The Lewis (or Brønsted) acid‐catalyzed reaction of 2‐aryl‐N‐sulfonyl aziridines with ferrocene and ruthenocene provided new amino‐functionalized metallocene derivatives arising from a regioselective ring opening of the aziridine. The functionalized metallocene derivatives available by this methodology are suitable precursors for the stereoselective synthesis of metallocene analogues of the relevant tetrahydroisoquinoline motif by a Pictet‐Spengler type reaction. These isoquinoline analogues are also accessible by a TfOH‐catalyzed three‐component reaction of 2‐aryl‐N‐sulfonyl aziridines, ferrocene (or ruthenocene) and formaldehyde.
We report the gold-catalyzed reaction
of vinyldiazo compounds and
alkenylsilanes to produce skipped dienes, which are common structural
motifs in an array of bioactive compounds. This carbon–carbon
bond-forming transformation proceeds with complete regio- and stereoselectivity
with the silyl group serving as a regio- and stereocontrolling element.
Likewise, the use of alkynylsilanes as reaction partners yielded skipped
enynes resulting from a C(sp)–C(sp
3
) coupling. Mechanistic
experiments and DFT studies have provided support for a stepwise mechanism.
We report the regioselective synthesis of silyl-substituted
cyclopentadienyl
esters through gold-catalyzed migratory cycloisomerization of silyl-substituted
vinylallenes. This transformation is proposed to proceed through a
perfectly orchestrated sequence of events including Nazarov-like cyclization
and several silyl and hydrogen rearrangements. Furthermore, exploiting
the multifaceted nature of the gold catalyst, we have also identified
suitable conditions for the synthesis of these cyclopentadienes in
a more straightforward manner through gold-catalyzed reaction of propargyl
esters and alkynylsilanes.
The marriage of heterocyclic compounds with ferrocene has proven to be an extremely fruitful field of research. In fact, in the last years, several ferrocene-embedded heterocyclic compounds have been reported. In some cases, the synergistic combination of the properties of the heterocyclic and metal-lacyclic motifs provides to the fused systems interesting applications. This Review summarizes the major advances in the synthesis of ferrocene-fused nitrogen heterocyclic compounds and their applications, particularly in asymmetric catalysis.
The Front Cover shows the fusion of ferrocene and heterocyclic compounds (exemplified by pyridine). The chemistry of ferrocene‐fused nitrogen heterocycles has recently become an exciting field of research. From a synthetic point of view, the transfer to ferrocene of some of the powerful transition‐metal‐catalyzed methodologies developed for the C−H bond functionalization of benzene derivatives has no doubt contributed to this extraordinary development. Moreover, because of the planar chirality most of these ferrocene‐fused systems exhibit, some of them have found interesting applications as organocatalysts in asymmetric catalysis. In this review, we showcase recent advances in the synthesis and applications of this type of fused systems. The cover was designed by Illan López. More information can be found in the Review by L. A. López and co‐workers.
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