Reactions of Nitrosonium Ethyl Sulfate with Olefins and Dienes: An Experimental and Theoretical Study Nikolai V. Zyk, Evgueni E. Nesterov, Andrei N. Khlobystov, and Nikolai S. Zefirov* Department of Chemistry, Moscow State University, 119899 Moscow, Russian Federation Loren A. Barnhurst and Andrei G. Kutateladze* Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208 Received April 22, 1999 Nitrosonium ethyl sulfate (1), which is generated in situ from ethyl nitrite and sulfur trioxide, is a convenient reagent for the one-pot transformation of olefins and dienes into substituted aldehydes and ketones. New experimental and theoretical aspects of this reaction are discussed. A DFT and ab initio computational study is undertaken to provide further insight into the mechanism of electrophilic nitrosation, including the initial π-complexes, transition states, and the intermediates involved in subsequent carbonyl formation. Electrophilic addition across olefinic double bonds is a fundamental process in organic chemistry that has both theoretical value and far-reaching synthetic applications. Indisputably, the Ad E reaction of olefins constitutes a versatile and reliable method for their functionalization, making the search for new electrophilic reagents, as well as the development of methods to enhance the reactivity of weak electrophiles, an important task. 1-3 In recent years, we have proposed a number of new electrophilic reagents based on the novel concept involv- ing activation of weak electrophiles with sulfur trioxide. 4 In a previous paper 5 we reported the application of this concept to the electrophilic addition of ethyl nitrite to cycloalkenes. This paper contributes an important syn- thetic development of this idea augmented with density functional theory (DFT) and ab initio theoretical studies to better understand the mechanism of nitrosation. Results and Discussion Earlier we found 5 that ethyl nitrite reacts instantly with an equimolar amount of SO 3 at -50 to -30 °C in CH 2 Cl 2 to give a highly reactive nitrosating reagent, nitrosonium ethyl sulfate (1), which was used in situ without purification or isolation. Reagent 1 reacts with cyclic olefins to form R-ethylsulfato cycloalkanones 2 in good yields. As a development of this idea we now report the results of our experimental and theoretical studies on the reactions of 1 with terminal olefins and dienes. In the case of 1-hexene (3a), 1-heptene (3b), and 1-octene (3c) the reaction furnished the corresponding R-ethylsulfato- substituted aldehydes 4a-c in good yields (70-75%). The reactions proceed regiospecifically in accordance with the Markovnikov rule. It should be emphasized that the above reaction of 1 is a rare case of direct conversion of the terminal olefinic carbon into the aldehyde group. (1) (a) Schmid, G. H. Electrophilic addition to carbon-carbon double bonds. In Chemistry of Double-Bonded Functional Groups; Patai, S., Ed.; Wiley: Chichester, U.K., 1989; Vol. 2, Part 1, p 679. (b) Freeman, F. Chem. Rev. 1975, 75, 439. (c) Fahey, R. C. Top. Stereochem. 1968, 3, 237. (2) (a) Zefirov, N. S.; Zyk, N. V.; Kolbasenko, S. I.; Kutateladze, A. G. J. Org. Chem. 1985, 50, 4539 and references therein. (b) Smit, V. A.; Zefirov, N. S.; Bodrikov, I. V.; Krimer, M. Z. Acc. Chem. Res. 1979, 12, 282. (3) For selected recent examples, see: (a) Stavber, S.; SotlerPecan, T.; Zupan, M. Bull. Chem. Soc. Jpn. 1996, 69, 169. (b) Pitre, S. V.; Reddy, M. V. R.; Vankar, Y. D.; Madhusudanan, K. P. Synth. Commun. 1997, 27, 267. (c) Sanseverino, N. M.; de Mattos, M. C. S. Synthesis 1998, 1584. (d) Tiecco, M.; Testaferri, L.; Santi, C.; Marini, F.; Bagnoli, L.; Temperini, A. Tetrahedron Lett. 1998, 39, 2809. (4) (a) For a review, see: Zefirov, N. S. In Organic Synthesis: Modern Trends, Proceedings of the 6th IUPAC Symposium on Organic Synthesis, Moscow, 1986; Chizhov, O. S., Ed.; Blackwell: Oxford, UK, 1987, p 122. (b) SO 3 + RSCl: Zefirov, N. S.; Kos’min, A. S.; Sorokin, V. D.; Shastin, A. V.; Balenkova, E. S. Dokl. Akad. Nauk SSSR, 1984, 276, 1139. (c) SO3 + Cl2: Zefirov, N. S.; Kos’min, A. S.; Sorokin, V. D.; Zhdankin, V. V. J. Org. Chem. 1984, 49, 4086. (d) SO3 + AcF: Krespan, C. G.; England, D. C. J. Org. Chem. 1975, 40, 2937. Shastin, A. V.; Gavrishova, T. N.; Balenkova, E. S. Zh. Org. Khim. 1985, 21, 1862. Gavrishova, T. N.; Shastin, A. V.; Balenkova, E. S. Zh. Org. Khim. 1991, 27, 673. (e) SO3 + R2NCl: Zefirov, N. S.; Zyk, N. V.; Kolbasenko, S. I.; Kutateladze, A. G. Sulfur Lett. 1984, 2, 95. Zefirov, N. S.; Zyk, N. V.; Kolbasenko, S. I.; Kutateladze, A. G. J. Org. Chem. 1985, 50, 4539. (f) SO3 + XeF2: Brel’, V. K.; Gakh, A. A.; Zhdankin, V. V.; Zefirov, N. S.; Koz’min, A. S.; Korkin, A. A.; Kutateladze T. 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(l) SO3 + R2NSCl: Kutateladze, A. G.; Zyk, N. V.; Denisko, O. V.; Zefirov, N. S. Zh. Org. Khim. 1991, 27, 659. (5) Zefirov, N. S.; Zyk, N. V.; Lapin, Yu. A.; Nesterov, E. E.; Ugrak, B. I. J. Org. Chem. 1995, 60, 6771. 7121 J. Org. Chem. 1999, 64, 7121-7128 10.1021/jo990679t CCC: $18.00 © 1999 American Chemical Society Published on Web 08/31/1999