Kulinkovich reaction

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Kulinkovich reaction

The Kulinkovich reaction describes the organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
of cyclopropanol

Cyclopropane

Cyclopropane is a cycloalkane molecule with the molecular formula C3H6, consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms....
s via reaction of ester

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
s with dialkyldialkoxytitanium reagents, generated in situ from Grignard reagents bearing hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
in beta-position and titanium(IV) alkoxides such as titanium isopropoxide

Titanium isopropoxide

Titanium isoproxide is a chemical compound with the chemical formula Ti4. This alkoxide of titanium is used in organic synthesis and materials science....
. Reaction was found by Kulinkovich and coworkers in 1989 . Titanium reagent could be used catalytically.

Titanium catalysts are ClTi(OiPr)₃ or Ti(OiPr)₄, ClTi(OtBu)₃ or Ti(OtBu)₄, Grignard reagents are EtMgX, PrMgX or BuMgX.

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The Kulinkovich reaction describes the organic synthesis

Organic synthesis

Cyclopropane

Ester

Hydrogen

Titanium isopropoxide

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules....
s: Ether

Ether

Ether is a class of organic compounds which contain an ether functional group ? an oxygen atom connected to two alkyl or aryl groups ? of general formula R?O?R....
s R-O-R, R-S-R, Imine

Imine

An imine is a functional group or chemical compound containing a carbon?nitrogen double bond . Due to their diverse reactivity, imines are common substrates in a wide variety of transformations....
s RN=CHR. Amide

Amide

In chemistry, an amide is one of three kinds of compounds:* the organic chemistry functional group characterized by a carbonyl group linked to a nitrogen atom , or a compound that contains this functional group ; or...
s, primary and secondary amine

Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
s, carbamate

Carbamate

Carbamates, or urethanes, are a group of organic compounds sharing a common functional group with the general structure -NHO-. Carbamates are esters of carbamic acid, NH2COOH, an unstable compound....
s are not stable to the reaction condition

An asymmetric version of this reaction is also known with a TADDOL-based catalyst .

Reaction mechanism

The generally accepted reaction mechanism

Reaction mechanism

In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs .Although only the net chemical change is directly observation for most chemical reactions, experiments can often be designed that suggest the possible sequence of steps in a reaction mechanism....
initially utilizes two successive stages of transmetallation of the committed organomagnesium compound, leading to an intermediate dialkyldiisopropyloxytitanium complex. This complex undergoes a dismutation to give an alkane molecule and a titanacyclopropane 1. The insertion of the carbonyl

Carbonyl

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double bond to an oxygen atom : C=O.The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex ; in this situation, carbon is triple-bonded to oxygen : C=O....
group of the ester

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
in the weakest carbon-titanium bond leads to a oxatitanacyclopentane 2 being rearranged to ketone

Ketone

In organic chemistry, a ketone is a type of organic compound which contains a carbonyl group bonded to two other carbon atoms in the form:Neither of the substituents R1 and R2 may be equal to hydrogen ....
3. Lastly, the insertion of the carbonyl group of 3 in the residual carbon-titanium connection forms a cyclopropane ring. In the transition state

Transition state

The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest energy along this reaction coordinate....
of this elementary stage, which is the limiting stage of the reaction, an agostic interaction

Agostic interaction

Agostic interaction is a term in organometallic_chemistry for the interaction of a coordinately-unsaturated transition metal with a carbon-hydrogen bonds, when the two electrons involved in the C-H bond enter the empty d orbital of a transition metal, resulting in a two electron three center bond....
stabilizing between the beta hydrogen and the R2 group and the titanium atom was called upon to explain the diastereoselectivity observed. Complex 4 obtained is a tetraalkyloxytitanium compound able to play a part similar to that of the starting tetraisopropyloxytitanate, which closes the catalytic cycle

Catalytic cycle

A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst . The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc....
. At the end of the reaction, the product is mainly in the shape of the magnesium alcoholate 5, giving the cyclopropanol after hydrolysis by the reaction medium.

The reaction mechanism of the Kulinkovich reaction was the subject of thorough calculations published in 2001 . Certain points remain nevertheless obscure and the mechanism of this reaction is actually not so simple. Intermediate titanium complexes of the ate

Ate complex

An ate complex in chemistry is a salt formed by reaction of a Lewis acid with a base whereby the central atom increases its Valence . Often in chemical nomenclature the phrase ate is suffixed to the element in question....
type were recently proposed by Kulinkovich .

Ligand exchange with olefins

In 1993, the team of Kulinkovich highlighted the aptitude of the titanacyclopropanes to undergo ligand exchange with olefins . This discovery was important, because it gave access to cyclopropanols more functionalized by making economic use of the Grignard of which normally at least two equivalents should have been engaged to obtain good outputs. Cha and its team introduced the use of cyclic Grignard reagents, particularly adapted for these reactions .

The methodology has been extended to intramolecular

Intramolecular

Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule; a property or phenomenon limited to the extent of a single molecule....
reactions

de Meijere variation

With amide

Amide

The intramolecular reaction is also known :

Szymoniak variation

In the Szymoniak variation the substrate is a nitrile

Nitrile

A nitrile is any organic compound which has a -Carbon=Nitrogen functional group. The -C=N functional group is called a nitrile group....
and the reaction product a cyclopropane with a primary amine

Amine

The reaction mechanism is akin the Kulinkovich reaction: