Palladium‐Catalyzed Carbocyclization of Allene—Diene Derivatives. Exploring Different Nucleophiles.

Abstract

Ring closure reactions Ring closure reactions O 0130Palladium-Catalyzed Carbocyclization of Allene-Diene Derivatives. Exploring Different Nucleophiles. -An improved method for the palladium-catalyzed nucleophilic substitution-intramolecular carbocyclization of allene-diene derivatives (I) and (V) is presented. The reactions can be performed in organic solvents like dichloromethane or acetone which allows for reduction of the amount of nucleophile to 10 equivalents and broadens the range of nucleophiles applicable. Interestingly, carbocyclization of allenylcycloheptadiene (V) proceeds with exclusive trans-selectivity, while the corresponding allenylcyclohexadiene (I) cyclizes with absolute cis-selectivity. The ratio of 1,2-to 1,4-addition products in the reaction of cycloheptadiene derivative (V) strongly depends on the nature of nucleophile. -(LOEFSTEDT, J.; NAERHI, K.; DORANGE, I.; BAECKVALL*, J.-E.; J. Org. Chem. 68 (2003) 19, 7243-7248; Dep. Org. Chem., Arrhenius Lab., Univ. Stockholm, S-106 91 Stockholm, Swed.; Eng.) -Mischke 07-048 2004 Ring closure reactions