Enantiomerically pure β-aminoalcohols, produced through an organocatalytic Mannich reaction, were subjected to an Ugi multicomponent reaction under classical or Lewis acid-promoted conditions with diastereoselectivities ranging from moderate to good. This approach represents a step-economical path to enantiomerically pure, polyfunctionalized peptidomimetics endowed with three stereogenic center...

3 Starting from 2-methyl-4-nitro-imidazole, new 5-(2-methyl- 4-nitro-1-imidazomethyl)-1,3,4-oxadiazole-2-thione () was synthesized and was subjected to Mannich reaction with appropriate amines to yield a new series of 3-substituted aminomethyl-5-(2-methyl-4-nitro-1-imidazomethyl)- 1,3,4-oxadiazole-2-thiones (4a-j). The structure of the title compounds was elucidated by elemental analysis and sp...

A stereoselective approach to the 8b-azaacenaphthylene ring system is described. This new route features a dichloroketene-enol ether [2 + 2] cycloaddition, a vinylogous Mannich reaction, and an aza-Prins cyclization as key stereoselective transformations.

A new series of Mannich bases MK8-12 has been synthesized from 1, 2, 4thiadiazole by Mannich reaction. All the synthesized compounds of the series displayed, remarkable analgesic activity in comparison to standard drug diclofenac sodium. In the synthesized thiadiazole derivatives MK-8 & MK-10 showed activity at 20mg/kg . MK-9 & MK-11 are considered as most active compounds as they protected 60....

Organocatalytic Mannich addition of aldehydes to a formaldehyde-derived iminium species catalyzed by proline-derived chiral pyrrolidines provides beta-amino aldehydes with >/=90% ee. Mechanistic analysis of the proline-catalyzed reactions suggests that non-hydrogen-bonded ionic interactions at the Mannich reaction transition state can influence stereochemical outcome. The beta-amino aldehydes f...

Sulfonated polystyrene/montmorillonite nanocomposite (OMMT/PS-SO3H) was prepared and used as a novel, efficient and inexpensive heterogeneous acid catalyst in the one-pot reaction three-component Mannich reaction of ketones, aromatic aldehydes and amines under solvent-free conditions. The catalyst was characterized by XRD, SEM, TG, BET and FT-IR techniques. This method has advantages...

Organic base-catalyzed reaction of (S)-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine with dialkyl malonates was found to be effective for synthesis of both (S,S(S)) and (R,S(S)) β-aminomalonates in high yield with good to excellent diastereoselectivity (76-98% de). The products of this Mannich reaction provide direct access to β-trifluoromethyl-β-alanine of either (R) or (S) absolute conf...

An efficient one-pot nitro-Mannich/hydroamination cascade reaction for the synthesis of substituted pyrrolidines bearing three stereocentres is reported. Proceeding under the control of a combination of base and gold(I) catalysts, the cascade reaction affords the pyrrolidine products in high yields with good to excellent diastereoselectivities.

A concise sequence utilizing a Petasis three component reaction followed by a tandem aza-Cope-Mannich cyclization afforded novel polycyclic heterocycles in good yield; alternative iminium cyclization based on a Pictet-Spengler reaction or aminal formation led to divergent pathways affording skeletal diversity.

[reaction: see text] The cinchona alkaloids catalyze direct asymmetric Mannich reactions of cyclic 1,3-dicarbonyl compounds with acyl imines to afford alpha-quaternary carbon-bearing reaction products in yields of up to 98%, a diastereomeric excess of 90% or greater, and enantioselectivities up to 99% ee. A model is proposed that accounts for both the observed diastereoselectivities and the ena...