Triene electrocyclizations: Some structure reactivity relations |
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Authors: | EN Marvell G Caple C Delphey J Platt N Polston J Tashiro |
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Institution: | Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 USA |
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Abstract: | Two stereoselective routes for the synthesis of trienes having a central cis double bond have been devised. These were employed for the synthesis of (Z)-1-(cyclohexen-1-yl)-1,3-butadiene (1), (Z,E)-1-(cyclohexen-1-yl)-1,3-pentadiene (2), (Z,Z)-1-(cyclohexen-1-yl)-1,3-pentadiene (3), 1,2-divinyleyclohexene (4), (E,Z)-1-phenyl-1,3,5-hexatriene (5), (Z,Z)-1-phenyl-1,3,5-hexatriene (6) and (E,Z)-1-(p-chlorophenyl)-1,3,5-hexatriene (7). Rates of the thermal electrocyclization and activation parameters were measured for these in inert solvents. The results are tabulated below. Compound | k1 x 105 | (sec?1) | Temp (°C) | ΔH3 | ΔS3 | 1 | 12·8 | 132 | 29 | ?6 | | 2 | 12·5 | 132 | 29 | ?1 | | 3 | 2·6 | 173 | 34 | ?5 | | 4 | 3·86 | 125 | 25 | ?15 | | 5 | 16·0 | 145 | 28 | ?8 | | 6 | 3·0 | 195 | | | | 7 | 15·0 | 145 | 25 | ?18(?) | |
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