Asymmetrical dichloroethane

SYNONYMS asymmetrical dichloroethane, ethylidene chloride, 1,1-ethylidene dichlo-... 

Synonyms/Trade Names Asymmetrical dichloroethane Ethylidene chloride 1,1-Ethylidene dichloride... 

A closely related asymmetric synthesis of chiral sulphoxides, which involves a direct oxidation of the parent sulphides by t-butylhydroperoxide in the presence of metal catalyst and diethyl tartrate, was also reported by Modena and Di Furia and their coworkers-28-7,288 jjje effect 0f the reaction parameters such as metal catalyst, chiral tartrate and solvent on the optical yield does not follow a simple pattern. Generally, the highest optical purities (up to 88%) were observed when reactions were carried out using Ti(OPr-i)4 as a metal catalyst in 1,2-dichloroethane. 

As to most chiral atropisomeric ligand, resolution or asymmetric synthesis is requisite. Mikami developed a novel ligand-accelerated catalyst. The chirality of atropos, but achiral triphos ligand-Ru complex, can be controlled by chiral diamines. Using ( -dm-dabn as controller, the single diastereomeric triphos-Ru complex was achieved through isomerization of (i )-triphos-Ru complex in dichloroethane at 80 °G (Scheme l).44... 

CuOTf/PyBox System The first direct asymmetric addition of alkynes to imines, generated from aldehydes and amines in situ, was reported by using copper salts in the presence of chiral PyBox ligand (Scheme 5.2). The products were obtained in good yields and excellent enantioselectivities in most cases. When toluene was used as solvent, up to 93% yield and 99% ee were obtained. Up to 99.5% ee was obtained when the reaction was carried out in 1,2-dichloroethane. The reaction can also be performed in water smoothly, and good enantioselectivities (78-91% ee) were obtained. 

Asymmetric cyclization using chiral ligands offers powerful synthetic methods for the preparation of optically active compounds [39]. After early attempts [40,41], satisfactory optical yields have been obtained in a number of cases. Synthesis of the optically active cA-decalin system [42] was carried out with high enantioselectivity based on the differentiation of enantiotopic C=C double bonds [43]. The cyclization of the triflate 93 gave the cA-decalin 94 with 95% ee in 78% yield using (i )-BINAP. A mixture of 1,2-dichloroethane and f-BuOH is the best solvent, and the asymmetric synthesis of vemolepin (96) via Danishefsky s key intermediate 95 has been achieved [44]. 

The influence of solvents was extensively studied [38, 40b, 42], with reactions shown capable of being performed in neat, or, virtually in any polar medium. Whilst high dielectric constant oxygenated solvents such as tetrahydrofuran (THF), 1,4-dioxane, acetone (Et20), dimethyl sulfoxide (DMSO), and dimethyl-formamide (DMF) are used in non-asymmetric MBH reactions, dichloroethane (CH2C12) or acetonitrile are preferred for asymmetric transformations. MBH re-... 

The chiral acetals of a,p-enals derived from (H,R)-( -I-)-N,N,N, N -tetramethyltartaric acid diamide (9, 47-48) undergo either 1,4- or I. . .-addition of R,AI with high asymmetric induction. The course of reaction can be controlled by the choice of solvent. 1,4-Addition is favored in 1,2-dichloroethane (or toluene) 1,2 addition is the main or only reaction in chloroform. The adducts can be converted into optically active p-alkyl aldehydes or allylic alcohols (Chart I). ... 

We studied the partition equilibria and structures of the ion pair of cationic complex of polyether compounds with picrate ion and reported that the dissociation of ion pair in the organic phase plays an important role for the partition equilibria.In the present paper, the ion-pair formation in 1,2-dichloroethane was studied by using the one of the most simple system of electrolyte, tetraalkylammonium picrate. The effect of the chain length of the alkyl group was studied for the symmetric and asymmetric tetraalkylammonium ions. 

Differently from poly(7-benzyl S-glutamate) (PBLG), poly( -benzyl S-aspartate) (PBLA) is known to amme a left-handed a-helical conformation which is less stable than the a-helical conformation of PBLG (20). In this respect, it is of interest to examine the asymmetric addition of dodecanethiol to isopropenyl methyl ketone [Eq. (9)] catalyzed by the terminal amino group of PBLA. By using PBLA, prepared by the polymerization of the corresponding NCA in a mixture of 1,2-dichloroethane and tetrahydrofuran with butylamine as initiator, Fukushima and Inoue (21) observed the occurrence of asymmetric nthesis as own in Table 4. 

IR spectrum of triple mixture containing 1,2-dichloroethane as an additive apart from mustard gas and lewisite is presented on Fig.5. Judging from the fact that the bands at 1378 and 1010 cm 1 have relatively low intensity the sample contains lower quantity of mixed type of mustard gas in a comparison with usual one (absorption in the range of 1440-1400 cm"1 and at the band of about 1200 cm1). a-Lewisite shows up the strong bands at 933 and 1554 cm1. The last one has undoubtedly asymmetric form as it was for mustard gas-lewisite mixture what indicates the presence of P-lewisite in the sample. 

Asymmetric reduction of ketones. This chiral surfactant catalyzes the reduction of ketones by NaBH in H20-l,2-dichloroethane. More interestingly, the reaction is stereoselective ( + )-alcohols are formed in excess, the optical yield depending on the concentration of the catalyst. L-N-Methyl-N-hexadecylephedrinium bromide was also used, but optical yields of alcohols were lower with this reagent. Presumably the alkylephedrinium tetrahydroborate is formed in the aqueous phase and passes into the organic phase, where reduction occurs with stereoselectivity. ... 

Further optimization of asymmetric Mizoroki-Heck cyclizations of prochiral vinyl triflates focused on the effects of base, solvent and additives [30, 31]. Tertiary amine bases, such as -Pr2NEt, gave results inferior to those realized with K2CO3. In the absence of additives, reactions in toluene gave superior yields to reactions conducted in 1,2-dichloroethane (DCE) or polar solvents. However, additives such as tertiary alcohols (e.g. pinacol) or KOAc... 

Compounds 44 and 45 were found to be insoluble in many common organic solvents however, compound 44 dissolves in DCM and 1,2-dichloroethane on the addition of tetrabutylanunonium chloride or tetrabutylammonium acetate—an early indication of the anion-binding capacity of this receptor. Diffusion of ether into a DCM solution of 44 in the presence of tetrabutylanunonium chloride yielded crystals of the chloride complex of 44 suitable for X-ray diffraction. The crystal structure revealed that two distinct complexes were present in the solid state (Figure 32). In both cases, the strongest hydrogen bonds to the chloride anion are from the carbazole NH (NH Cl 2.22 and 2.33 A). In the first complex, the chloride anion is asymmetrically positioned within the cavity. 

Scheme 7.22 Cu-Catalyzed asymmetric oxidative cross-coupling of 2-naphthols. DCE = 1,2-dichloroethane.

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