Convenient synthesis of 3-aminomethylenedihydrofuran-2-ones

Highly Chemoselective Synthesis of 6‐Alkoxy‐1‐alkyl(aryl)‐3‐trifluoroacetyl‐1,4,5,6‐tetrahydropyridines and 1‐Alkyl(aryl)‐6‐amino‐3‐trifluoroacetyl‐1,4,5,6‐tetrahydropyridines

“…Additionally, only few 1,4,5,6-tetrahydropyridines are described in the literature. [18] Cyclic enones have been extensively used for the last few decades for obtaining a series of heterocyclic compounds such as isoxazoles, [19] pyrazoles, [20] pyrimidines, [21] 3-aminomethylene-dihydrofuran-2-ones, [22] analogues of cyclophosphamide, [23] furan-3-carboxamides [24] and 3-alkoxy-3-cyano carboxylic acids. [25] Although both the synthesis and applications of enones have been the subject of recent reviews, [26] 6-alkoxy-3-trifluoroacetyl-4,5-dihydro-6H-pyrans have been very little explored as starting reagents in organic synthesis.…”

A Convenient Synthesis of 5- and 6-Substituted 2-Phenyl-3H-pyrimidin-4-ones

“…Next, the base removes the H-5, causing the elimination of the alkoxy group leading to the 2-phenyl-3H-pyrimidin-4-ones 2 according to Scheme 2. 15,25 In conclusion, we have described a simple and convenient one-pot procedure for the synthesis of 5-or 6-substituted 2-phenyl-3H-pyrimidin-4-ones from the condensation reaction of 4-alkoxy-1,1,1-trichloroalk-3-en-2-ones with benzamidine hydrochloride, under mild conditions and in good yields. In addition, a simple method to obtain the 6bromomethylpyrimidine, which is an important intermediate for further derivatizations, has been presented.…”

“…To our knowledge, 4-alkoxyvinyl trichloromethyl ketones have not been used for the synthesis of 2-phenyl-3H-pyrimidine-4-ones. The synthetic versatility of 4-alkoxyvinyl trichloromethyl ketones has been recently demonstrated by the preparation of 3aminomethylenedihydrofuran-2-ones, 15 pyrazoles and pyrazolium chlorides, 16 furan-3-carboxylic acids and derivatives, 17 pyrazolecarboxamide, 18 azolylmethylpyrimidin-2-ones, 19 and 4-trichloromethyl-2-methanesulfanyl pyrimidines. 20 The synthesis and applications of 4alkoxy-1,1,1-trichloroalk-3-en-2-ones have also been the subject of a recent review.…”

Improved One-Pot Synthesis of 1-Aryl-3-trifluoroacetyl-1H-pyrroles under Swern Oxidation

“…It is interesting to mention that an enone analogous to 1, but with a trichloromethyl group in the place of the trifluoromethyl, when reacted with primary amines, furnished 3-aminomethylenedihydrofuran-2-ones instead of 1-substituted 3-trichloroacetyl pyrroles, as shown in Scheme 2. 30 This probably happens because the trichloromethyl group is easily eliminated (structure IV) to form a stable lactone, but structure IV, with a trifluoromethyl group in the place of CCl 3 , is not likely to be eliminated and the reaction returns to the structure analogous to III (intermediates 3, Scheme 1), which could be isolated but was not stable enough to be adequately characterized. 23 In summary, we have described the synthesis of a series of new 1-aryl-3-trifluoroacetyl-1H-pyrroles by an improved one-pot, four-step reaction protocol starting from the reac-tion of readily available 3-trifluoroacetyl-4,5-dihydrofuran with arylamines to give 1,1,1-trifluoro-3-(2hydroxyethyl)-4-arylamino-3-buten-2-ones, which were directly submitted to Swern oxidation to furnish 1,1,1-trifluoro-3-(2-ethanal)-4-arylamino-3-buten-2-ones.…”