Ethylamine, reaction with chloroform

Ethyl a-acetyl-j3-(2,3-dimethoxy-phenyl)acrylate, 31, 56, 58 Ethyl a-acetyl-/S-(3,4-dimethoxy-phenyl)acrylate, 31, 58 ETHYL a-ACETYL-/3-(2,3-DIMETH0XY-phenyl)propionate, 31, 56 Ethyl a-acetyl-j3-(3,4-dimethoxy-phenyl)propionate, 31, 58 Ethylamine, reaction with chloroform, 35, 64... 

A solution of 1.0 g of this product and 0.025 mL of 25% methanolic NaOMe (10 mL) was stirred at room temperature until the reaction was completed. The mixture was cautiously neutralized with Amberlite IR-120 (H+) ion-exchange resin. After filtration and concentration, the material was passed through a small bed of silical gel pretreated with 2% triethylamine in hexane. Elution with chloroform-methanol (8 1) containing 1% of tri-ethylamine gave the pure title compound as a pale yellow solid (0.61 g, 90%) mp 93°C, [a]D +4.0° (c 0.9, MeOH). 

The bis(77-cyclopentadienyl)zirconium dichloride has been synthesized by a variety of routes and a variety of authors. It can be recovered from reaction systems of zirconium tetrachloride and sodium cyclopentadienide in tetrahydrofuran or ethyleneglycol dimethyl ether 89, 194, 343, 471) or with lithium cyclopentadienide 472) in place of the sodium compound. The hafnium compound was prepared in a similar manner 343, 471). In general, the residue obtained upon evaporation of the solvent is extracted with chloroform and the product from the extraction is recrystallized from benzene. The dichloride was also prepared 451) by the continuous recirculation of cyclopentadiene vapor through a bed of ZrCl2 at 270°-350°C. Another route to the chloride is the reaction of zirconium tetrachloride with cyclopentadienylmagnesium chloride 559) in benzene yet another involves the reaction of zirconium tetrachloride and cyclopentadiene in ethylamine as the solvent at room temperature 367). 

Two classical methods based on methylamines 58a have been developed for preparation of substituted methyl isocyanides-the second component of the reaction shown in Scheme 4.28. The first method consists of one stage, namely, treatment of amines with chloroform in the presence of alkalis the second method consists of two stages. The reaction with ethyl formate leads to formamides 58b, which are then dehydrated by treating with phosphorus oxochloride in the presence of tri-ethylamine (Scheme 4.29) (Jacobsen et al. 1996a). 

N-Acyliminium ion-mediated Pictet-Spengler reaction has also been applied to the synthesis of tetrahydroisoquinolines [404]. Thus, supported 4-formylbenzoic acid (569) was reacted with 2-(3,4-dimethoxyphenyl)ethylamine (570), affording the corresponding resin-bound imine (571). The latter underwent N-acyliminium ion-mediated Pictet-Spengler condensation in the presence of a number of acid chlorides, sulfonyl chlorides, and a chloroformate under basic conditions to give (572) better yields and purities were obtained using acid chlorides and the chloroformate (Scheme 119). 

V- 6-[2-(7-methyl[l, 8]naphthyridin-2-yl)ethyl]pyridine-2-yl acetamide 356 was prepared by the reaction of 2,7-dimethyl-l,8-naphthyridines 357 with n-butyllithi-um and 2-/V-acetylamino-6-bromomethylpyridine 358. Another carrier, viz., N-(l-methyl[l,8]naphthyridin-2-yl)-7V -(6-methylpyridin-2-yl)isophtalamide 359, was synthesized from 2-amino-7-methyl-l,8-naphthyridine 360, 2-amino-6-methylpyridine 226a and isophthaloyl chloride 361 in dry dichloromethane in the presence of tri-ethylamine. N,N -bis(l-mcl y [, 8]naphthyridin-2-yl)isophthalamide 362 was prepared from naphthyridines 360 and chloride 361 under analogous conditions. Isophthalamides 359 and 362 were used for the determination of L-( + )tartaric acid as complexes (1 1) soluble in chloroform (1999JIC661, 2001T4987). 

Our first attempt was an enantioselective synthesis of (k)-(+)-carnegine [7,8]. Michael addition of 2-(3,4-dimethoxyphenyl)ethylamine (7) to (R)-(+)-l took place readily at room temperature in chloroform (Scheme 5). Without isolation of any intermediate, the reaction mixture was treated with excess trifluoroacetic acid to effect the cyclization. Depending on the reaction conditions and the aryl substituent of the chiral sulfoxide, different levels of diastereoselectivity were observed. The results are summarized in Table 1. Under proper conditions (TFA, 0°C, 4h), 10b could be obtained in 65% yield as the only isolated product (Scheme 5) (Table 1). 

A quantitative study of the s-trinitrobenzene-dimethylamine interaction in dioxane led to the conclusion that four amine molecules are involved to give a 1 4 complex (53). It was later shown that the spectroscopic data can be better accommodated by assuming three equilibria to form 1 1, 1 2, and 1 3 complexes, with the 1 3 complex responsible for most of the measured absorption. Structures comparable to those of Lewis and Seaborg were proposed for these adducts (54). A more detailed study in dioxape and chloroform (55) gave results in accord with this interpretation for the interactions of s-trinitrobenzene with methylamine, ethylamine, dimethylamine, and diethylamine. Only a 1 1 complex was observed with more bulky amines. In most cases it was possible to observe a fast reaction, probably to form a charge-transfer complex, as well as the slower reaction giving the above complexes. 

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