Tscherniac‐Einhorn‐Synthesen mit Chlorolefinen und Acetylen

Bott, Kaspar

doi:10.1002/cber.19731060812

Cited by 8 publications

(11 citation statements)

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“…Thus, the 2-aryloxypropanals (3) obtained from aryl vinyl ethers (4) are used for the synthesis of (aryloxypropy1)amines (5); 3-arylbutanals (6), prepared from 2-arylalkenes (7). are intermediates for the synthesis of 3-arylbutylamines (S), and…”

Section: Intermediates For the Synthesis Of Pharmacologically Active mentioning

confidence: 99%

Synthesis of Intermediates by Rhodium‐Catalyzed Hydroformylation

Siegel¹,

Himmele²

1980

Angew. Chem. Int. Ed. Engl.

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Intramolecular additions of carbocations to a C-C triple bond or to a chlorovinyl group provide a pathway to cycloalkanones and cycloalkyl ketones. Such syntheses proceeding via ring closure which have already been redo not generally require a strongly acidic medium but can instead be performed in formic acid or trifluoroethanol. ConclusionThe methods considered in this review for the synthesis of carboxylic acids, aldehydes, and ketones are not only of preparative importance but also permit a further insight into the chemical behavior of carbocations. Thus the first generation of a "primary" vinyl cation [(55a)] devoid of stabilizing substituents was accomplished by addition of the I-adamantyl cation to acetylene and the reaction of this cation monitored. On the other hand, it has been found that the reactions of amidomethyl cations with chloroolefins in sulfuric acid do not involve a carbocation but an oxazonium ion as intermediate. These results could prove valuable for the planning of new syntheses. The availability of the starting materials should also encourage the exploitation of these reactions. (1971). (1978). Synthesis of Intermediates by Rhodium-Catalyzed Hydroformylation By Hardo Siegel and Walter Himmele[']Dedicated to Professor Matthias Seefelder on the occasion of his 60th birthdayThe reaction of olefins with carbon monoxide and hydrogen to give aldehydes is referred to as hydroformylation (0x0 reaction). As catalyst for this reaction rhodium is about three to four orders of magnitude more active than the more commonly employed cobalt. With special rhodium compounds, e. g. di-p-chlorobis(q-l,5-cyclooctadiene)dirhodium [RhCl(CsH1z)]z, in the presence of chiral phosphanes, even asymmetric hydroformylations can be achieved; however, the enantiomeric purity of the products (20-30%) is not high enough for industrial-scale syntheses.

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Section: Intermediates For the Synthesis Of Pharmacologically Active mentioning

confidence: 99%

Synthesis of Intermediates by Rhodium‐Catalyzed Hydroformylation

Siegel¹,

Himmele²

1980

Angew. Chem. Int. Ed. Engl.

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“…Since these syntheses normally take place in strong sulfuric acid, it was to be expected that suitable amidomethyl cations [from (a)] would react with the 1,l-dichloroolefins (7) to form N-acylated p-amino carboxylic acids.…”

Section: P-acylamino Carboxylic Acidsmentioning

confidence: 99%

“…Table 1) the weakly basic dichloroalkenes (7) require particularly electron-poor amidomethyl cations as reagents. In the choice of the amidomethylation agent (8) [a] The yields are based on the reactant used in substoichiometric amounts.…”

Section: P-acylamino Carboxylic Acidsmentioning

confidence: 99%

“…A further possibility for generation of amidomethyl cations consists in dissolving the carboxamide R'R*NH and (oligomeric) formaldehyde in sulfuric acid prior to addition of the olefin (7). The 1,l-dichloroolefins (7) and chloroolefins (46) used in the synthesis of P-(acylamino) carbaldehydes exhibit a clear gradation of reactivity towards the electrophilic reagent (a), which is manifested in the differing reaction temperatures.…”

Section: P-acylamino Carboxylic Acidsmentioning

confidence: 99%

“…P-Acylamino carboxylic acids (9) from 1,l -dichloroole!ins (7) and amidomethylating reagents (8 Thus, subsequent elimination of (1) from the intermediate (3) is practically impossible. As will be shown for a particular example (Section 2.3) the production of carbonyl compounds (4a-c) according to the given synthetic scheme has the decisive advantage that the adduct ions (3a-c) can be generated under much milder reaction conditions than is otherwise possible.…”

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