Enantioselective Alkylation Of Aldehydes Research Articles

Enantioselective Alkylation of Aldehydes with Organoborons Enabled by Nickel/N‐Heterocyclic Carbene Catalysis†

Comprehensive SummaryTransition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility.

ChemInform Abstract: 2‐Pyridylsulfinamides as Effective Catalysts in the Asymmetric Alkylation of Aldehydes with Diethylzinc.

AbstractThe enantioselective alkylation of aldehydes with diethylzinc is achieved in the presence of a chiral sulfinamide as optimal catalyst.

ChemInform Abstract: Enantioselective Alkylation of Aldehydes Using Functionalized Alkylboron Reagents Catalyzed by a Chiral Titanium Complex.

AbstractAn octahydro‐BINOL derived titanium complex is used to catalyze the addition reaction of alkylboron reagents, generated in situ from terminal olefin precursors by hydroboration, to aldehydes to provide secondary alcohols with high enantioselectivities.

Enantioselective Alkylation of Aldehydes with Zinc–2-Pyridylsulfinamides

Enantioselective Alkylation of Aldehydes with Zinc–2-Pyridylsulfinamides

ChemInform Abstract: Enantioselective Alkylation of Aldehydes Using Dialkylzincs Catalyzed by Simple Chiral Diols Derived from Naturally Occurring Monosaccharides.

Abstract Enantioselective alkylation of aldehydes was achieved in up to 84% ee using dialkylzincs catalyzed by simple diols derived from naturally occurring monosaccharides.

ChemInform Abstract: Catalytic Enantioselective Alkylation of Aldehydes by Using Organozinc Halide Reagents.

Functionalized alkylzinc halides can be employed in the enantioselective addition to aldehydes by using a titanium(IV) catalyst derived from a H(8)-binaphthol derivative in the presence of [Ti(OiPr)(4)] and MgBr(2). A range of functionalities, including olefin, chlorine atoms, protected alcohols, amides, and cyano groups, are tolerated in the present reaction, providing the corresponding functionalized alcohols in high yields and enantioselectivities (see scheme).

Titanium-Magnesium-Mediated Enantioselective Alkylation of Aldehydes

Titanium-Magnesium-Mediated Enantioselective Alkylation of Aldehydes

ChemInform Abstract: Enantioselective Addition of Dialkylzincs to Aldehydes Catalyzed by (—)‐MITH.

An effective catalytic system that imparts high enantioselectivity has been disclosed for the synthesis of optically active alcohols, which may undergo further chemical transformations. The enantioselective alkylation of aldehydes with dialkylzincs to afford the corresponding optically active alcohols with excellent enantioselectvities has been achieved in the presence of 0.1-0.5 mol % of the camphor-derived chiral ligand (-)-2-exo-morpholinoisobornane-10-thiol (MITH) (1) at room temperature or at 0 °C.

Enantioselective alkylation of aldehydes using dialkylzincs catalyzed by simple chiral diols derived from naturally occurring monosaccharides

Enantioselective alkylation of aldehydes was achieved in up to 84% ee using dialkylzincs catalyzed by simple diols derived from naturally occurring monosaccharides.

Enantioselective Addition of Dialkylzincs to Aldehydes Catalyzed by (−)‐MITH

An effective catalytic system that imparts high enantioselectivity has been disclosed for the synthesis of optically active alcohols, which may undergo further chemical transformations. The enantioselective alkylation of aldehydes with dialkylzincs to afford the corresponding optically active alcohols with excellent enantioselectvities has been achieved in the presence of 0.1-0.5 mol % of the camphor-derived chiral ligand (-)-2-exo-morpholinoisobornane-10-thiol (MITH) (1) at room temperature or at 0 °C.

Simple Preparation of β-Amino Alcohols Possessing a tert-Butyl Group at the α-Carbon

Simple preparation of β-amino alcohols possessing a tert -butyl group at the α-carbon was achieved. These β-amino alcohols proved to work effectively as catalysts in the enantioselective alkylation of aldehydes.

ChemInform Abstract: Catalytic Highly Enantioselective Alkylation of Aldehydes with Deactivated Grignard Reagents and Synthesis of Bioactive Intermediate Secondary Arylpropanols.

Because of the high reactivity of Grignard reagents, a direct, highly enantioselective Grignard reaction with aldehydes has rarely been disclosed. In this report, Grignard reagents were introduced with bis[2-(N,N′-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity; thus, a highly enantioselective alkylation of aldehydes with Grignard reagents resulted from catalysis by (S)-BINOL-Ti(OiPr)2. It is thought that BDMAEE chelates the in situ generated salts MgBr2 from a Schlenk equilibrium of RMgBr and Mg(OiPr)Br from transmetalation of RMgBr with Ti(OiPr)4. The Mg salts can actively promote the undesired background reaction to give the racemate. The chelation definitely inhibits the catalytic activity of the Mg salts, suppresses the unwanted background reaction, and enables the highly enantioselective addition catalyzed by (S)-BINOL-Ti(OiPr)2. Consequently, the Mg salt byproducts were not removed, less Ti(OiPr)4 than RMgBr was used, and extremely low temperature was avoided in this ...

ChemInform Abstract: Enantioselective Addition of Organometallic Reagents to Carbonyl Compounds: Chirality Transfer, Multiplication and Amplification

Nucleophilic addition of organometallic reagents to carbonyl substrates constitutes one of the most fundamental operations in organic synthesis. Modification of the organometallic compounds by chiral, nonracemic auxiliaries offers a general opportunity to create optically active alcohols, and the catalytic version in particular provides maximum synthetic efficiency. The use of organozinc chemistry, unlike conventional organolithium or -magnesium chemistry, has realized an ideal catalytic enantioselective alkylation of aldehydes leading to a diverse array of secondary alcohols of high optical purity. A combination of dialkylzinc compounds and certain sterically constrained β-dialkylamino alcohols, such as (–)-3-exo-dimethylaminoiso- borneol [(–)-DAIB], as chiral inducers affords the best result (up to 99% ee). The alkyl transfer reaction occurs via a dinuclear Zn complex containing a chiral amino alkoxide, an aldehyde ligand, and three alkyl groups. The chiral multiplication method exhibits enormous chiral amplification: a high level of enantioselection (up to 98%) is attainable by use of DAIB in 14% ee. This unusual nonlinear effect is a result of a marked difference in chemical properties of the diastereomeric (homochiral and heterochiral) dinuclear complexes formed from the dialkylzinc and the DAIB auxiliary. This phenomenon may be the beginning of a new generation of enantioselective organic reactions.

ChemInform Abstract: Catalytic Asymmetric Synthesis of Optically Active Secondary Alcohols Deuterated on the Secondary Carbon by the Enantioselective Alkylation of Aldehydes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Chiral Sulfamide–Amine Alcohol Ligands for Enantioselective Alkylation of Aldehydes

A series of chiral sulfamide–amine alcohols (SAA) (1–6) has been easily synthesized from commercially available chiral amino alcohols. In the absence of Ti(O i Pr)4, ligand 4 catalyzed the asymmetric addition of diethylzinc to aromatic aldehydes with moderate to good yields and enantioselectivities.

Enantioselective Alkylation of Aldehydes with Fluorous TADDOL Analogue

Enantioselective Alkylation of Aldehydes with Fluorous TADDOL Analogue

Enantioselective Alkylation of Aldehydes with Chiral Organomagnesium Amides (COMAs).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Enantioselective alkylation of aldehydes with chiral organomagnesium amides (COMAs).

[reaction: see text] Dialkylmagnesiums react with chiral secondary amines to form chiral organomagnesium amides (COMAs). These reagents alkylate aldehydes to form secondary alcohols with enantioselectivities up to 91:9 er.

ChemInform Abstract: Enantioselective Alkylation of Aldehydes with Diethylzinc Using a New Catalyst System, ((R)‐Thiolan‐2‐yl)diphenylmethanol and Metal Alkoxides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Enantioselective Alkylation of Aldehydes with Diethylzinc Using a New Catalyst System, ((R)-Thiolan-2-yl)diphenylmethanol and Metal Alkoxides

Abstract Various optically active secondary alcohols are obtained by asymmetric alkylation of aldehydes with diethylzinc by way of a new catalyst system, ((R)-thiolan-2-yl)diphenylmethanol and several metal alkoxides. The transition states are also discussed in terms of experimental results and theoretical calculation.