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1,3-Dicyclohexylcarbodiimide

(Babu) RajanBabu The Ohio State University, Columbus, OH, USA [Pg.133]

Solubility highly sol dichloromethane, THF, acetonitrile, DMF. Form Supplied in opalescent solid widely available. [Pg.133]

Handling, Storage, and Precautions is an acute skin irritant in susceptible individuals. Because of its low melting point, it is conveniently handled as a liquid by gentle warming of the reagent container. It should be handled with gloves in a fume hood, and stored under anhydrous conditions. [Pg.133]

Amide Formation. Since the initial reports, DCC has become the most common reagent in peptide synthesis and in other amide bond-forming reactions of primary and secondary amines with carboxylic acids. The mechanism is considered to be well understood. -  [Pg.133]

Typically, DCC (1.1 equiv) is added to a concentrated solution (0.1-1.0 M) of the carboxylic acid (1.0 equiv), amine (1.0 equiv), and catalyst (when used) in methylene chloride or acetonitrile at 0 °C. The hydrated DCC adduct, dicyclohexylurea (DCU), quickly precipitates and the reaction is generally complete within 1 h at rt. The solvents THF and DMF can be used, but are reported to reduce reaction rates and encourage the formation of the A -acylurea side product, as well as increasing racemization in chiral carboxylic acids.If the amine is initially present as the salt (i.e. amine hydrochloride), it may be neutralized by adding 1 equiv of Diisopropylethylamine prior to adding DCC however, the addition of tertiary amines (particularly Triethylamine) can facilitate A -acylurea formation and racemization. Racemization occurs via the formation of an oxazalone intermediate. The addition of coupling agents (acylation catalysts) such as 1-Hydroxybenzotriazole (HOBt), l-hydroxy-7-azabenzotriazole [Pg.133]


With the dicyclohexylcarbodiimide (DCQ reagent racemization is more pronounced in polar solvents such as DMF than in CHjCl2, for example. An efficient method for reduction of racemization in coupling with DCC is to use additives such as N-hydroxysuccinimide or l-hydroxybenzotriazole. A possible explanation for this effect of nucleophilic additives is that they compete with the amino component for the acyl group to form active esters, which in turn reaa without racemization. There are some other condensation agents (e.g. 2-ethyl-7-hydroxybenz[d]isoxazolium and l-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline) that have been found not to lead to significant racemization. They have, however, not been widely tested in peptide synthesis. [Pg.231]

In one method treatment of a solution containing the N protected and the C protected ammo acids with N N dicyclohexylcarbodiimide (DCCI) leads directly to peptide bond formation... [Pg.1139]

FIGURE 27 13 The mechanism of amide bond formation by W W dicyclohexylcarbodiimide promoted condensation of a carboxylic acid and an amine... [Pg.1140]

Step 3 The resin bound C terminal ammo acid IS coupled to an N protected ammo acid by using N N dicyclohexylcarbodiimide Excess reagent and N N dicyclohexylurea are washed away from the resin after coupling is complete... [Pg.1143]

Section 27 17 Peptide bond formation between a protected ammo acid having a free carboxyl group and a protected ammo acid having a free ammo group can be accomplished with the aid of N N dicyclohexylcarbodiimide (DCCI)... [Pg.1152]

Symmetrical or unsymmetrical diacyl peroxides (20, R, R = alkyl or aryl) can be synthesi2ed directiy from carboxyhc acids and hydrogen peroxide or from peroxycarboxyhc acids with dicyclohexylcarbodiimide or A/,A/-dicarbonyldiimida2ole as condensing agents (187) ... [Pg.125]

The most intensively studied oxidizing system is that developed by Pfitzner and Moflatt in which the oxidation is carried out at room temperature in the presence of dicyclohexylcarbodiimide (DCC) and a weak acid such as pyridinium trifluoroacetate or phosphoric acid. The DCC activates the DMSO which in turn reacts with the carbinol to give an oxysulfonium intermediate. This breaks down under mild base catalysis to give the desired ketone and dimethyl sulfide. [Pg.237]

Androst-4-ene-3,17-dione. Testosterone (0.58 g, 2 mmoles) is dissolved in a solution prepared from 3 ml of benzene, 3 ml of dimethyl sulfoxide, 0.16 ml (2 mmoles) of pyridine and 0.08 ml (1 mmole) of trifluoroacetic acid. After addition of 1.24 g (6 mmoles) of dicyclohexylcarbodiimide, the sealed reaction flask is kept overnight at room temperature. Ether (50 ml) is added followed by a solution of 0.54 g (6 mmoles) of oxalic acid in 5 ml of methanol. After gas evolution has ceased ( 30 min) 50 ml of water is added and the insoluble dicyclohexylurea is removed by filtration. The organic phase is then extracted twice with 5 % sodium bicarbonate and once with water, dried over sodium sulfate and evaporated to a crystalline residue (0.80 g) which still contains a little dicyclohexylurea. Direct crystallization from 5 ml of ethanol gives androst-4-ene-3,17-dione (0.53 g, 92%) in two crops, mp 169-170°. [Pg.239]

Electrostatic potential map for dicyclohexylcarbodiimide shows negatively-charged regions (in red) and positively-charged regions (in blue). [Pg.154]

Dicyclohexylcarbodiimide is a solid material, the Lewis structure for which resembles that of ketene. The molecule is a widely used catalyst for amide synthesis and other dehydration reactions. [Pg.154]

Analyze and describe the electronic structure of dicyclohexylcarbodiimide in the same way as you did for ketene. [Pg.154]

Which molecule, ketene or dicyclohexylcarbodiimide, appears to be more electrophilic Explain your rationale. [Pg.154]

Proceeding from 5 -0-acetylazauridine (80), a mixture of 2 - and 3 -monophosphates (81, 82) was prepared by phosphorylation with polyphosphoric acid, and these were converted into the 2, 3 -cyclic phosphate (83). From the 2, 3 -0-isopropylidene derivative of 3-methyl-6-azauridine the 5 -phosphate was prepared by treatment with cyanoethylphosphate and the corresponding diphosphate from its morpholidate through the action of phosphoric acid. ° Furthermore, a diribonucleoside phosphate (85) with a natural 3 -5 internucleotide linkage was prepared from 6-azauridine, The starting material for the preparation of such derivatives was 5 -0-acetyl-2 -0 -tetrahydro-pyranyluridine-3 -phosphate (84) which was condensed with di-G-acetylazauridine (86) or with 2b3 -0-isopropylidene-6-azauridine (76) with the aid of dicyclohexylcarbodiimide. ... [Pg.218]

Reaction of chromium hexacarbonyl with the derivative of tryptophan yields 99 (R = Me), which is hydrolyzed to 99 (R = H) and transformed into 99 (R = C6H4N02) when treated with p-nitrophenol and dicyclohexylcarbodiimide [82JOM(240)163],... [Pg.134]


See other pages where 1,3-Dicyclohexylcarbodiimide is mentioned: [Pg.80]    [Pg.63]    [Pg.144]    [Pg.307]    [Pg.1139]    [Pg.1140]    [Pg.1141]    [Pg.1142]    [Pg.307]    [Pg.127]    [Pg.73]    [Pg.32]    [Pg.34]    [Pg.63]    [Pg.113]    [Pg.56]    [Pg.148]    [Pg.293]    [Pg.330]    [Pg.487]    [Pg.1139]    [Pg.1139]    [Pg.1140]    [Pg.1141]    [Pg.150]    [Pg.698]    [Pg.700]    [Pg.800]    [Pg.154]    [Pg.569]    [Pg.250]   
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1.3- Dicyclohexylcarbodiimide Links

1.3- Dicyclohexylcarbodiimide amide formation

1.3- Dicyclohexylcarbodiimide anhydride formation

1.3- Dicyclohexylcarbodiimide ester formation

1.3- Dicyclohexylcarbodiimide heterocyclization reactions

1.3- Dicyclohexylcarbodiimide phosphate esters

A -dicyclohexylcarbodiimide

Carbodiimides dicyclohexylcarbodiimide

Cyclization agents/cyclizations dicyclohexylcarbodiimide

Dehydration with dicyclohexylcarbodiimide

Dicyclohexylcarbodiimide (DCC

Dicyclohexylcarbodiimide , amide

Dicyclohexylcarbodiimide , amide bond formation with

Dicyclohexylcarbodiimide , ester-linked

Dicyclohexylcarbodiimide 2+2] cycloaddition reactions

Dicyclohexylcarbodiimide Subject

Dicyclohexylcarbodiimide Swem oxidation

Dicyclohexylcarbodiimide acid

Dicyclohexylcarbodiimide acid addition

Dicyclohexylcarbodiimide diacetate

Dicyclohexylcarbodiimide in oxidation

Dicyclohexylcarbodiimide in oxidation of cholane-24-ol with dimethyl

Dicyclohexylcarbodiimide insertion reactions

Dicyclohexylcarbodiimide reagent

Dicyclohexylcarbodiimide ring closures

Dicyclohexylcarbodiimide, DMSO

Dicyclohexylcarbodiimide, DMSO Pfitzner-Moffatt oxidations

Dicyclohexylcarbodiimide, DMSO activator

Dicyclohexylcarbodiimide, activation

Dicyclohexylcarbodiimide, activation carboxylic acids

Dicyclohexylcarbodiimide, activator

Dicyclohexylcarbodiimide, activator dimethyl sulfoxide

Dicyclohexylcarbodiimide, as reagent

Dicyclohexylcarbodiimide, cyclization

Dicyclohexylcarbodiimide-4-Dimethylaminopyridine

Dicyclohexylcarbodiimides, polypeptides

Dimethyl sulfoxide-dicyclohexylcarbodiimide

N, A"-Dicyclohexylcarbodiimide

Peptides dicyclohexylcarbodiimide

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