A Rational Approach Towards a New Ferrocenyl Pyrrolidine for Stereoselective Enamine Catalysis

Ferrocene (Fc) as a privileged framework for chiral organocatalysts (Orgcat) has been developed rapidly in recent years. Herein, five categories have been summarized, including Fc‐based nucleophilic, bifunctional, Brønsted acid, hydrogen‐bonding organocatalysts and Fc‐based frustrated Lewis pairs. Their applications in enantioselective transformations were also highlighted and discussed in this Minireview.

show abstract

“…In 2013, Cozzi et al. prepared a ferrocenyl pyrrolidine catalyst Fc‐OC‐29 by rational design (Scheme ).…”

Section: Ferrocene‐based Chiral Organocatalystsmentioning

confidence: 99%

“…In 2013, Cozzi [28] et al prepared af errocenyl pyrrolidine catalyst Fc-OC-29 by rational design (Scheme14). In fact, Fc-OC-29 was not regardeda sabifunctional organocatalyst, because it containso nly an activation center and no hydrogen-bonding group within itss tructure.…”

Section: Ferrocene-based Bifunctional Organocatalysts For Michael Reamentioning

confidence: 99%

Ferrocene as a Privileged Framework for Chiral Organocatalysts

Zhu

Cui

et al. 2018

ChemCatChem

View full text Add to dashboard Cite

show abstract

“…The preferred chiral secondary amines are substituted pyrrolidines with a myriad of substituents in the 2‐position. A by no means complete or chronological collection is presented in Scheme for illustration purposes.…”

Section: Introductionmentioning

confidence: 99%

“…The regioselectivity has been discussed in terms of higher stability of the corresponding enamine with a trisubstituted double bond ( Scheme ). Besides the explicit discussions of these remarkable phenomena, a difference in the stability of the enamines is often assumed implicitly when suggesting transition state models in which the enamines adopt an s‐ trans or s‐ cis conformation …”

Section: Introductionmentioning

confidence: 99%

Rigorous Conformational Analysis of Pyrrolidine Enamines with Relevance to Organocatalysis

Husch

Seebàch

Beck

et al. 2017

Helvetica Chimica Acta

View full text Add to dashboard Cite

It has been suggested that the origin of regio-and stereoselectivity in Michael additions of pyrrolidine enamines is achieved by thermodynamic rather than kinetic control through distinct conformational preferences of the enamines. We assess this proposal by elaboration of a computational protocol that warrants sufficient accuracy. The small energy differences between the conformers necessitate a high accuracy of the electronic structure method which, in addition, must allow for computationally feasible calculations of a large number of conformers. Our protocol is based on density functional theory which we validated against explicitly correlated coupled cluster theory. The results are in agreement with the available experimental data, but illustrate that conformational preferences determined for one enamine are not readily transferable to other types of enamines. We found that an appropriate conformational sampling is inevitable to arrive at meaningful conclusions. Most prominently, s-cis and strans conformers are similarly stable for aldehyde-and ketone-derived enamines. The regio-and stereoselectivity in Michael additions of pyrrolidine-derived enamines can not be explained by pronounced stability differences of the enamine isomers and conformers in general, disproving the thermodynamic-control hypothesis. The elucidation of the origin of regio-and stereoselectivity requires further theoretical investigations of the elementary steps of Michael additions.

show abstract

“…Starting from chiral nitro derivatives obtained by nitro‐Michael reactions,49 the corresponding adducts with benzhydrylic alcohols were obtained in quite high diastereoisomeric ratio. In addition, the prepared compounds can be used to access new and interesting pyrrolidine derivatives, which are possible selective and tailored organocatalysts (Scheme ) 50. Unfortunately, this new methodology shows quite severe limitations, particularly concerning the scope of the alcohols that can be utilized.…”

Section: Introductionmentioning

confidence: 99%

From QCA (Quantum Cellular Automata) to Organocatalytic Reactions with Stabilized Carbenium Ions

Gualandi

Mengozzi

Manoni

et al. 2016

The Chemical Record

View full text Add to dashboard Cite

What do quantum cellular automata (QCA), "on water" reactions, and SN 1-type organocatalytic transformations have in common? The link between these distant arguments is the practical access to useful intermediates and key products through the use of stabilized carbenium ions. Over 10 years, starting with a carbenium ion bearing a ferrocenyl group, to the 1,3-benzodithiolylium carbenium ion, our group has exploited the use of these intermediates in useful and practical synthetic transformations. In particular, we have applied the use of carbenium ions to stereoselective organocatalytic alkylation reactions, showing a possible solution for the "holy grail of organocatalysis". Examples of the use of these quite stabilized intermediates are now also considered in organometallic chemistry. On the other hand, the stable carbenium ions are also applied to tailored molecules adapted to quantum cellular automata, a new possible paradigm for computation. Carbenium ions are not a problem, they can be a/the solution!

show abstract

A Rational Approach Towards a New Ferrocenyl Pyrrolidine for Stereoselective Enamine Catalysis

Cited by 23 publications

References 70 publications

Ferrocene as a Privileged Framework for Chiral Organocatalysts

Ferrocene as a Privileged Framework for Chiral Organocatalysts

Rigorous Conformational Analysis of Pyrrolidine Enamines with Relevance to Organocatalysis

From QCA (Quantum Cellular Automata) to Organocatalytic Reactions with Stabilized Carbenium Ions

Contact Info

Product

Resources

About