(1‐Alkynyl)dicarbonylcyclopentadienyliron Complexes as Electron‐Rich Alkynes in Organic Synthesis: BF₃‐Mediated [2+2] Cycloaddition/Ring‐Opening Providing (2‐Alkenyl‐1‐imino)iron Complexes

Abstract

Strike while the iron is hot! A BF3‐mediated formal [2+2] cycloaddition between (1‐alkynyl)iron complexes and aromatic aldehyde imines occurs, which is followed by ring‐opening of the initially formed azacyclobutenes to yield (2‐alkenyl‐1‐imino)iron complexes (see scheme). The resulting iron complexes undergo deferric substitution reactions with water under oxidative conditions to afford the corresponding cinnamamides with high E selectivity.

Rhenium-Catalyzed Regio- and Stereoselective Addition of Imines to Terminal Alkynes Leading to N-Alkylideneallylamines

“…On the other hand, electrophiles can also add to the alkynyl β-carbon to give vinylidene metal complexes . Yorimitsu and Oshima et al proposed that the reaction mechanism involved a β-addition step in the stoichiometric [2 + 2]cycloaddition/ring opening of the alkynyliron complexes to imines to give α,β-unsaturated iminoiron complexes mediated by BF 3 ·OEt 2 . , We disclose herein the rhenium-catalyzed reaction of terminal alkynes with imines to give N -alkylideneallylamine derivatives. Allylamines are useful building blocks for the synthesis of a variety of nitrogen-containing organic molecules .…”

Einfluss der Nachbehandlung auf das Karbonatisierungsverhalten von Beton aus klinkerarmen Zementen

“…There are almost no reports in the literature on the [2+2] cycloaddition reaction of terminal alkynes and imines via in situ generation of allene type intermediates. As a rare example, Yorimitsu, Oshima and co‐workers illustrated the thermal [2+2] cycloaddition reaction of the electron‐rich dicarbonylcyclopentadienyl(phenylethynyl)iron [Fp(CCR)] with aromatic aldimines in the presence of BF 3 ⋅OEt 2 as Lewis acid, leading to azacyclobutenes, which undergo ring opening to afford (2‐alkenyl‐1‐imino)iron complexes 5…”

Catalyzed M–C coupling reactions in the synthesis of σ-(pyridylethynyl)dicarbonylcyclopentadienyliron complexes

“…Metal s-alkynyl complexes displaying such peculiar characteristics as linear geometry, high stability, and p-unsaturated character have been demonstrated to constitute promising building blocks for the design of materials, which can possess such properties as optical nonlinearity, [1][2][3][4][5] light-emission, [6][7][8][9][10][11][12] and electrical conductivity. [13][14][15][16][17][18] Moreover, they are an important class of coordination compounds because of their relevance in synthetic chemistry [19][20][21][22][23][24] and proton reduction catalysis. [25][26][27] A variety of methods for the synthesis of transition metal acetylides have been developed.…”