1996 cycloaddition reactions cycloaddition reactions O 0070 -070Studies on (4 + 3) Cycloadditions of Cyclic Oxyallyls. Part 6. (4 + 3) Cycloadditions of Cyclic Oxyallyls and Cyclic 1,3-Dienes. -The influences of substitution on the cyclohexanone rings along with the variation of bases and solvents on the (4 + 3) cycloaddition of the oxyallyl intermediates derived from cyclohexanones to cyclic 1,3-dienes under Foehlisch conditions (Et3N in CF3CH2OH) are investigated. In comparison with the Foehlisch reaction of (IV) with (IIa), the corresponding Schmid cycloaddition of (VII) affords the cycloadducts ( V) in higher yields with greater diastereoselectivity. The described ( 4 + 3) cycloaddition represents a new route to medium-sized carbocycles and heterocycles, such as (X). -(JIN, S.; CHOI, J.-R.; OH, J.; LEE, D.; CHA, J. K.; J.

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halogen compoundshalogen compounds (acyclic compounds) P 0030 -086A Practical, Stereoselective Synthesis of (E)-and (Z)-2-Bromo-2pentenes.-A short preparation of title compounds (VII) and (III) is described, which is suitable for large-scale production. These bromides may be useful for the synthesis of the corresponding organometallic reagents which are required for synthetic studies towards asteltoxin. - (KIM, H.; LEE, S.-K.; LEE, D.; CHA, J. K.; Synth. Commun. 28 (1998) 4, 729-735; Dep. Chem., Univ. Ala., Tuscaloosa, AL 35487, USA; EN)