[3+2] cycloadditions of ynones derived from glycine and (S)-alanine and some other dipolarophiles with azomethine imines, nitrile oxides, diazoacetate, and azidoacetate were studied. The dipolarophiles were obtained from α-amino acids, either by the reduction of the carboxy function with ethynylmagnesium bromide or by propiolation of the amino function. Cu-catalyzed cycloadditions of ynones to azomethine imines were regioselective and gave the expected cycloadducts as inseparable mixtures of diastereomers. In some instances, further oxidative hydrolytic ring-opening took place to afford 3,3-dimethyl-3-(1H-pyrazol-1-yl)propanoic acids. Acid-catalyzed cycloadditions of 3-butenone were also regioselective and provided mixtures of diastereomeric cycloadducts, which were separated by chromatography. In the reactions of title ynones with alkyl diazoacetates, in situ-formed benzonitrile oxides, and tert-butyl azidoacetate, all cycloadducts were obtained as single regioisomers. The structures of all novel compounds were established by nuclear magnetic resonance and X-ray diffraction.
J. A. Joule, K. Mills, Heterocyclic Chemistry, 5th Ed., Wiley-Blackwell, 2010, chapters 30–33, p. 664.
L. Yet, Pyrazoles in Comprehensive Heterocyclic Chemistry III, (Eds.: A. R. Katritzky, C. A. Ramsden, E. F. V. Scriven, R. J. K. Taylor), Vol. 4 (Ed.: J. A. Joule), Elsevier Science Ltd., Oxford, 2008, p. 1.
G. Varvounis, Y. Fiamegos, G. Pilidis, Adv. Heterocycl. Chem.2001, 80, 75.
B. Stanovnik, J. Svete in Science of Synthesis, Houben-Weyl Methods of Molecular Transformations, Vol. 12 (Ed.: R. Neier), Thieme Verlag, Stuttgart, 2002, p. 15.
H. Dorn, Chem. Heterocycl. Compd.1981, 17, 3.
R. M. Claramunt, J. Elguero, Org. Proc. Prep. Int. 1991, 23, 273.
F. Požgan, H. Al Mamari, U. Grošelj, J. Svete, B. Štefane, Molecules2018, 23, 3.
J. Svete, (4R*,5R*)-4-Benzoylamino-5-phenyl-3-pyrazolidinone – A Useful Building Block in the Synthesis of Functionalized Pyrazoles in Stereochemistry Research Trends (Eds.: M. A. Horvat, J. H. Golob), Nova Science Publishers, New York, 2008, chapter 5, p. 129 (Open access item).
U. Grošelj, J. Svete, ARKIVOC2015, Part (vi), 175.
J. Glavač, G. Dahmann, F. Požgan, S. Ričko, B. Štefane, J. Svete, U. Grošelj, Acta Chim. Slov.2017, 64, 715.
J. Elguero, Pyrazoles in Comprehensive Heterocyclic Chemistry II, (Eds.: A. R. Katritzky, C. W. Rees, E. F. V. Scriven), Vol. 3 (Ed.: I. Shinkai), Elsevier Science Ltd., Oxford, 1996, p. 1.
D. Giomi, F. M. Cordero, F. Machetti, Isoxazoles in Comprehensive Heterocyclic Chemistry III, (Eds.: A. R. Katritzky, C. A. Ramsden, E. F. V. Scriven, R. J. K. Taylor), Vol. 4 (Ed.: J. A. Joule), Elsevier Science Ltd., Oxford, 2008, p. 365.
S. Rachwal, A. R. Katritzky, 1,2,3-Triazoles in Comprehensive Heterocyclic Chemistry, (Eds.: A. R. Katritzky, C. A. Ramsden, E. F. V. Scriven, R. J. K. Taylor), Vol. 5 (Ed.: V. V. Zhdankin), Elsevier Science Ltd., Oxford, 2008, p. 1.
C. K. Johnson, M. N. Burnett, Ortep-III (version 1.0.2), Oak Ridge Thermal Ellipsoid Plot Program for Crystal Structure Illustrations, Rep. ORNL-6895, Oak Ridge National Laboratory, Oak Ridge, TN (USA) 1996.
L. J. Farrugia, J. Appl. Crystallogr. 1997, 30, 565.
L. J. Farrugia, J. Appl. Crystallogr.2012, 45, 849.
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