Spectral effects in cyclobutane derivatives : The bathochromic-hypochromic shifts in compounds related to verbenone |
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Authors: | Amatzya Y Meyer Reuven Pasternak Jeffrey Sterling Naftali Lander Raphael Mechoulam |
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Institution: | Department of Organic Chemistry, Hebrew University, Jerusalem, Israelag];Department of Natural Products, School of Pharmacy, Hebrew University, Jerusalem, Israel |
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Abstract: | The bathochromic-hypochromic spectral shifts, observed in bicyclic enones that contain a 4- or a 3-membered ring, are discussed in molecular-mechanical and molecular-orbital terms. It is proposed that the effect, not only by the cyclopropane but also by the cyclobutane ring, is due to extension of the CCCO chromophore, and not to its mere distortion from “normal” geometry. The high-energy absorption of umbellulone (3), 220 nm in ethanol, is characterized as a second π-π*. 2-Methylbicyclo3.2.1]oct-2-en-4-one (7) has been synthesized, and its preparation and spectrum are described. |
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