Triethylamine rearrangement

Seleno-Pummerer rearrangement. Diacetonylselenium dichlorides (1) when treated with triethylamine rearrange to a-chloro selenides (2).1... 

This dehydrochlorination occurs readily in the presence of a tertiary amine, such as triethylamine, and the reaction is similar to the dehydrochlorination of carboxylic acid chlorides to ketenes However, in the dehydrochlorination of the N-allylimidoyl chloride (CLXIX) with triethylamine, rearrangement to the nitrile CLXX occurs... 

Carboxylic acids react with butadiene as alkali metal carboxylates. A mixture of isomeric 1- and 3-acetoxyoctadienes (39 and 40) is formed by the reaction of acetic acid[13]. The reaction is very slow in acetic acid alone. It is accelerated by forming acetate by the addition of a base[40]. Addition of an equal amount of triethylamine achieved complete conversion at 80 C after 2 h. AcONa or AcOK also can be used as a base. Trimethylolpropane phosphite (TMPP) completely eliminates the formation of 1,3,7-octatriene, and the acetoxyocta-dienes 39 and 40 are obtained in 81% and 9% yields by using N.N.N M -tetramethyl-l,3-diaminobutane at 50 in a 2 h reaction. These two isomers undergo Pd-catalyzed allylic rearrangement with each other. 

Acyl derivatives of azoles containing two different environments of nitrogen atoms can rearrange. For example, 1-acyl-1,2,3-triazoles are readily isomerized to the 2H-isomers in the presence of triethylamine or other bases the reaction is intermolecular and probably involves nucleophilic attack by N-2 of one triazole on the carbonyl group attached to another (74AHC(16)33). 

However, depending on the nature of the initial heterocycle, rearrangements are possible. Alkylation of thiazole to form the thiazolium salt (390) and generation of the ylide (391) with triethylamine in the presence of DMAD gave not (392) but the isomeric product (393) by the rearrangement indicated (76JOC187). Rearrangements of these types are described in Chapters 4.07 and 4.19. 

In addition to (461), Dorn has described the imine (463) isolated from 5-amino-l-methylpyrazole and arenesulfonyl chloride (80CHE1). Upon heating, or in the presence of triethylamine, it undergoes rearrangement to the more stable 5-bis(arylsul-fonamido)pyrazoles (464). 5-Iminopyrazolines (461) react with acyl chlorides at the exocyclic nitrogen atom to afford amidopyrazolium salts (B-76MI40402). 

The bases most commonly used to effect rearrangement are hydroxides, alkoxides, alcoholic sodium bicarbonate and, in some instances, amines. In the rearrangement of a series of l,l-dibromo-2-keto-alkanes, where a direct comparison has been made between triethylamine and sodium methoxide, the amine has given slightly better results ... 

The sulfur analogue of the Hauser ortho-substitution rearrangement provides access to an arylacet-ic NSAID. Reaction of the aminobenzophenone 176 with ethyl methylthioacetate and tert-butyl hypochlorite gives the intermediate 178. The reaction probably proceeds by way of formation of the S-chlorinated sulfonium derivative 177 displacement on sulfur will lead to the salt 178. Treatment with triethylamine leads initially to the betaine 179. Electrocyelic rearrangement of that transient intermediate leads, after rearomatization, to the homoanthranilic acid 180. Internal ester-amine interchange leads then to indolone 181 [45]. The thiomethyl group is then removed with Raney niekel. Saponifieation of intermediate 182 affords bromfenac (183) [46J. 

The Curtius rearrangement procedure described here is a modification of one reported by Winestock. The submitters have found this procedure to be considerably more reproducible when N,N-diisopropylethylamine is substituted for triethylamine. The procedure described for the preparation of trans-2,4-pentadienoic acid is a modification of an earlier one by Doebner. The submitters have found this method to give reproducibly higher yields, and to be more convenient, than other commonly used procedures for preparing this material. The use of dichloromethane as the extracting and crystallizing solvent greatly simplifies the isolation of polymer-free samples of the crystalline acid. 

On reacting nitromethane and acrylonitrile in the presence of TCS 14/triethylamine in benzene (cf. also Scheme 7.42) the oxazolidine 1076, which is obtained in 85% yield, eliminates trimethylsilanol 4 in the presence of TsOH to give 40% d -oxazoline 1077 [104]. Heating of 1076, however, or treatment of 1076 with solid KF leads, via ring opening, elimination of HCN, and rearrangement to d-iso-oxazolidine 1078 in 82% yield this is converted by TsOH, with elimination of 4, into 83% isooxazole 1079 [104]. In contrast with 1076 the isooxazolidine 1080 de-... 

Sulfoxides containing an a-chloro group 1191 or an a-trimethylsilyl group 1193 rearrange on silylation with TMSOTf 20/triethylamine or with LDA followed by TCS 14 to the olefins 1192 and 1194 in 86 and 75% yield and HMDSO 7 [22, 23], whereas a sulfoxide with an a-cyano or a-carbomethoxy group as in 1195 reacts... 

TLC has been traditionally regarded as a simple, rapid, and inexpensive separation method, currently used mainly for preliminary examinations to give an indication of the number and variety of pigments present and help in the selection of suitable separation and purification procedures for further analysis. To avoid epoxy-furanoid rearrangements caused by inherent silica gel acidify, one pellet of a strong alkali such as KOH or NaOH should be added to the water used to make the thin layer, or in case of ready commercial plates, 0.1% triethylamine (TEA) should be added to the mobile phase. 

The synthesis was carried out as shown in Scheme 13.24. A diol was formed and selectively tosylated at the secondary hydroxy group (Step A-4). Base then promoted the skeletal rearrangement in Step B-l by a pinacol rearrangement corresponding to 23-11 => 23-III in the retrosynthesis. The key intramolecular Michael addition was accomplished using triethylamine under high-temperature conditions. 

The indenobenzazepines 314, obtainable from the corresponding protoberberines (Sections V,F,2 and V,G,2), were converted to the spirobenzyliso-quinolinediones 315 in 76% yield through hydrolytic bond cleavage and recyclization by sequential treatment with 4 N hydrochloric acid, bromine in acetic acid, and triethylamine, via the indanediones (Scheme 58) (166). A one-step stereoselective rearrangement of an indenobenzazepine to a spirobenzylisoquinoline was developed by Blasko et ah (167). O-Methylfumarofine (316)... 

This prediction was borne out for reactions of 2,3-dioxabicyclo[2.2.2]octane 2 27) and the 7-substituted-[2.2.1]-peroxides 10201 and 1121) which afforded 62b-d respectively upon treatment with either methanolic KOH or triethylamine. The bismercurated-[3.3.2]-peroxide 47 reacted similarly with aqueous NaOH, but the resultant 5-hydroxycyclooctanone underwent further rearrangement to the internal hemi-ketal.49)... 

Ozonolysis of alkene 446 in the presence of acetaldehyde afforded diketone 448 through the intermediacy of 447. Ring expansion through Beckmann rearrangement took place when bis-oxime 449 was mesylated and warmed in aqueous tetrahydrofuran (THF). The bis-lactam so formed gave piperidinediol 450 on reduction with lithium aluminium hydride, and this compound was transformed into ( )-sparteine by treatment with triphenylphosphine, CCI4, and triethylamine (Scheme 105) <20050BC1557>. 

The pyrido[l,2-tf][l,3,5]triazine-2,4(3//)-dione derivative 89 was obtained in a cycloaddition reaction of diphenyl-methyl isocyanate 90 with 2-pyridyl isocyanate 91 derived from the corresponding acyl azide via Curtius rearrangement <2002ARK438>. Compound 89 was also synthesized by the reaction of diphenylacetyl chloride 118 and picolinyl azide 116a in the presence of triethylamine (Scheme 11) <2002ARK438>. ... 

Tejedor and coworkers have utilized a combination of two domino processes for a microwave-promoted synthesis of tetrasubstituted pyrroles [344]. The protocol combines two coupled domino processes the triethylamine-catalyzed synthesis of enol-protected propargylic alcohols and their sequential transformation into pyrroles through a spontaneous rearrangement from 1,3-oxazolidines (Scheme 6.183). Overall, these two linked and coupled domino processes build up two carbon-carbon bonds, two carbon-nitrogen bonds, and an aromatic ring in a regioselective and efficient manner. The tetrasubstituted pyrroles could be directly synthesized from the enol-protected propargylic alcohols and the primary amines by microwave irradia-... 

Both forms have been isolated in a number of cases [Eq. (90)]. The ionic component has been obtained when diphenylboryloxymethyl(oxy-methyl)phenylphosphine sulfide is treated with triethylamine or pyridine. In the case of pyridine the complex is isolated by careful evaporation of benzene solvent. Unlike the ionic form, which is crystalline, the complex form is a liquid. In its IR spectrum there is an intense absorption of the hydroxyl groups and no absorption of the H—N+ bond. Spectra of benzene solutions of the complex and ionic forms are identical. With crystallization the complex form rearranges into the ionic form. 

Although the Wolf rearrangement of diazoketones in the presence of silver benzoate and triethylamine in methanol could involve rearrangement of an intermediate diradical or carbonium ion conjugate... 

Rearrangement reactions have provided access to some interesting azepinone or azepine dione systems. Curtius rearrangement followed by a [3,3] sigmatropic reaction on intermediate carbonyl azides gave azepin-2-one derivatives, for example 2, in fair to moderate yield. The precursor intermediates for this sequence were made, in turn, by treatment of 2-siloxysubstituted 2-alkenylcyclopropanecarboxylic acids (for example, 1) (Scheme 1) with diphenylphosphorazidate and triethylamine <00SL725>. 

After the formation of tautomeric anions A=A. the anion A a rearranges to give the anion B, which reacts with the second nitroso acetal molecule to form a mixture of stereoisomers of silyl derivative 509a. After desilylation of 509a, oxime 510a is isolated. The reaction with the fluoride anion proceeds at low temperature, whereas the use of triethylamine is efficient only at room temperature. The yield of oxime (510a) is virtually independent of the reaction conditions, whereas the diastereomeric ratio varies substantially. 

In the presence of triethylamine, the reaction of 2-amino-5-methyl[l,3,4]thiadiazole 134 with 2-benzyl-5-chloro-[l,2,4]thiadiazol-2-one 135 gives 3-(benzylcarbamoylimino)-6-methyl-3//-[l,3,4]thiadiazolo[2,3-c][l,2,4]thiadiazole 138. Presumably, the first-formed intermediate 136 rearranges through the thiapentalene intermediate 137 to the fused thiadiazole product 138 (Scheme 10) <1994T7019>. 

Apart from isolated reports summarized in Scheme 47, the chemistry of the fully conjugated ring systems has not been especially developed since CHEC-II(1996). In 1999, Monnier et al. reported the 1,3-dipolar cycloaddition of Reissert compound 160 with acrylates. Addition of triethylamine traps hydrofluoroboric acid and increases the proportion of milnchnone imine 160B the reaction therefore predominantly yields 1,3-adduct 161 which rearranges to 162 (Scheme 47) <1996BSB777, 1999EJ0297>. 

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