- Metal-catalyzed cycloisomerization of enyne functionalities via a 1,3-alkylidene migration
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We report a new metal-catalyzed 6-endo-dig cyclization of cis-4,6-dien-1-yn-3-ols, which produces substituted benzene and naphthalene derivatives with structural reorganization. In this process, we observe a 1,3-alkylidene migration via cleavage of the olefin double bond of the starting substrates. The ease and reliability of this cyclization are manifested by its compatibility with a wide array of diverse substrates and several π-alkyne activators, including PtCl2, Zn(OTf)2, AuCl, and AuCl3. Copyright
- Lin, Ming-Yuan,Das, Arindam,Liu, Rai-Shung
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p. 9340 - 9341
(2007/10/03)
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- The role of oxygen acidity on the side-chain fragmentation of ring methoxylated benzocycloalkenol radical cations
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The reactivity of 2,2-dimethyl-5-methoxyindan-1-ol (1) and 2,2-dimethyl-6-methoxytetral-1-ol (2) radical cations has been studied both in acidic and basic solution. At pH≤4 both 1.+ and 2.+ undergo Cα-H deprotonation as the exclusive reaction with k=4.6×104 and 3.2×104 s-1, respectively. In basic solution 1.+ and 2.+ behave as oxygen acids undergoing -OH-induced α-OH deprotonation in a diffusion controlled process (k-OH≈1010 M-1 s-1). An intermediate alkoxyl radical is formed which undergoes a 1,2-hydrogen atom shift in competition with C-C β-scission (with 1.+) or as the exclusive pathway (with 2.+). A behavior which is interpreted in terms of the greater ease of ring-opening of a five membered ring as compared to a six-membered one.
- Bellanova, Monica,Bietti, Massimo,Salamone, Michela
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p. 6401 - 6404
(2007/10/03)
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