Le Thanh Giang
Budapest University of Technology and Economics
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Featured researches published by Le Thanh Giang.
Tetrahedron | 1996
Le Thanh Giang; József Fetter; Károly Lempert; Mária Kajtár-Peredy; Ágnes Gömöry
Abstract Treatment of pyrrolidinone 3a with CAN under the usual conditions leads to formation of spiro compound 12, rather than to N-demethoxyphenylation. A study of the reactions of compound 12 with sodium chloride and sodium iodide furnished the proof for our assumption that the related non-isolable compounds 6 and 11 are the intermediates of the anomalous reactions of compounds 1a and 2a, respectively, with CAN.
Tetrahedron | 1999
Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Ferenc Bertha; György M. Keser″u; Gábor Czira; Tibor Czuppon
Abstract The tetrazolyl groups of azetidin-2-ones 1a-e and 1h interfere with the normal reaction of related azetidin-2-ones with lead(IV) acetate, viz. acetoxylation at C-4, and cause formation of tetracyclic products 3a-e and 3h. Similar reactions take place with ring homologues 1f, 1g and 1i, and with open-chain analogues 11a and 11b.
Tetrahedron | 1994
József Fetter; Le Thanh Giang; Tibor Czuppon; Károly Lempert; Mária Kajtár-Peredy; Gábor Czira
Abstract 1-(4-methoxyphenyl)azetidin-2-ones 12 and 13, when treated with cerium(IV) ammonium nitrate (CAN), afford either their N-deprotected derivatives (19, 26) or the chlorinated compounds 22 and 27, respectively, as the main products, depending on whether sodium chloride was present or not. A series of minor products (20, 21, 23–25 and 29, respectively) are formed in addition. 1-(4-Methoxyphenyl)azetidin-2-ones 13 and 14, when treated successively with CAN and sodium iodide, afford the corresponding 1-(4-hydroxyphenyl)azetidin-2-ones 28 and 30, respectively, in good yields. The latter reactions could possibly form the basis for elaboration of a potentially general method for dealkoxy-hydroxylation of N-(2- and 4-alkoxyphenyl)carboxamides. Mechanisms are suggested for the formation of compounds 19 – 30.
Journal of Chemical Research-s | 2003
Ferenc Bertha; Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; K. Lempert; Gábor Czira
In contrast to simple ketones which are stable to CAN, azolyl ketones 3d–3f, 11a, 11b and, in part, 3c and 4c undergo oxidative fragmentation when treated with cerium(IV) ammonium nitrate (CAN).
Journal of Chemical Research-s | 2000
Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Ferenc Bertha; György M. Keserü; Gábor Czira
In contrast to compounds of type 1a, compounds 1c–1i, when treated with lead(IV) acetate or cerium(IV) ammonium nitrate, underwent oxidative cyclizations to afford the corresponding compounds of type 3 with both oxidants, while oxidation of compound 1p afforded compound 2a (m = n = 1).
Journal of Chemical Research-s | 2003
Ferenc Bertha; Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Ildikó Nagy; Gábor Czira
Depending on the nature of the bridge connecting the two hetero rings of the substrates of types 4, 7, 11 and 12 studied, the substrates are attacked by CAN at different sites and, therefore, afford different types of oxidation products.
Journal of The Chemical Society-perkin Transactions 1 | 2001
József Fetter; Ildikó Nagy; Le Thanh Giang; Mária Kajtár-Peredy; Antal Rockenbauer; László Korecz; Gábor Czira
The majority of tetrazolylacetyl derivatives 2 and 7, when treated with lead tetraacetate in dry 1,4-dioxane at room or lower temperature, are oxidized with elimination of molecular nitrogen mainly to the corresponding alkynoyl derivatives 4 and 8, respectively. Vinylidenes (25) have been shown to be the intermediates of the reaction. The reaction does not take place when either the tetrazolyl group is N-substituted or the carbon atom separating the tetrazolyl and the carbonyl groups is disubstituted or these two groups are separated by two carbon atoms as in compound 17. The reaction offers a convenient method for the conversion of 2-cyanoacetyl derivatives into alk-2-ynoyl derivatives via intermediate tetrazolylacetyl derivatives. The 4-methoxyanilide 7o reacts differently, affording the fused heterocyclic compounds 19o and 20o.
Tetrahedron | 1999
Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Gábor Czira
ChemInform | 2010
Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Gábor Czira
ChemInform | 2010
Le Thanh Giang; József Fetter; Mária Kajtár-Peredy; Károly Lempert; Ferenc Bertha; Gyoergy M. Keseru; Gábor Czira; Tibor Czuppon