Pd(0)-catalyzed carbonylation of (Z)-2-en-4-yn carbonates in the presence of a balloon pressure of CO in an alcohol donates vinylallenyl esters with an exclusively E-configuration and in high yields. The fact that no such reactivity could be observed with E-configured enyne carbonates may indicate that the reaction is promoted via the cooperative coordination of palladium with both alkynyl and carbonate moieties. Supporting Information Available. Detailed experimental procedures, and compound characterization data. This material is available free of charge via the Internet at http://pubs.acs.org.

Rhodium-and Palladium-Catalyzed 1,5-Substitution Reactions of 2-En-4-yne Acetates and Carbonates with Organoboronic Acids. -The reaction of (E)-and (Z)-enyne carbonates and (Z)-enyne acetates allows convenient access to (E)-configurated vinylallenes. Starting from (E)-enyne acetates, however, vinylallenes are not available. The reaction of optically active enynes proceeds with racemization. -(UECUENCUE, M.; KARAKUS, E.; KUS, M.; AKPINAR, G. E.; AKSIN-ARTOK, O.; KRAUSE, N.; KARACA, S.; ELMACI, N.; ARTOK*, L.; J. Org. Chem. 76 (2011) 15, 5959-5971, http://dx.doi.org/10.1021/jo200201r ; Dep. Chem., Fac. Sci., Izmir Inst. Technol., Urla, TR-35437 Izmir, Turk.; Eng.) -Jannicke

Regio-and Stereoselective Synthesis of 2,3,5-Trienoates by Palladium-Catalyzed Alkoxycarbonylation of Conjugated Enyne Carbonates. -The reaction is performed with various (E)-configurated substrates in the presence of MeOH under balloon pressure of CO. The results become complex with an (E/Z) mixture (bulky -tBu at the double bond), a terminal primary alcohol or a phenyl group at the allylic position. Studies of optically active substrates reveal that the stereochemical outcome [cf. (IVa)] depends on the olefin geometry. A detailed investigation of the reaction mechanism is presented. -(KARAGOEZ, E. S.; KUS, M.; AKPINAR, G. E.; ARTOK*, L.; J. Org. Chem. 79 (2014) 19, 9222-9230, http://dx.doi.org/10.1021/jo5014993 ; Dep. Chem., Fac. Sci., Izmir Inst. Technol., Urla, TR-35437 Izmir, Turk.; Eng.) -Lehmann 15-067