the anticoagulant racemic warfarin is synthesized by the michael addition of 4-hydroxycoumarin with benzalacetone in the present of equimolar amounts of imidazolium based ionic liquids [bmim] bf4 and [bmim] br and other reaction solvents such as h2o, pyridine and ammonia in five different tests. also synthesis of a derivative of warfarin (2-methyl-4-phenyl pyrano [3, 2-c] chromen-5(4h)-one) und...

[reaction--see text] The core structure of phomactins C and D was assembled by an efficient strategy starting from 3,4-dimethylcyclohexen-2-one. Key reactions include (1) a high yielding and highly diastereoselective Michael addition of a mixed cuprate, (2) a carbonylative alkyne-enoltriflate coupling or an intramolecular addition of an acetylide onto an aldehyde to form the macrocycle, (3) che...

Silica ferric hydrogensulfate is an efficient heterogeneous catalyst for the cyclization of 2- aminochalcones to the corresponding 2,3-dihydroquinolin- 4(1H)-ones. This intramolecular aza Michael reaction was carried out in high yields using chalcones bearing of electron donating and electron withdrawing groups. The catalyst is reusable without significant decreases in its activity after four t...

The first total syntheses of littoralisone (1) and brasoside (2) have been achieved in 13 overall steps. Both natural products are forged from a common intermediate which is rapidly assembled using organocatalytic technology, including a proline-catalyzed alpha-aminoxylation and a contra-thermodynamic intramolecular Michael addition. Application of the two-step carbohydrate synthesis technology...

Herein, an asymmetric organocatalytic aza-Michael addition reaction of ketimines to nitroolefins is presented. The use 2-hydroxybenzophenone imine improves the enantioselective N-centered nucleophiles nitroalkenes by means intramolecular hydrogen bond formation at moiety. Moreover, versatility process demonstrated under both batch and flow conditions, showing synthesis a large variety nitroamin...

Michael addition–halogenation–intramolecular ring-closing (MHIRC) reactions are processes in which a halogen atom as leaving group can attach to substrates or reactants during the reaction, then undergoes intramolecular ring closure. In this communication MHIRC transformation of 4-benzylidene-3-phenylisoxazol-5(4H)-one and 1,3-dimethylbarbituric acid presence N-bromosuccinimide sodium acetate E...

A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)-(-)-tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r.syn/anti , 99 % eesyn ), whereas using a cinchona alkaloid derived...

An efficient and diastereoselective strategy based on an intramolecular domino aza-Michael/Darzens reaction to synthesize epoxide-fused benzoquinolizidines has been described. Three bonds (1 C-C, 1 C-N and 1 C-O), three rings and three chiral centers can be constructed in a single pot under very mild conditions. All the products were isolated in only one diastereomer with 40-80% yields.

An efficient and enantioselective strategy to synthesize benzoindolizidines from α,β-unsaturated amino ketones via domino intramolecular aza-Michael addition/alkylation was developed. These reactions were enabled by cinchona alkaloid-derived quaternary ammonium salts as the phase-transfer catalyst. A variety of benzoindolizidines were prepared in good yields (up to 93%) and enantioselectivities...