The Synthesis of Highly Substituted Isoxazoles by Electrophilic Cyclization:  An Efficient Synthesis of Valdecoxib

Abstract

A large number of functionally-substituted 2-alkyn-1-one O-methyl oximes have been cyclized under mild reaction conditions in the presence of ICl to give the corresponding 4-iodoisoxazoles in moderate to excellent yields. The resulting 4-iodoisoxazoles undergo various palladium-catalyzed reactions to yield 3,4,5-trisubstituted isoxazoles, including valdecoxib.

Convenient Synthesis of Ferrocenylethynyl Ketones via Carbonylative Coupling of Ferrocenylethyne with Aryl Iodides by Using Water as Solvent

“…So always using SDS as surfactant, we further conducted the experiments of the carbonylative coupling of ferrocenylethyne with various aryl iodides at room temperature under a balloon pressure of carbon monoxide for 6 h. The results were listed in the following Table 2. According to Table 2, we found that most of the reactions produce moderate to excellent yields of carbonylative coupling products (entries [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. It seems that the substituted iodides having electron-donating group (entries 1-2, 4-6, 8,11) give better yields than those having electron-withdrawing group (entries 10, [15][16][17][18].…”

“…1 Introduction a, b-Alkynyl ketones have attracted considerable interest as useful intermediates for the synthesis of some biologically active molecules [1] and heterocyclic derivatives [2][3][4], such as pyrroles [5], furans [6,7], furanones [8], triazoles [9], pyrazoles [10], 3,4,5-trisubstituted isoxazoles [11], indolizidinones [12], pyridinones [13], and quinolines [14]. They have also been used in the synthesis of natural products [15], such as chiral propargylic alcohols [16], conjugated dienones [17] and so on.…”

2-Amino-5-sulfanyl-1,3,4-thiadiazoles: A new series of selective cyclooxygenase-2 inhibitors

“…After a few minutes (5)(6)(7)(8)(9)(10), the solution was brought to 0°C in an ice bath and 4-chlorobenzene sulfonamide (ArCl) (0.01 mol, 1.92 g) was added under vigorous stirring. The reaction mixture was checked by thin layer chromatography.…”

Direct nucleophilic C-1 addition of stable isochromenylium tetrafluoroborates under catalyst-free conditions: A new access to 1H-isochromenes

“…They have been known as the proposed inseparable intermediates in a number of cycloisomerization reactions of o-alkynylbenzaldehydes in the presence of metal catalyst or promoters [9][10][11][12][13][14][15][16][17][18][19][20][21] or other electrophiles [22][23][24][25][26][27], until the recent isolation and characterizations of stable isochromenylium salts were achieved by our group [28]. These air-and moisture-stable isochromenylium tetrafluoroborates could be conveniently prepared by direct treatment of the o-alkynylbenzaldehyde precursors with HBF 4 in acetic acid.…”