J = 8.3, 3.5 Hz; H-I"?,4.62 (lH, d , J = 15.4 Hz; H-6'4, 4.63 (IH, ddd, J = 7.3, 4.8, 1.1 HZ; H-47, 4.75 (IH, dd, J = 15.4, 1.lHZ;H-6',),5.10(1H,dm,J=10.2Hz;H-E-3'~,5.16(lH,dm,J=17.2;H-Z-3'~, 5.76 (lH, s, H-27, 6.00 (lH, d d t , J = 17.2, 10.2, 7.0 Hz; H-2'7, 7.33-7.41 (3H, m; Ph), 7.48-7.53 (2H, m; Ph). "C-NMR (300 MHz, CDCb): 6 22.9 (0, 26.8 (C-3), 38.3 (C-I"), 56.0 (C-5), 59.2, 64.8 (C-67, 66.7, 75.4 (C-2'7, 78.0 (C-47, 98.8 (C-27, 117.2 (C-3'7, 126.2 (Ph), 128.3 (Ph), 128.9 (Ph), 134.4 (C-2'7, 138.1 (Ph), 156.4 (C-57.…”

Convenient Synthesis of (3R, 4S)-4-Methyl-3-hexanol and (S)-4-Methyl-3-hexanone, the Pheromones of Ants

“…Consequently, this strategy should be amenable to extrapolation on a practical scale. It is noteworthy that the reported procedures for the synthesis of II [4][5][6] involving asymmetric C-alkylation at the α position of the carbonyl do not give rise to the formation of the product with absolute enantiopurity.…”

“…On the other hand, the ant Manica mutica uses (S)-4-Methyl-3-hexanone (II) as an alarm pheromone [2]. So far a few syntheses of both I [3] and II [4][5][6] have been reported in literature. However, it is observed that both the compounds possess a chiral methyl branching with an α-oxygenated carbon centre that is found in many other natural products.…”