Abstract Asymmetric catalysis is an advanced area of chemical synthesis, but the handling abundantly available, purely aliphatic hydrocarbons has proven to be challenging. Typically, heteroatoms or aromatic substructures are required in substrates and reagents facilitate efficient interaction with chiral catalyst. Confined acids have recently been introduced as tools for homogenous asymmetric catalysis, specifically enable processing small unbiased 1 . However, reactions which both substrate...

The chiral phosphoric acid TRIP, a useful Brønsted catalyst, easily becomes contaminated with metal impurities in the form of phosphate salts during synthesis. This significantly reduces content free product which can hamper catalytic activity. Methods to judge whether TRIP contains mainly or are presented, using ¹H NMR spectroscopy simple pH test. An improved synthetic protocol for was established that reliably produces acid.

Aldol cyclodehydration of 4-substituted-2,6-heptanediones leads to enantiomerically enriched 5-substituted-3-methyl-2-cyclohexene-1-ones, which serve as perfume ingredients and valuable synthetic building blocks. Primary amines derived from cinchona alkaloids in combination with acetic acid are efficient catalysts for this transformation, deliver both enantiomers the celery ketone. Supporting information article is available on WWW under...

Branching out: An organocatalytic reductive amination of α-branched ketones using dynamic kinetic resolution is reported. The cis-2-substituted cyclohexyl amines were obtained in high diastereoselectivity and enantioselectivity from the corresponding ketones. Detailed facts importance to specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please note: publisher responsible for...

Abstract Herein we describe the development of a catalytic enantioselective alkynylogous Mukaiyama aldol reaction. The reaction is catalyzed by newly designed chiral disulfonimide and delivers allenoates in high yields with excellent regio‐, diastereo‐, enantioselectivity. Our process tolerates broad range aldehydes combination diverse alkynyl‐substituted ketene acetals. products can be readily derivatized to furnish variety highly substituted enantiomerically enriched building blocks.

Abstract A chiral disulfonimide (DSI)‐catalyzed asymmetric reduction of N ‐alkyl imines with Hantzsch esters as a hydrogen source in the presence Boc 2 O has been developed. The reaction delivers Boc‐protected amines excellent yields and enantioselectivity. method tolerates large variety alkyl amines, thus illustrating potential for general reductive cross‐coupling ketones diverse it was applied synthesis pharmaceuticals ( S )‐Rivastigmine, NPS R‐568 Hydrochloride, R )‐Fendiline.

Reactions that form a product with the same reactive functionality as of one starting compounds frequently end in oligomerization. As salient example, selective aldol coupling smallest, though arguably most useful, enolizable aldehyde, acetaldehyde, just partner substrate has proven to be extremely challenging. Here, we report highly enantioselective Mukaiyama reaction simple triethylsilyl (TES) and tert-butyldimethylsilyl (TBS) enolates acetaldehyde various aliphatic aromatic acceptor...

Abstract An asymmetric Torgov cyclization, catalyzed by a novel, highly Brønsted acidic dinitro‐substituted disulfonimide, is described. The reaction delivers the diene and various analogues with excellent yields enantioselectivity. This method was applied in very short synthesis of (+)‐estrone.

Abstract Herein we describe the development of a catalytic enantioselective alkynylogous Mukaiyama aldol reaction. The reaction is catalyzed by newly designed chiral disulfonimide and delivers allenoates in high yields with excellent regio‐, diastereo‐, enantioselectivity. Our process tolerates broad range aldehydes combination diverse alkynyl‐substituted ketene acetals. products can be readily derivatized to furnish variety highly substituted enantiomerically enriched building blocks.

Abstract A two‐step procedure for producing optically active, high value primary amines has been developed. The first and key step is the asymmetric reductive amination of a prochiral alkyl (acyclic or cyclic) aryl ketone with ( R )‐ S )‐α‐methylbenzylamine (α‐MBA). normally stepwise excessive procedures chiral auxiliary approaches are avoided by simultaneously incorporating new stereogenic center at former carbonyl carbon during one. Specifically, one hydrogenation (4–8 bar) substrate in...

Abstract A highly diastereoselective and enantioselective Brønsted acid catalyzed reductive condensation of N−H imines was developed. This reaction is by a chiral disulfonimide (DSI), uses Hantzsch esters as hydrogen source, delivers useful C 2 ‐symmetric secondary amines.

Die Aldol-Cyclodehydratisierung von 4-substituierten 2,6-Heptandionen führt zu enantiomerenangereicherten 5-substituierten 3-Methyl-2-cyclohexen-1-onen, die in Parfümen und als Synthesebausteine Anwendung finden. Von Cinchona-Alkaloiden abgeleitete primäre Amine erwiesen sich Kombination mit Essigsäure effiziente Katalysatoren (siehe Schema).

Maßgebliche Substituenten: Die Titelreaktion nutzt die dynamische kinetische Racematspaltung und liefert so cis-2-substituierte Cyclohexylamine mit hohen Diastereo- Enantioselektivitäten.

Abstract Polyene cyclizations are among the most complex and challenging transformations in biology. In a single reaction step, multiple carbon–carbon bonds, ring systems stereogenic centres constituted from simple, acyclic precursors 1–3 . Simultaneously achieving this kind of precise control over product distribution stereochemistry poses formidable task for chemists. particular, polyene cyclization (3 E ,7 )-homofarnesol to valuable naturally occurring ambergris odorant (−)-ambrox is...

Lakritze oder Sellerie der Katalysator entscheidet! Die beiden Sellerieketon-Enantiomere unterscheiden sich geruchlich stark und sind doch aus demselben symmetrischen Diketon durch eine organokatalytische Aldolreaktion zugänglich. enantiogruppenselektive intramolekulare Aldolisierung von 4-Propylheptan-2,6-dion liefert entweder das nach riechende S-Enantiomer intensivere R-Enantiomer, den Sellerie-Duft des Racemats bestimmt. Details die Zuschrift B. List et al. auf S. 7768 ff.

Even though chemists have long underappreciated the role of London dispersion in catalysis, its importance determining a reaction course is now well recognized. Dispersion interactions been shown to stabilize transition states and govern stereoselectivity. In this context, transfer hydrogenation α,β-unsaturated aldehydes reported by our group via asymmetric counteranion-directed catalysis (ACDC) was revisited mechanistically. Previously, use an engineered Hantzsch ester featuring isopropyl...

Abstract Eine durch ein chirales Disulfonimid (DSI) katalysierte asymmetrische Reduktion von N ‐Alkyliminen mit Hantzsch‐Estern als Wasserstoffquelle in Gegenwart Boc 2 O wurde entwickelt. Diese Reaktion liefert Boc‐geschützte ‐Alkylamine ausgezeichneten Ausbeuten und Enantioselektivitäten. Die Methode toleriert viele verschiedene Alkylamine, was die Möglichkeit einer allgemeinen reduktiven Kreuzkupplung Ketonen verschiedenen Aminen aufzeigt, der Synthese Wirkstoffe ( S )‐Rivastigmin,...

Reductive amination of prochiral unhindered 2-alkanones 1 with (R)- or (S)-alpha-MBA in the presence Yb(OAc)3 (50-110 mol %), Raney-Ni, and hydrogen (120 psi) results increased diastereoselectivity for amine products 2 (80-89% de) good yield (80-87%). The de is based on comparison best previously reported de's when using (S)-alpha-MBA, regardless strategy employed [stepwise (isolation ketimines) one-pot (reductive amination)], reducing agent examined, achiral Lewis acid Brønsted examined. An...

Abstract Macrocyclic natural products (NPs) and analogues thereof often show high affinity, selectivity, metabolic stability, methods for the synthesis of NP‐like macrocycle collections are major current interest. We report an efficient solid‐phase/cyclorelease method a collection macrocyclic depsipeptides with bipartite peptide/polyketide structure inspired by very potent F‐actin stabilizing jasplakinolide/geodiamolide class. The includes assembly acyclic precursor chain on polymeric...

[reaction: see text] A new method for the one-pot asymmetric reductive amination of prochiral aliphatic ketones has been developed. The previously unexplored reagent combination Ti(O(i)Pr)(4)/Raney Ni/H(2) in presence (R)- or (S)-alpha-methylbenzylamine provides good to excellent yield (76-90%) and diastereomeric excess (72-98%). second step, hydrogenolysis, corresponding primary amine high (88-93%) with uncompromised enantiomeric excess.

Natürlich synthetisch: Der Säure/Base-Katalysator (S)-1 katalysiert die hochenantioselektive alkoholytische Desymmetrisierung von meso-Anhydriden. Zum Beispiel ergab Methanolyse des Cyclobutananhydrids 2 in 99:1 e.r. den Halbester 3, der als Schlüsselintermediat einer kurzen enantioselektiven Synthese (+)-Grandisol eingesetzt wurde. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They...

Abstract Eine asymmetrische Torgov‐Cyclisierung wurde entwickelt, die durch ein neuartiges, stark Brønsted‐acides Dinitrodisulfonimid katalysiert wird. Die Reaktion liefert das Torgov‐Dien und diverse Analoga in ausgezeichneten Ausbeuten mit exzellenten Enantioselektivitäten einer sehr kurzen Synthese von (+)‐Estron angewendet.

While imines are frequently used substrates in asymmetric Brønsted acid catalysis, their corresponding salts generally considered unsuitable reaction partners. Such processes challenging because they require the successful competition of a catalytic amount chiral anion with stoichiometric an achiral one. We now show that enantiopure disulfonimides enable reduction N–H imine hydrochloride using Hantzsch esters as hydrogen source. Our scalable delivers crystalline primary amine great...

Abstract A one‐pot asymmetric sequential amination‐alkylation method has been developed for the synthesis of alkyl‐alkyl′ α‐chiral primary amines (aliphatic with a chiral center adjacent to nitrogen atom) from aldehydes. In situ aldimine formation non‐branched, α‐branched, and β‐branched aliphatic aldehydes ( R )‐ or S )‐α‐(methylbenzyl)amine [catalyzed by 5 mol‐% Ti(O i Pr) 4 ] followed reaction methyl, ethyl, n ‐butyl cuprate complex in presence boron trifluoride an allyl Grignard reagent...

We report the use of benzylamine as amine component in Hantzsch ester mediated and chiral Brønsted acid catalyzed enantioselective reductive aminations ketones. The method is noteworthy because benzyl group easily removable, product purification achieved through oxidation removal via basic hydrolysis.