The diethylphosphonate substituent is freeradical stabilizing by a conjugation mechanism as judged by its effect on the rate of the methylenecyclopropane rearrangement.
通过其对亚甲基环丙烷重排速率的影响判断的共轭机制,二乙基膦酸酯取代基是自由基稳定的。
A New Highly Efficient Three-Component Domino Heck–Diels–Alder Reaction with Bicyclopropylidene: Rapid Access to Spiro[2.5]oct-4-ene Derivatives Part 77 in the series “Cyclopropyl Building Blocks in Organic Synthesis”. For Part 76 see: S. Wiedemann, I. Marek, A. de Meijere, Synlett 2002, submitted. Part 75: M. W. Nötzel, K. Rauch, T. Labahn, A. de Meijere, Org. Lett. 2002, 4, 839–841.
作者:Hanno Nüske、Stefan Bräse、Sergei I. Kozhushkov、Mathias Noltemeyer、Mazen Es-Sayed、Armin de Meijere
three-component reaction with a variety of dienophiles to furnish the dominoHeck-Diels-Alder products 18 regioselectively in most cases in good to very high yields (49-100 %). The reaction of 1 with iodobenzene (2-Ph) and 17 a gave 18 a-Ph in virtually quantitative yield-also on a gram scale-using only 1 mol % of catalyst, and even bromobenzene (22) gave 18 a-Ph in 59 % yield. Bicyclopropylidene (1), in the
5-Alkylidene-hexahydro-1H-cyclopenta[c]pyrrol-1,3-diones by nickel(0) or palladium(0) catalyzed [3+2] cycloaddition of methylenecyclopropanes with maleimides
作者:Paul Binger、Andreas Freund、Petra Wedemann
DOI:10.1016/s0040-4020(01)80117-4
日期:1989.1
Nickel(0) catalyzed [3+2] cycloaddition of methylenecyclopropanes 1a - e with N-substituted maleimide 3b (R = CH3) and 3c (R = Ph) leads almost exclusively to the title compounds 6 and 7. The same reaction occurs in the presence of a palladium(0) catalyst with lower selectivity. Neither unsubstituted maleimide (3a) nor maleic anhydride (2a) undergo this metal catalyzed cycloaddition. With isopropylidenecyclopropane