[reaction: see text] The aza-Henry reaction of imines with nitroalkanes was promoted by chiral thiourea with an N,N-dimethylamino group to give beta-nitroamines with good enantioselectivity. Various N-protected imines were examined as substrates. N-Phosphinoylimine gave the best result in terms of chemical yield and enantioselectivity (up to 91% yield, up to 76% ee).

Bifunctional thiourea 1a catalyzes aza-Henry reaction of nitroalkanes with N-Boc-imines to give syn-beta-nitroamines with good to high diastereo- and enantioselectivity. Apart from the catalyst, the reaction requires no additional reagents such as a Lewis acid or a Lewis base. The N-protecting groups of the imines have a determining effect on the chirality of the products, that is, the reaction of N-Boc-imines gives R adducts as major products, whereas the same reaction of N-phosphonoylimines furnishes the corresponding S adducts. Various types of nitroalkanes bearing aryl, alcohol, ether, and ester groups can be used as nucleophiles, providing access to a wide range of useful chiral building blocks in good yield and high enantiomeric excess. Synthetic versatility of the addition products is demonstrated by the transformation to chiral piperidine derivatives such as CP-99,994.

Enantioselective syntheses O 0031 Enantio-and Diastereoselective Michael Reaction of 1,3-Dicarbonyl Compounds to Nitroolefins Catalyzed by a Bifunctional Thiourea. -In this context, a simple route to the antispastic agent (R)-baclofen (XVIII) becomes possible. -(OKINO, T.; HOASHI, Y.; FURUKAWA, T.; XU, X.; TAKEMOTO*, Y.; J. Am. Chem. Soc. 127 (2005) 1, 119-pp; Grad. Sch. Pharm. Sci., Kyoto Univ., Sakyo, Kyoto 606, Japan; Eng.) -Lindner 21-034

Enantioselective syntheses O 0031Enantio-and Diastereoselective Michael Reaction of 1,3-Dicarbonyl Compounds to Nitroolefins Catalyzed by a Bifunctional Thiourea. -The title reagent OATU is found to be a highly efficient catalyst for asymmetric Michael reaction of various 1,3-dicarbonyl compounds with nitroolefins. It allows the generation of a quaternary carbon center with excellent diastereo-and enantioselectivity (to be continued). -(OKINO, T.; HOASHI, Y.; FURUKAWA, T.; XU, X.; TAKEMOTO*, Y.; J. Am.

Amines Q 0120Bifunctional-Thiourea-Catalyzed Diastereo-and Enantioselective aza-Henry Reaction. -Optimized simple conditions are elaborated for the title reaction which is carried out with a broad spectrum of aromatic aldimes and nitroalkanes. Best results are obtained when Boc-substituted imine substrates are used. The versatility of the process is demonstrated by preparation of the optically active piperidines (XVII)(CP-99,994) and (XXI). -(XU, X.; FURUKAWA, T.; OKINO, T.; MIYABE, H.; TAKEMOTO*, Y.; Chem. Eur. J. 12 (2006) 2, 466-476; Grad. Sch. Pharm. Sci., Kyoto Univ., Sakyo, Kyoto 606, Japan; Eng.) -Lindner 20-073

Enantioselective syntheses Enantioselective syntheses O 0031Enantioselective Aza-Henry Reaction Catalyzed by a Bifunctional Organocatalyst. -The aza-Henry reaction of imines with nitroalkanes is smoothly catalyzed by a chiral thiourea derivative (BACTU). It is shown that the enantioselectivity strongly depends on the nature of imine protecting group and that the best results (up to 76% e.e.) are achieved with phosphinoylimines like (Ic) and (IV). -(OKINO, T.; NAKAMURA, S.; FURUKAWA, T.; TAKEMOTO*, Y.; Org. Lett. 6 (2004) 4, 625-627; Grad. Sch. Pharm. Sci., Kyoto Univ., Sakyo, Kyoto 606, Japan; Eng.) -Mischke 25-039