52126-27-9

Upstream product

• 98-85-1 1-Phenylethanol 
• 645-45-4 hydrocinnamic acid chloride 
• 2021-28-5 ethyl dihydrocinnamate 
• 501-52-0 3-Phenylpropionic acid 
• 14371-10-9 (E)-3-phenylpropenal 
• 1445-91-6 (S)-1-phenylethanol 
• 104-55-2 3-phenyl-propenal 
• 52126-26-8 dihydrocinnamic acid 1-phenylethyl ester 
• 54519-07-2 vinyl ester of 3-phenylpropionic acid 
• 100-41-4 ethylbenzene 
• 22767-96-0 Benzyl 3-phenylpropionate 
• 103-25-3 3-phenylpropanoic acid methyl ester 

Downstream Products

• 1517-69-7 (R)-1-phenylethanol 
• 52126-26-8 (R)-dihydrocinnamic acid 1-phenyl-ethyl ester 

Relevant academic research and scientific papers

Catalytic, Enantioselective β-Protonation through a Cooperative Activation Strategy

The NHC-catalyzed transformation of unsaturated aldehydes into saturated esters through an organocatalytic homoenolate process has been thoroughly studied. Leveraging a unique “Umpolung”-mediated β-protonation, this process has evolved from a test bed for homoenolate reactivity to a broader platform for asymmetric catalysis. Inspired by our success in using the β-protonation process to generate enals from ynals with good E/Z selectivity, our early studies found that an asymmetric variation of this reaction was not only feasible, but also adaptable to a kinetic resolution of secondary alcohols through NHC-catalyzed acylation. In-depth analysis of this process determined that careful catalyst and solvent pairing is critical for optimal yield and selectivity; proper choice of nonpolar solvent provided improved yield through suppression of an oxidative side reaction, while employment of a cooperative catalytic approach through inclusion of a hydrogen bond donor cocatalyst significantly improved enantioselectivity.

Self-supported N-heterocyclic carbenes and their use as organocatalysts

The study of N-heterocyclic carbenes (NHCs) as organocatalysts has proliferated in recent years, and they have been found to be useful in a variety of reactions. In an attempt to further expand their utility and to study their recyclability, we designed and synthesized a series of self-supported NHCs in which the catalytic carbene groups form part of a densely functionalized polymer backbone, and studied them as organocatalysts. Of the self-Supported NHCs examined, a benzimidazole derived polymer with flexible linkers connecting the catalytic groups was found to be the most efficient organocatalyst in a model benzoin condensation reaction, and thus it was used in a variety of such reactions, including some involving catalyst recycling. Furthermore, it was also used to catalyze a set of redox esterification reactions involving conjugated unsaturated aldehydes. In all of these reactions the catalyst afforded good yield of the desired product and its polymeric nature facilitated product purification.

Convenient and Simple Esterification in Continuous-Flow Systems using g-DMAP

The utility and applicability of polyethylene-g-polyacrylic acid-immobilized dimethylaminopyridine (g-DMAP) as a catalyst in a continuous-flow system were investigated for decarboxylative esterification. High catalytic activity toward acylation was provided by g-DMAP containing a flexible grafted-polymer structure. During decarboxylation, carboxylic acids and alcohols were converted cleanly using di-tert-butyl dicarbonate (Boc2O) as a coupling reagent, which reduced by-products. In addition, the use of Boc2O resulted in the formation of tert-butyl esters. These esterifications dramatically reduced the reaction time under continuous-flow conditions, with a residence time of approximately 2 min. This highly efficient esterification procedure will provide more practical industrial applications.

Modified Yamaguchi reagent: Convenient and efficient esterification

A convenient and efficient esterification method that used a modified Yamaguchi reagent (2,4,6-trichlorobenzoyl chloride-4-dimethylaminopyridine) and avoided use not only of intractable acid chloride but also of acid anhydrides was proposed. The reaction mechanism was described by Fourier transform infrared spectroscopy and supported by a density functional theory calculation.

A metal-free oxidative esterification of the benzyl C-H bond

An efficient metal-free oxidative esterification of benzyl C-H bonds was developed. Using tetrabutylammonium iodide as catalyst and tert-butyl hydroperoxide as co-oxidant, benzylic substrates could react smoothly with various carboxylic acids to give the esters with good to excellent yields. The method was also suitable for the O-protection of N-Boc amino acids. The reaction mechanism was primarily investigated and a radical process was proposed. Copyright

2,2-disubstituted propionic anhydrides: Effective coupling reagents for the kinetic resolution of secondary benzylic alcohols using BTM

A variety of optically active benzylic alcohols possessing aliphatic substituents at the C-1 position are produced by the kinetic resolution of racemic secondary alcohols using free carboxylic acids with 2,2-disubstituted propionic anhydrides and (+)-benzotetramisole (BTM). Evaluation of the efficiency of this asymmetric esterification using several anhydrides derived from aliphatic carboxylic acids were carried out by comparing the efficiencies of the kinetic resolution of (±)-1-phenyl-l-propanol. It was found that not only pivalic anhydride is a very widely usable reagent to produce the corresponding esters with high ee's in the presence of BTM, but other 2,2-disubstituted propionic anhydrides, such as 2-methyl-2-phenylpropionic anhydride (MPPRA) and 2,2-diphenylpropionic anhydride (DPPRA), are also applicable as effective coupling reagents for producing the optically active esters and alcohols with high selectivities. This protocol directly provides chiral carboxylic esters from free carboxylic acids and racemic secondary alcohols by utilizing the transacylation process to generate mixed anhydrides from the acid components and sterically hindered carboxylic anhydrides.

Protonation of homoenolate equivalents generated by N-heterocyclic carbenes

Homoenolate equivalents are generated by Lewis basic N-heterocyclic carbene catalysts and then protonated to generate efficiently saturated esters from unsaturated aldehydes. This reactivity is extended to the generation of β-acylvinyl anions from alkynyl aldehydes. The asymmetric protonation of a homoenolate equivalent generated from a β,β-disubstituted aldehyde can be accomplished with a chiral N-heterocyclic carbene. Georg Thieme Verlag Stuttgart.

A versatile, practical, and inexpensive reagent, pyridine-3-carboxylic anhydride (3-PCA), for condensation reactions

A highly useful method for the preparation of carboxylic esters and carboxamides from various carboxylic acids was established by using a novel condensing reagent, pyridine-3-carboxylic anhydride (3-PCA), in the presence of 4-(dimethylamino)pyridine as an activator. The reactions of various carboxylic acids with nucleophiles, such as alcohols or amines, afforded the corresponding carboxylic acids or carboxamides in good to high yields under mild conditions by using simple experimental procedure. In addition, it was confirmed that this protocol was applicable to a gram-scale synthesis and the by-products, including pyridine-3-carboxylic acid and pyridine-3-carboxylate (or pyridine-3- carboxamide) produced in situ, were easily removed by using a simple aqueous workup.

Mild, powerful, and robust methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively

We developed two efficient practical methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively. The present mild and robust reaction was performed by two separate methods both by combining cheap and readily available amines, N-methylimidazole, and N,N,N′,N′-tetramethylethylenediamine (TMEDA). Method A uses catalytic N-methylimidazole and TMEDA with an equimolar amount of K2CO3, whereas Method B uses equimolar amounts of N-methylimidazole and TMEDA. The salient features are as follows. (i) With regard to reactivity, Method B was superior to Method A for esterification and thioesterification, whereas cost-effective Method A was superior to Method B for amide formation. (ii) Amide formation proceeded smoothly between acid chlorides and less nucleophilic and stereocongested amines such as 2,6-dichloroaniline. (iii) This protocol was applied to the successful synthesis of two agrochemicals, bromobutide and carpropamid.

Pyridine-3-carboxylic anhydride (3-PCA): A versatile, practical, and inexpensive reagent for condensation reaction between carboxylic acids and alcohols

A synthesis of carboxylic esters from various carboxylic acids and alcohols is successfully carried out by using a condensation reagent, pyridine-3-carboxylic anhydride (3-PCA). This reaction materialized synthesis of various carboxylic esters to be carried out under mild conditions by simple experimental procedure. Copyright