1.2- Dichloroethane alkylation with

Reaction of 2,2 -thiodiethanethiol with 1,2-dichloroethane yielded 37% of 1,4,7-trithionane <1995T4065>. A convenient synthesis of 2,3-pyrimidinophanes 226 has been described starting from 6-aryl-5-cyano-2-thiouracils (Equation 25) <2003JCM380>. A reaction of 2-thiouracil with dibromomethane and a sequential second S-alkylation with dibromoethane under basic conditions produced 2,3-pyrimidinophane 226 in 11% yield. 

Starting from sodium dithiocarbaminate 565, prepared quantitatively from methylamine and carbon disulfide, the iminodithiolane 566 was synthesized via alkylation with 1,2-dichloroethane. Further, efficient alkylation of latter with trimethylsilylmethyl triflate gave a stable crystalline salt 567 quantitatively (Scheme 78) <1995TL9409>. 

Diphenylcyclopropenone (2.06 g, 10 mmol) was dissolved in anhyd 1,2-dichloroethane (20 mL) and alkylated with triethyloxonium tetrafluoroborate (1.90 g, 10 mmol). After 15 min, a solution of 5,5-dimethylcyclohexane-l,3-dione (1.40 g, 10 mmol) in 1,2-dichloroethane (20 mL) was added then a solution of i-PfjNEt (1.30 g, 10 mmol) in 1,2-dichloroethane (20 mL) was added dropwise over a 90-min period with efficient stirring. Then, the resulting solution was stirred for a further 3 min and the solvent was evaporated in vacuo. The residue was triturated with benzene (40 mL) and the precipitated amine hydro-tetrafluoroborate salt was filtered off. Evaporation of the benzene solution yielded the main portion of crude product a second (minor) crop was obtained as insoluble material when the hydrotetrafluoroborate salt was dissolved in HjO. Both fractions were combined and recrystallized (EtOH) yield 2.10 g (64%) mpl98-199=C. 

The stereochemistry of bromination is usually anti for alkyl-substituted alkynes. A series of substituted arylalkynes has been examined in dichloroethane. As with alkenes, a TT-complex intermediate was observable. The A// for formation of the complex with 1-phenylpropyne is about —3.0kcal/mol. The overall kinetics are third order, as for an Ad S mechanism. The rate-determining step is the reaction of Br2 with the TT complex to form a vinyl cation, and both syn and anti addition products are formed. 

Dichloro-3-alkanones. The title reagent, which is generated from 1,1-dichloroethane, reacts with esters at low temperatures to give mixed alkyl-silyl acetals of 2,2-dichloro-3-alkanones. The dichloroketones are obtained directly from reaction of MOM esters. 

Several rhodium(I) complexes have also been employed as ATRP catalysts, including Wilkinson s catalyst, (177),391 421 422 ancj complex (178).423 However, polymerizations with both compounds are not as well-controlled as the examples discussed above. In conjunction with an alkyl iodide initiator, the rhenium(V) complex (179) has been used to polymerize styrene in a living manner (Mw/Mn< 1.2).389 At 100 °C this catalyst is significantly faster than (160), and remains active even at 30 °C. A rhenium(I) catalyst has also been reported (180) which polymerizes MM A and styrene at 50 °C in 1,2-dichloroethane.424... 

An improved synthesis of 3,4-dihydro-2,l-benzothiazine 2,2-dioxide was reported by Togo and co-workers using photochemical conditions . Treatment of A-alkyl 2-(aryl)ethanesulfonamides 18 with (diacetoxyiodo)arenes under irradiation with a tungsten lamp at 20-30 °C afforded 2,1-benzothiazines 19 and 20. Chemical yields and selectivities were dependent upon the choice of solvents and the reactant s substituents 18 (Table 1). When THF and EtOH were used as solvents, the reactions failed to give the cyclized products, since their a-hydrogen was abstracted by the intermediate sulfonamidyl radical. Compound 20 was obtained as a major product when 1,2-dichloroethane was employed as a solvent. In contrast, in the case of EtOAc as solvent, compound 19 was obtained as the major product. 

Solid-liquid phase systems with no added solvent produce esters in high yield [e.g. 2, 3] and are particularly Useful when using less reactive alkyl halides [e.g. 15], for the preparation of sterically hindered esters [16], or where other basic sites within the molecule are susceptible to alkylation, e.g. anthranilic acid is converted into the esters with minimal A-alkylation and pyridine carboxylic acids do no undergo quat-emization [17]. Excellent yields of the esters in very short reaction times (2-7 minutes) are also obtained when the two-phase system is subjected to microwave irradiation [18]. Direct reaction of the carboxylic acids with 1,2-dichloroethane under reflux yields the chloroethyl ester [19], although generally higher yields of the esters are obtained under microwave conditions [20]. 

Compound 10 was converted into allyl glycoside 11 in 73 yield in two steps, (a) Bu2Sn0CH2CH=CH2—SnCl,(4), and (b) MeONa—MeOH. Treatment of 11 with dimethoxypropane and TsOH, and then with benzyl bromide— NaH—DMF afforded compound 12 in 51% yield. Solvolysis of compound 12 in MeOH—AcOH, and then monobenzylation by the stannylation— alkylation method(5) gave the desired glycosyl acceptor 8 in 67% yield. Acetylation of compound 8 and then deallylation with PdCl2— AcONa in aq.AcOH(6) afforded a 93% yield of hemiacetal 13, which was treated with (a) SOCI2—DMF in dichloroethane(7) and (b) AgF— CH CN(8) to give the desired fluoride 9 in 73% overall yield. 

Mitotane Mitotane, l,l-dichloro-2-(o-chlorophenyl)ethane (30.5.8), is made by alkylating chlorobenzene with l-(2-chlorophenyl)-2,2-dichloroethane (30.5.7) in the presence of sulfuric acid. The necessary l-(2-chlorophenyl)-2,2-dichloroethanol (30.5.7) is in turn made from reacting 2-chlorophenylmagnesinmbromide with dichloroacetic aldehyde [135]. 

One of the major advantages of oxonium salts is that alkylations can be effected under reaction conditions that are generally much milder than those necessary with the more conventional alkyl halides or sulfonates. Triethyloxonium tetrafluoroborate, for example, has usually been employed at room temperature in dichloromethane or dichloroethane solution. Occasionally chloroform16-22 or no solvent at all4-20 is used. Difficult alkylations can be effected in refluxing dichloroethane.29 30 The less soluble trimethyloxonium tetrafluoroborate has been used as a suspension in dichloromethane or dichloroethane, or as a solution in nitromethane or liquid sulfur dioxide. Reports of alkylations in water23 and trifluoroacetic acid21 have also appeared. Direct fusion with trimethyloxonium tetrafluoroborate has succeeded in cases where other conditions have failed.25-30... 

The other possible isomer, 1,4-dimethylpyrazole (and its other N-alkyl and -aryl analogues), reacted with chlorine in dichloroethane at 25-35°C to produce 5-chloro derivatives in around 70% yields (90EUP366329). 5-Aryl-3-methylpyrazoles were chlorinated by NCS at C-4 (86JHC459), as were a range of pyrazoles by chloroperoxidase in the presence of hydrogen peroxide and potassium chloride at pH 2.9. Yields of 68-83% make this latter process an improvement over some traditional chemical methods (87JHC1313). 

Compared to oxabenzonorbomenes, oxabicyclo[2.2.1]heptenes or oxabicyclo[3.2.1] octenes are less reactive substrates, and the Pd-catalyzed alkylative ring-opening process with organozinc reagents generally required heating in 1,2-dichloroethane at reflux. The addition of Zn(OTf)2 dramatically improved the rate of the reaction which could be carried out in CH2C12 at room temperature, as illustrated for the conversion of 83 to the... 

The susceptibility of the mercaptide groups in these Schiff base complexes to ligand reaction was evaluated by treating these compounds with methyl iodide and benzyl bromide in chloroform solution. The pure compounds isolated from these reaction mixtures were of the composition NiL.2RX, where L represents the tetradendate Schiff base and RX represents the alkyl halide added. These reactions proceed smoothly and the stoichiometry of the products implies that both sufur atoms are reactive. The products are monomeric in dichloroethane. They exhibit magnetic moments consistent with octahedral structures, and they behave as di-univalent electrolytes in coordinating, polar solvents. 

Bis(alkylideniminoxy)ethanes (124,128,131,135,140) are of potential value, particularly as chelating ligands for metal cations. A special investigation has been undertaken in order to increase their yields in the reaction of ketoximes with dichloroethane (88ZOR2538). As a result, special conditions have been found which allow l,2-bis(organylideniminoxy)ethanes to be synthesized from oximes of dialkyl or alkyl aryl (hetaryl) ketoximes and 1,2-dichloroethane and an alkali metal hydroxide suspension in DMSO in yields up to 78%. 

Catalytic oxidations of sulfides were carried out in 1,2-dichloroethane with cumyl hydroperoxide by using 10 mol % of the catalyst. The best enantioselectivity was achieved with complex 6c. However, sulfone was always produced as byproduct of the reaction. Even with a limited amount of hydroperoxide, the sulfone formation could not be avoided. For example, the reaction of methyl p-tolyl sulfide using 0.5 mol equiv. of cumyl hydroperoxide with respect to sulfide gave a 62 38 mixture of the corresponding (.S j-sulfoxide and sulfone. The reaction of benzyl phenyl sulfide led to the formation of (5)-sulfoxide (84% ee) and sulfone ([sulfox-ide]/[sulfone] = 77 23). It was established that sulfone was produced from the early stages of the reaction. It was also demonstrated that some kinetic resolution of the sulfoxide cooperated with the enantioselective oxidation of the sulfide. A unique feature of this oxidation system, as compared to those using various Ti(IV)/(DET) complexes, is the insensitivity of the enantioselectivity (40-60% ee at 0°C) to the nature of the alkyl group of sulfides Ar-S-alkyl. 

A study48 of the direct upper-rim alkylation of calix[n]arenes has shown that, with n = 8, reaction with isopropyl chloride in 1,2-dichloroethane with AICI3 gives isopropylation, whereas when n = 4 hydroxyisopropylation is observed. With n = 6 there is a mixture of products, indicating overall an increase in phenolic behaviour as n increases from 4 to 8. 

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