ChemInform Abstract: UNSATURATED CARBONYL‐CONTAINING COMPOUNDS. XXVIII. CYCLOADDITION OF ORGANIC AZIDES TO α‐ACETYLENE KETONES AND ACIDS

Abstract

Cycloadditionen der Azide (II) an die Acetylene (I) in siedendem Methanol (oder DMSO, Dioxan, CC14, Diethylether, Toluol) liefern Gemische der isomeren Triazole (III) und (IV) (angegeben sind die Gemischausbeuten).

The synthesis of novel heterocyclic substituted α-amino acids; further exploitation of α-amino acid alkynyl ketones as reactive substrates

“…Proton NMR spectroscopy (CD 3 OD) indicated that only a single regioisomer 13 was generated with a high chemical shift value (δ H 9.11 ppm) for the C-5 aromatic proton. Assignment of the structure to the 1,4disubstituted regioisomer 13 is consistent with the preferred mode of azide addition to acetylenic ketones as demonstrated by Vereshchagin et al 17 This regiochemistry also accounts for the 1 H NMR spectrum of 13 in which the phenyl substituent interacts with the triazole ring splitting the ortho protons with respect to the meta-para protons. A singlet would have been more likely expected if the phenyl substituent were in the more sterically hindered position adjacent to the carbonyl group, 18 i.e.…”

“…Furthermore, it had been shown that reaction of azides with alkynyl ketones had led to exclusive addition at the acetylene. 17 Thus reaction of 4 with phenyl azide was carried out in refluxing diethyl ether 17 to generate the triazol-4-yl, protected amino acid 13, in high yield (91%) (Scheme 5). Proton NMR spectroscopy (CD 3 OD) indicated that only a single regioisomer 13 was generated with a high chemical shift value (δ H 9.11 ppm) for the C-5 aromatic proton.…”

“…To a solution of 4 (0.120 g, 0.40 mmol) in ethanol (5 ml) was added (Z)-4-aminopent-3-en-2-one 6 (0.040 g, 0.40 mmol) and the resulting mixture was stirred for 48 hours at RT. Flash chromatography (SiO [15], 267 [17] and 223 [12].…”

Kinetics of 1,3-dipolar cycloaddition on the surfaces of Au nanoparticles

“…Our previous report used the general synthetic scheme for producing Au MPCs having multiple functionalities with dipolar cycloaddition shown in Scheme 1 [9]. The yields of the uncatalyzed conversion of azide to triazole were lower on the Au nanoparticles' surfaces than previously reported for reactions in solution or on Au electrodes [16,[21][22][23]. However, later experimentation revealed that the I 2 decomposition and subsequent NMR analysis underestimated the reaction yields.…”