New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic synclinal model. [reaction: see text]

Monosalts of N-substituted bimorpholine derivatives are efficient organocatalysts in intramolecular and intermolecular aldol reactions. The properties of the catalysts can be tuned either by the selection of an appropriate acid for the salt formation or by the change of a substituent at the nitrogen atom. In aldol condensation, i-Pr-substituted bimorpholine is the most stereoselective catalyst affording products in high yield with enantioselectivities up to 95% ee.

The synthesis of tertiary thiols in enantiomerically enriched form is accomplished by lithiation of enantiomerically enriched N-aryl allylic thiocarbamates. Formation of an allyllithium derivative promotes intramolecular N to C aryl migration to the position α to sulfur, generally with good stereospecificity. The substrates may themselves be obtained by Pd-catalyzed enantioselective [3,3]-sigmatropic rearrangement of N-aryl O-allyl thiocarbamates. Solvolysis of the product thiocarbamates yields tertiary thiols, which may be converted to sulfide derivatives.

The utility of C(2)-symmetric bipiperidine and bimorpholine derivatives as organocatalysts in the Michael addition of enamine intermediates formed from aldehydes to nitroolefins has been demonstrated. The best results were obtained when the reaction was run in the presence of (2R,2'R)-N-iPr-bipiperidine. The products were formed via an enamine intermediate with high diastereo- and enantioselectivity with relatively short reaction times.

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An anchimeric effect of vicinal dimesylate in the intramolecular nucleophilic substitution by amine is described. One sulfonate group of the dimesylate acts as an internal nucleophile and the other as a leaving group, affording meso-bimorpholine in the intramolecular cyclization. w,w¢-Dimesylate omits this effect and the target compound is obtained with high ee.

Aldehydes Q 0320 3,3'-Bimorpholine Derivatives as a New Class of Organocatalysts for Asymmetric Michael Addition. -A new efficient catalyst is developed for the reaction of a variety of aliphatic aldehydes with aromatic nitroolefins and a vinyl sulfone. Sterically hindered aldehydes are unreactive, even after 8 days. Otherwise good yields, good dia-and enantioselectivities are observed. Aliphatic nitroolefin (Vc) reacts stereoselectively but with low yield. -(MOSSE, S.; LAARS, M.; KRIIS, K.; KANGER, T.; ALEXAKIS*, A.; Org. Lett. 8 (2006) 12, 2559-2562; Dep. Org. Chem., Univ. Geneva, CH-1211 Geneva 4, Switz.; Eng.) -R. Steudel 43-083

A general synthesis of highly substituted 2-naphthols based on a new carbanionic reaction sequence is demonstrated. The reaction exploits the dual nature of lithium bases consisting of consecutive ring opening of readily available coumarins with either LiNEt or LiNiPr into Z-cinnamamides, thus generating a directing group in situ and allowing, by conformational freedom, a lateral directed remote metalation for ring closure to give the aryl 2-naphthols in good to excellent yields. These transformations can be combined to provide a more efficient one-pot process. Mechanistic insight into the remote lateral metalation step, demonstrating the requirement of Z-cinnamamide, is described. Application of this methodology to the synthesis of highly substituted 3,3'-diaryl BINOL ligands is also reported.