stereochemistry of organic compounds by d nasipuri pdf free download

Let the four rate constants be k, k, k, and k. Predict the order of the rate constants for the ox. Let 9.19 and 9.20 be the analogues of 9.19 and 9.20, with S, S DIPAMP as the ligand. With R, R DIPAMP as the ligand and methyl-( Z)-acetamido cinamate as the substrate, 9.19 and 9.20 are the major and minor diastereomers, respectively. What metal and ligand combinations are used for the asymmetric hydrogenation of (a) imines, (b) ketones, (c) alkenes with an -acetamido group? What is the combination for cyclopropanation?Īns. Also phosphines are not the best ligands to stabilize Ti 4, Mo 6, etc.ģ. (b) Oxygen atom donors oxidize phosphine to phosphine oxide. (a) Rhodium catalysts for hydrogenation require ligands capable of stabilizing a low oxidation state. 9.2 not used for epoxidation reactions?Īns. 9.1 not used for rhodium-based hydrogenation reactions and (b) ligands of Fig. Noyori, Chemtech, June, 361, 1992, has a one-page description of the stereochemical nomenclatures and rules.Ģ. See chapters on stereochemistry in the books by T. Draw the structures of methyl- ( Z)- and methyl-( E)-acetamido cinamates.Īns.

Give the absolute descriptors (i.e., R and S assignments) to the chiral C atoms in 9.7, 9.8, 9.9, 9.10, 9.15, and 9.18. The chiral binaphthol ligands probably ensure that coordination to La 3 by R CHO is enantioface selective.ġ. Elimination of nitroalcohol takes 9.60 back to 9.12, completing the catalytic cycle.

This process, as shown by curly arrows in 9.60, is facilitated by an interaction between the carbonyl oxygen atom and La 3. The activated CH 2NO 2 moiety thus produced attacks the C atom of the carbonyl group. Conversion of 9.12 to 9.59 is facilitated by the Brønsted base behavior of the Li–O bond and the Lewis acidity of La 3. In 9.59 one of the oxygen atoms of the nitro group coordinates to the La 3 cation. The Li–O bond marked by an arrow in 9.12 is cleaved due to protonation of the binaphthol oxygen atom by nitromethane. The proposed catalytic cycle for the nitroaldol condensation reaction is shown in Fig. The La–O bond marked by an arrow opens up due to protonation of the O atom by nitromethane.

Figure 9.15 Catalytic cycle for asymmetric nitroaldol condensation reaction with 9.12 as the chiral catalyst.

Stereochemistry of organic compounds by d nasipuri pdf free download