Halogen‐diazoessigsäureäthylester aus Quecksilber‐bis‐diazoessigsäureäthylester

Schöllkopf, Ulrich; Gerhart, F.; Reetz, Manfred T.; Frasnelli, Hubert; Schumacher, Horst

doi:10.1002/jlac.19687160129

Cited by 29 publications

(5 citation statements)

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“…The halogenated EDAanalogues are less stable, and decompose within hours at room temperature, both as neat compounds and in solution. However, all three halogenated EDA-analogues can be conveniently handled in solution at 0 • C. 9 After having established an efficient procedure for the synthesis of the halogenated EDA-analogues, we turned to the use of these diazo compounds in the cyclopropanation of alkenes. Styrene was selected as the alkene in our initial attempts to make 1bromocyclopropanecarboxylates 4 (Scheme 2).…”

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confidence: 99%

Highly efficient formation of halodiazoacetates and their use in stereoselective synthesis of halocyclopropanes

2008

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Highly efficient formation of halodiazoacetates and their use in stereoselective synthesis of halocyclopropanes

2008

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“…The first syntheses of α-halodiazoacetates were reported around 1970, and relied on the formation of silver or mercury derivatives of ethyl diazoacetate (EDA) as intermediates [17][18][19][20][21]. Treatment with an electrophilic halogenating agent gave the chlorinated, brominated, and iodinated analogues of EDA in yields ranging from 30 to 90 %.…”

Section: Synthesis Of Halodiazoacetatesmentioning

confidence: 99%

Halodiazoacetates as useful tools for selective halo-functionalization

Bonge

Hansen

2011

Pure and Applied Chemistry

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The halodiazoacetates are a group of synthetically useful halogenated diazo compounds that can be used in Rh(II)-catalyzed carbenoid reactions. In the reactions between the halodiazoacetates and electron-rich, sterically unhindered alkenes, halocyclopropanes are formed in good to excellent yields. The halodiazoacetates also react well in C-H and Si-H insertion reactions, broadening the synthetic utility of these reactions. The products of the reactions are synthetically useful α-halocarbonyl compounds. Density functional theory (DFT) calculations have given insight into the mechanism of the cyclopropanation and C-H insertion reactions of the halodiazoacetates, and have also shown that the halodiazoacetates have a particularly high kinetic activity.

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“…The most general methods of synthesis of 1-halogeno-1cyclopropanecarboxylates are lithiation of gem-dihalogencyclopropanes by RLi with formation of 1-halogeno-1-lithiocyclopropanes and their subsequent interaction with carbon dioxide, 1 the reactions of diazocompounds with esters of substituted α-halogenoacrylic acids, 2 and also the reactions of esters of diazohalogenoacetic acids with unsaturated compounds. 3 In this present work 1-halogeno-1-cyclopropanecarboxylates have been prepared by thermal removal of nitrogen from pyrazolines, known to be a rather convenient method of synthesis of cyclopropanes. 4 On reaction of 7-aryl-1-methyl-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-en-4-carboxylates 1a-g 5 with chlorine in chloroform at 0°C, esters of 7-aryl-1-methyl-4-chloro-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-2-en-4-carboxylates 2a-g were formed as a mixture of endo-and exo-isomers in 69-84% yield (endo/exo-ratio -8:1) (Table ).…”

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“…3 In this present work 1-halogeno-1-cyclopropanecarboxylates have been prepared by thermal removal of nitrogen from pyrazolines, known to be a rather convenient method of synthesis of cyclopropanes. 4 On reaction of 7-aryl-1-methyl-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-en-4-carboxylates 1a-g 5 with chlorine in chloroform at 0°C, esters of 7-aryl-1-methyl-4-chloro-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-2-en-4-carboxylates 2a-g were formed as a mixture of endo-and exo-isomers in 69-84% yield (endo/exo-ratio -8:1) (Table).…”

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A New Synthetic Route to 1-Halogeno-1-cyclopropanecarboxylates

Molchanov¹,

Stepakov²,

Kostikov³

et al. 2000

Synlett

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Substituted bicyclic 1-halogeno-1-cyclopropanecarboxylates have been prepared by elimination of molecular nitrogen from 4-halogeno-7-aryl-1-methyl-2,3,7-triazabicylo[3.3.0]oct-2-en-4-carboxylates, which were obtained by the reaction of 7-aryl-1-methyl-2,3,7-triazabicyclo[3.3.0]oct-3-encarboxylates with halogens (Cl 2 , Br 2 ).The most general methods of synthesis of 1-halogeno-1-cyclopropanecarboxylates are lithiation of gem-dihalogencyclopropanes by RLi with formation of 1-halogeno-1-lithiocyclopropanes and their subsequent interaction with carbon dioxide, 1 the reactions of diazocompounds with esters of substituted α-halogenoacrylic acids, 2 and also the reactions of esters of diazohalogenoacetic acids with unsaturated compounds. 3 In this present work 1-halogeno-1-cyclopropanecarboxylates have been prepared by thermal removal of nitrogen from pyrazolines, known to be a rather convenient method of synthesis of cyclopropanes. 4On reaction of 7-aryl-1-methyl-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-en-4-carboxylates 1a-g 5 with chlorine in chloroform at 0°C, esters of 7-aryl-1-methyl-4-chloro-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-2-en-4-carboxylates 2a-g were formed as a mixture of endo-and exo-isomers in 69-84% yield (endo/exo-ratio -8:1) (Table).Heating of esters 2a-g in vacuo at 120°C led to the extrusion of nitrogen and the formation of esters of 1-chlorocyclopropanecarboxylic acids 3a-g. It is important to note, that thermolysis of endo-isomers 2a-d resulted only in endo-isomers 3a-d, while on heating for the same time the exo-isomer 2a-d formed a mixture of endo-and exoisomers 3a-d. Reaction of the pyrazolines 1h,j,m 5 with chlorine at 0°C in 1,2-dichloroethane resulted directly in esters of 1-chlorocyclopropanecarboxylic of acids 3n-p with an endo-configuration in yield 88-94% (Table).On reaction of ester 1a with bromine in chloroform at 60°C a bromopyrazoline 2h was obtained with a yield of 36%. In all probability, this had an exo-configuration; thermolysis of this in vacuo at 120°C resulted in the formation an ester 3h as a mixture of exo-and endo-isomers in the ratio 3.1:1 Reaction of pyrazolines 1h-l with bromine in glacial acetic acid at 70°C resulted directly in 1-bromocyclopropanecarboxylates 3i-m in 63-81% yield as a mixture of endo-and exo-isomers. Table Compounds 2 and 3 preparedTypical experimental procedures were as follows: Ethyl 7-p-tolyl-1-methyl-4-chloro-6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-2-en-4-endo-carboxylate (2a). Into a solution (0.35 g, 1.1 mmol) of ester 1a in of dry chloroform (30 ml) at 0°C was passed a stream of dry chlorine till saturation (excess, during 1 min). Chloroform was evaporated in vacuo at room temperature, and the residue (mixture endo/exo as 8:1) was crystallized from methanol to give ester endo2a; yield 0.27 g (69%), mp 98-99°C (dec.). 1 H NMR(300 MHz) δ: endo-2a -1.42 (t, 3H, J = 7 Hz), 2.01 (s 3H), 2.40 (s, 3H), 3.74 (s, 1H), 4.42 (q, 2H, J = 7 Hz), 7.15 (d, 2H, J = 8 Hz), 7.28 (d, 2H, J = 8 Hz); signals of exo-2a -3.43 (s, 1H), 3.88 (s, 3H), other signals...

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Halogen‐diazoessigsäureäthylester aus Quecksilber‐bis‐diazoessigsäureäthylester

Cited by 29 publications

References 5 publications

Highly efficient formation of halodiazoacetates and their use in stereoselective synthesis of halocyclopropanes

Highly efficient formation of halodiazoacetates and their use in stereoselective synthesis of halocyclopropanes

Halodiazoacetates as useful tools for selective halo-functionalization

A New Synthetic Route to 1-Halogeno-1-cyclopropanecarboxylates

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