AbstractKey features of the strategy are NHC‐mediated organocoupling and Grubbs‐catalyzed metathesis reaction.

The enantioselective intramolecular Rauhut-Currier reaction has been developed using a bifunctional dipeptidic phosphane catalyst, providing a direct access to biologically active α-methylene-δ-valerolactones in high yields and enantiomeric excesses. The novel catalyst is accessible in only four steps from commercial sources and exhibits unusual binding selectivities for a small molecule, suggesting the possibility for long-range interactions between the catalyst and the substrate.

NHC-enolate plus 3: N-heterocyclic carbenes (NHCs) serve as organocatalysts for the [2+3] annulation of nitrovinylindoles with α-chloroaldehydes via an intermediate azolium enolate. The method provides trans-disubstituted pyrroloindolones with good yields and excellent diastereo- and enantioselectivities. Further transformations lead to tetracyclic pyrrolo[1,2-a]indoles with potential psychotropic and other bioactivities.

Small-molecule modulators of biological targets play a crucial role in biology and medicine. In this context, diversity-oriented synthesis (DOS) provides strategies toward generating small molecules with a broad range of unique scaffolds, and hence three-dimensionality, to target a broad area of biological space. In this study, an organocatalysis-derived DOS library of macrocycles was synthesized by exploiting the pluripotency of aldehydes. The orthogonal combination of multiple diversity-generating organocatalytic steps with alkene metathesis enabled the synthesis of 51 distinct macrocyclic structures bearing 48 unique scaffolds in only two to four steps without the need for protecting groups. Furthermore, merging organocatalysis and alkene metathesis in a one-pot protocol facilitated the synthesis of drug-like macrocycles with natural-product-like levels of shape diversity in a single step.

AbstractThe NHC‐catalyzed reaction between aromatic/aliphatic aldehydes, nitrosobenzenes, and enals proceeds through an aza‐benzoin‐type transformation and an internal redox esterification to afford hydroxamic esters.

Abstractby a redox esterification of unsaturated aldehydes with oximes

The acid–base organocatalyzed intramolecular Rauhut–Currier (RC) reaction of the dienone enolates has been developed. The enantioselective RC process produces the highly functionalized α-methylidene-γ-butyrolactones as a single diastereomer with up to 98% ee.

A triazolium salt derived N-heterocyclic carbene catalyzes the redox esterification reaction between α-β-unsaturated aldehydes and oximes. The resulting saturated oxime esters were obtained in very good yields for a broad range of aliphatic, aromatic and heteroaromatic substrates.

NHC-Enolate plus 3: NHC-Organokatalyse (NHC=N-heterocyclisches Carben) ermöglicht eine [2+3]-Anellierung von Nitrovinylindolen mit α-Chloraldehyden über ein intermediäres Azolium-Enolat. Die Methode eröffnet einen effizienten Zugang zu trans-disubstituierten Pyrroloindolonen in guten Ausbeuten und mit exzellenten Diastereo- und Enantioselektivitäten. Weitere Transformationen führen zu tetracyclischen Pyrrolo[1,2-a]indolen mit möglichen psychotropen und anderen Bioaktivitäten. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The honey pot: The NHC-catalyzed reaction between nitrosobenzenes, aromatic/aliphatic aldehydes, and enals proceeded through an aza-benzoin-type reaction and an internal redox esterification to afford hydroxamic esters in good yields.

AbstractThe title compounds are obtained from α,β‐unsaturated aldehydes, aromatic phosphorus ylides, and pyrazolones in the presence of prolinol‐derived catalyst PRO via an asymmetric Michael/Wittig/oxa‐Michael reaction sequence.

An efficient one pot asymmetric synthesis of tetrahydropyrano[2,3-c]pyrazoles has been developed. This class of biologically active heterocycles can be obtained via a secondary amine catalyzed asymmetric Michael/Wittig/oxa-Michael reaction sequence. Remarkably, the title compounds were accessible in good to very good yields and very good to excellent enantioselectivities after a single purification step.

AbstractAn atom‐economical, chemo‐, diastereo‐, and enantioselective approach is presented.

Polyfuncionalized cyclopentanones with three contiguous stereogenic centers were formed in good to excellent yields and stereoselectivities by utilizing a secondary amine/N-heterocyclic carbene catalytic system in the reaction of beta-oxo sulfones with unsaturated aldehydes. In addition, the influence of the catalysts on the diastereoselectivity of the final product was studied by H-1 NMR spectroscopy.

AbstractWährend sich die organokatalytischen Dominoreaktionen (auch Organokaskadenkatalysen genannt) im letzten Jahrzehnt zu einem wichtigen Hilfsmittel in der Synthesechemie entwickelt haben, fand die Anwendung von N‐heterocyclischen Carbenen (NHCs) als Katalysatoren in Dominoreaktionen erst in den letzten drei Jahren zunehmend Beachtung. Unter Berücksichtigung der besonderen Aktivierungsmodi der Substrate durch die NHC‐Katalysatoren ist eine Unterscheidung zwischen einer einzelnen chemischen Transformation und einer sequenziellen Eintopfreaktion schwierig. Das Ziel dieses Kurzaufsatzes besteht darin, die Domino‐, Kaskaden‐ und Tandemkatalyse in Gegenwart von NHC‐Katalysatoren kritisch zu betrachten und jüngste Publikationen auf diesem Gebiet vorzustellen.

While organocatalyzed domino reactions or "organocascade catalysis" developed into an important tool in synthetic chemistry during the past decade, the utility of N-heterocyclic carbenes (NHCs) as catalysts in domino reactions has only received growing attention in the past three years. Taking into account the unique activation modes of the substrates by NHC catalysts, it is often difficult to distinguish between a single chemical transformation and a sequential one-pot transformation. Therefore, herein we present a critical consideration of domino, cascade, and tandem catalysis in the case of NHC catalysts and highlight recent publications in this area.

AbstractModerate to good enantioselectivities are observed in the cross‐benzoin reaction of aldehydes (I) with ketones (II) in the presence of a novel triazolium salt as chiral catalyst precursor.

A new triazolium salt derived N-heterocyclic carbene catalyses an asymmetric cross-benzoin-type reaction of heteroaromatic aldehydes and various trifluoromethyl ketones in good to excellent yields (69-96%) and moderate to good enantioselectivities (ee = 39-85%). Up to 99% ee can be achieved by recrystallisation.