6213-87-2Relevant academic research and scientific papers
Total Synthesis of Asparenydiol by Two Sonogashira Cross-Coupling Reactions Promoted by Supported Pd and Cu Catalysts
Angelici, Gaetano,Carpita, Adriano,Casotti, Gianluca,Evangelisti, Claudio,Ferreri, Matteo,Fusini, Graziano,Pardini, Luca Fidia
, p. 1795 - 1803 (2020/06/08)
Asparenydiol, which is an important natural compound with potential pharmacological activities, was synthesized through two Sonogashira cross-coupling reactions catalyzed by supported Pd and Cu catalysts and by a Mitsunobu etherification. The optimization
Syntheses of the Ethyl Esters of the Plant Host-Selective (H-S) Toxins (AF-IIa, AF-IIc and AK-II) Produced by Pathotypes of Alternaria alternata
Crombie, Leslie,Horsham, Mark A.,Jarrett, Sandra R. M.
, p. 1511 - 1524 (2007/10/02)
Total syntheses of the ethyl esters of the host-selective (H-S) toxins produced by Alternaria alternata (strawberry-type pathogen), AF-IIa and AF-IIc, and by the Japanese pear-type AK-II are reported.The initial synthetic objectives, the 2E,4E,6E, 2E,4Z,6E and 2E,4E,6Z stereoisomers of ethyl 8-hydroxy-9-methyldeca-2,4,6,9-tetraenoate, were attained by the use of acetylene hydrometallation and Pd0-mediated vinyl halide coupling: for this purpose tin chemistry was superior to the use of zirconium compounds.The tetraene-hydroxy esters were epoxidised selectively at the 9,10-double bond by the Sharpless procedure under conditions of kinetic control (50percent reaction), which it was predicted would lead to products of predominantly (8R,9S)-stereochemistry.Esterification of the epoxides produced from the 2E,4E,6E and 2E,4E,6Z hydroxy esters with synthetic (2R,3S)-2-(t-butyldimethylsiloxy)-3-methylpentanoic acid, followed by HPLC separation, gave as the major products, stereoisomers which, after deprotection, were characterised as the ethyl esters AF-toxin IIc and AF-toxin IIa.The stereochemical nature of the minor products in the epoxidations is considered.For the sythesis of the AK-II toxin as its ethyl ester, similar esterification with N-acetyl-L-phenylalanine was carried out, except that the racemisation of the amino acid centre ensued.This led to two major products which were separated and identified as (8R,9S,2'S)- and (8R,9S,2'R)-stereoisomers, the former being identical with the ester of AK-II toxin.
A NOVEL AND EFFICIENT METHOD TO PREPARE 3-(HETERO)ARYL-1-PROPYNES AND ITS APPLICATION TO THE STEREOSELECTIVE SYNTHESIS OF (2E,4E)-N-(2-METHYLPROPYL)-6-(2-METHYLPROPYL)-6-(2-THIENYL)-2,4-HEXADIENAMIDE, PIPEROVATINE AND (E)-N-(2-METHYLPROPYL)-6-(4-METHOXYPHENYL)-4-HEXYN-2-ENAMIDE
Rossi, Renzo,Carpita, Adriano,Lippolis, Vito,Benetti, Massimo
, p. 783 - 791 (2007/10/02)
Chemically pure 3-(hetero)aryl-1-propynes, 13, have been prepared in high overall yields by a novel method which involves: (a) a copper(I)-mediated cross-coupling between a halomethyl(hetero)arene, 16, and trimethylsilylethylmagnesium bromide, 17, to give a trimethylsilyl-3-(hetero)aryl-1-propyne, 18; (b) removal of the trimethylsilyl group from 18 by treatment with potassium fluoride dihydrate in DMF.One of these 1-alkynes, i.e. 3-(2-thienyl)-1-propyne, 13a, has been employed in the key step of a highly stereoselective synthesis of naturally-occurring (2E,4E)-N-(2-methylpropyl)-6-(2-thienyl)-2,4-hexadienamide, 6.On the other hand, 3-(4-methoxyphenyl)-1-propyne, 13b, has been used either in two stereoselective syntheses of another natural N-(2-methylpropyl) amide, i.e. piperovatine, 7, or in the preparation of a structural analogue of 7, i.e. (E)-N-(2-methylpropyl)-6-(4-methoxyphenyl)-4-hexyn-2-enamide, 15.
Palladium-Catalyzed Triethylammonium Formate Reductions. 4. Reduction of Acetylenes to Cis Monoenes and Hydrogenolysis of Tertiary Allylic Amines
Weir, John R.,Patel, Babu A.,Heck, Richard F.
, p. 4926 - 4931 (2007/10/02)
Eight phenyl-conjugated and double bond conjugated acetylenes were reduced with triethylammonium formate and a palladium on carbon catalyst.Cis olefins were obtained in good yields in five examples. 4-Nitrodiphenylacetylene gave only 4-aminodibenzyl and (Z)-methyl non-2-en-4-ynoate gave mainly the E,Z dienoate. 1-Phenyl-3-methylbut-3-en-1-yne gave the cis diene initially, but it isomerized partially under the reaction conditions.Five tertiary allylic amines were shown to undergo hydrogenolysis with the same reducing agent and catalyst to give mixtures of two isomeric olefins in moderate to good yields.
