Efficient Synthetic Method for β-Enamino Esters Catalyzed by Yb(OTf)3 under Solvent-Free Conditions
作者:Ravi Varala、Sreelatha Nuvula、Srinivas R. Adapa
DOI:10.1071/ch06239
日期:——
esters have been synthesized in moderate to excellent yields by reacting 1,3-dicarbonyl compounds with amines in the presence of catalytic amounts of Yb(OTf)3 (2 mol%). The reaction proceeds smoothly at ambient temperature undersolvent-freeconditions. The catalyst can be recovered and reused.
A General and Efficient Method for the Preparation of β-Enamino Ketones and Esters Catalyzed by Indium Tribromide
作者:Zhan-Hui Zhang、Liang Yin、Yong-Mei Wang
DOI:10.1002/adsc.200505268
日期:2006.1
A variety of β-enaminoketones and esters have been synthesized in high to exellent yields by reacting β-dicarbonyl compounds with amines in the presence of a catalytic amount of indiumtribromide. The reaction proceeds smoothly at room temperature in a short reaction time under solvent-free conditions.
Diastereoselective syntheses of 3-aryl-5-(arylalkyl)-6-methyl-1-(1-phenylethyl)thioxotetrahydropyrimidin-4(1H)-ones: A stereochemical perspective from endo and exocyclic chiral centres
作者:Varun Kumar、Pallepogu Raghavaiah、Shaikh M. Mobin、Vipin A. Nair
DOI:10.1039/c0ob00230e
日期:——
Diastereoselective syntheses of 3-aryl-(S/R)-6-methyl-1-[(S/R)-1-phenylethyl)]-2-thioxotetrahydro pyrimidin-4(1H)-ones were achieved in good yields by the condensation of aryl isothiocyanates with ethyl 3-(1-phenylethylamino)butanoate in a one-pot reaction. Benzylation of these substrates illustrated that the orientations of the exocylic and endocylic groups determine the stereochemical outcome of the product formed.
route to β-enamino esters 1, using accessible starting materials, was developed. Lithiated enamines are allowed to react with diethyl carbonate or benzyl chloroformate with the formation of the β-enamino esters 1a or 1b. The reaction is rather general from a wide array of ketimines and aldimines. Products included cyclic β-enamino esters 1aa-ac, very useful for the synthesis of natural products.
The reduction of homochiral beta-enamino esters 1 with sodium triacetoxyborohydride, which occurs with good diastereo- and enantioselectivity in the beta-amino esters 2, is described. This procedure allows a straightforward preparation of compounds with known biological activity.