A series of nitrogen-tethered allenynes (‘5-aza-1,2-dien-7-ynes’) 1 were transformed to the corresponding 3-acyl-4-alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl2 in MeOH at 70°. Initial Pt-promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2, the intermediate is intercepted
The reaction of allenynes with N2CHSiMe3 in the presence of RuCl(cod)Cp* catalyst at room temperature constitutes a selective, general route to alkylidenebicyclo[3.1.0]hexanes having an adjacent Z-CH=CHSiMe3 group. The reaction shows that the RuCl(Cp*) moiety favours reductive elimination of a metallacyclobutane intermediate and not the enyne metathesis process.
Gold-Catalyzed <i>N</i>,<i>O</i>-Functionalizations of 6-Allenyl-1-ynes with <i>N</i>-Hydroxyanilines To Construct Benzo[<i>b</i>]-azepin-4-one Cores
作者:Antony Sekar Kulandai Raj、Balaji S. Kale、Bhanudas Dattatray Mokar、Rai-Shung Liu
DOI:10.1021/acs.orglett.7b02629
日期:2017.10.6
Gold-catalyzedreactions of 6-allen-1-ynes with N-hydroxyanilines afford thermally stable benzoazepin-4-ones in anti-selectivity; these anti-configured products are easily isomerized to their syn-isomers on a silica column. The mechanism of reactions likely involve initial nitrone/allene cycloadditions, followed by skeletal rearrangement of resulting intermediates.
A ring-closing metathesis reaction of allenynes occurred at room temperature in the presence of a molybdenum alkylidene complex to give ring-closed vinylallenes. The vinylallene skeletons were constructed by a metathesis-type reaction between the alkyne moiety and the proximal carbon-carbon double bond of the allene moiety.
Mercury(II) Triflate-Catalyzed Cycloisomerization of Allenynes to Allenenes
[Graphics]Cycloisomerizations of allenynes to allenenes have been studied in the presence of catalytic amounts of [Hg(OTf)(2)] in acetonitrile. The catalytic system is quite effective for terminal 1,6-allenynes: allenenes were obtained in reasonable to high yields. However, treatment of allenynes with disubstituents at the allenic terminal carbon yielded a triene and/ or allenene as a major product(s) depending upon the substituents.