Palladium-Catalyzed 1,4-Difunctionalization of Butadiene To Form Skipped Polyenes

Abstract

A palladium-catalyzed 1,4-addition across the commodity chemical 1,3-butadiene to afford skipped polyene products is reported. Through a palladium σ→π→σ allyl isomerization, two new carbon-carbon bonds are formed with high regio- and trans stereochemical selectivity of the newly formed alkene. The utility of this method is highlighted by the successful synthesis of the ripostatin A skipped triene core.

Cooperative Iodide Pd(0)‐Catalysed Coupling of Alkoxyallenes and N‐Tosylhydrazones: A Selective Synthesis of Conjugated and Skipped Dienes

“…[8] More recentlyI r, [9] Ni, [8a, 10] Ti [11] and Cu [12] have also been exploited.E xamples of the enantioselective introduction of as tereogenic centre adjacent to double bonds have been reported. [15] In the same way,t he stereo-defined construction of functionalised conjugated dienes represents am ajor goal in organic synthesis, [4a, 5a, b, 16] andmany efforts have been devoted in the past decades exploiting metal-catalysedc ouplings of alkynes or allenes and suitable alkenes [17] or 1,4 elimination processes. [15] In the same way,t he stereo-defined construction of functionalised conjugated dienes represents am ajor goal in organic synthesis, [4a, 5a, b, 16] andmany efforts have been devoted in the past decades exploiting metal-catalysedc ouplings of alkynes or allenes and suitable alkenes [17] or 1,4 elimination processes.…”

Transition‐Metal‐Catalyzed Three‐Component Difunctionalizations of Alkenes

“…Thus, Sigman et al. described a highly selective 1,4‐difunctionalization of butadiene with alkenyl triflates and aryl(vinyl) boronic acids in 2013 (Scheme ) . Various skipped dienes and trienes were produced in moderate‐to‐good yields with high trans ‐stereoselectivity.…”

A reductive coupling strategy towards ripostatin A

“…While classical methods for the preparation of 1,4-dienes include partial reduction of alkynes and carbonyl olefination, a variety of transition-metal-mediated processes have been developed for the synthesis of skipped dienes of varied substitution patterns [12–15]. Most recently, Sigman and colleagues have reported a palladium-catalyzed 1,4-difunctionalization of 1,4-butadiene with vinylboronic acid and vinyl triflate that can be used to rapidly access the skipped triene of ripostatin A [16]. …”