The Use of Diethyl Azodicarboxylate and Triphenylphosphine in Synthesis and Transformation of Natural Products
12 May 1981-Synthesis (© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to criminal prosecution. This applies in particular to photostat reproduction, copying, cyclostyling, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage.)-Vol. 1981, Iss: 01, pp 1-28
TL;DR: In this article, a reagent formed by combining diethyl azodicarboxylate (DEAD) and triphenylphosphine (TPP) could be utilized in the intermolecular dehydration between an alcohol and various acidic components such as carboxylic acids, phosphoric diesters, imides, and active methylene compounds.
Abstract: The reagent formed by combining diethyl azodicarboxylate (DEAD) and triphenylphosphine (TPP) could be utilized in the intermolecular dehydration between an alcohol and various acidic components such as carboxylic acids, phosphoric diesters, imides, and active methylene compounds. By the use of DEAD and TPP, diols and hydroxy acids gave cyclic ethers and lactones, respectively. The reaction of nucleosides with DEAD and TPP afforded triphenylphosphoranylnucleosides. Alcohols reacted with 2,6-di-t-butyl-4-nitrophenol in the presence of DEAD and TPP to give aci-nitroesters which converted into the corresponding carbonyl compounds.
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TL;DR: Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481 4.2.1.
Abstract: 3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481
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References
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TL;DR: In this article, the reaction of carboxylic acid with triphenyl phosphine and diethyl azodicarboxylate in the presence of an alcohol has been studied.
Abstract: When n-valeric acid was treated with allyl diethyl phosphite and diethyl azodicarboxylate, allyl valeriate and diethyl N-(diethyl)phosphoryl hydrazodicarboxylate were obtained in good yields. Similarly ethyl benzoate was obtained in a nearly quantitative yield by the reaction of benzoic acid with triethyl phosphite and diethyl azodicarboxylate. The reaction of carboxylic acid with triphenyl phosphine and diethyl azodicarboxylate in the presence of an alcohol resulted in the formation of the corresponding esters of the carboxylic acid, triphenyl phosphine oxide, and diethyl hydrazodicarboxylate. The mechanisms of these reactions are also discussed.
704 citations
95 citations
TL;DR: The benzoylation of various classes of diols by means of diethyl azodicarboxylate and triphenylphosphine was carried out at room temperature as mentioned in this paper.
Abstract: The benzoylation of various classes of diols by means of diethyl azodicarboxylate (1) and triphenylphosphine (2) was carried out at room temperature. When primary–secondary diols were treated with an equimolar amount of benzoic acid (3) in the presence of 1.5 molar equivalents of 1 and 2, reaction mainly Occurred at their primary hydroxyl functions. Secondary–secondary diols gave mono- and dibenzoylated products or cyclic ethers. The course of the reactions depends on the structure of diols used. Thus, intermolecular displacement giving benzoates is a favorable process for 1,3-butanediol, 2,4-pentanediol and trans-1,2-indanediol, while 2,5-hexanediol and trans-1,2-cyclohexanediol afford the cyclized products.
63 citations
TL;DR: Nucleophilic substitution reactions of Hydroxysteroids using Triphenylphosphane/diethylazodicarboxylate in benzene was described in this article, where it was not possible to run this substitution process in the hitherto used solvent THF.
Abstract: Nucleophilic Substitution Reactions of Hydroxysteroids using Triphenylphosphane/diethylazodicarboxylate
Nucleophilic substitution reactions by means of the title reagent on various more or less hindered steroid alcohols with suitable nucleophils in benzene is described. It was not possible to run this substitution process in the hitherto used solvent THF. Cholestan-3α-ol (1) was transformed to the 3β-substituted products 3β-benzoyloxy-cholestane (1a) and 3β-azido-cholestane (1b). Testosterone (2) affords with the corresponding nucleophils after short heating in benzene the inverted 17α-substituted products 3a, 3b and 3c. Analogously the 17α-azido-derivative 5a arises from 17β-hydroxy-androst-3-on (4). In the presence of a ketogroup in the substrate a competitive reaction can occur as it is shown in the case of cholestan-3-on (6): the products are the en-hydrazo-dicarboxylate-steroids 7a and 7b. The sterically very hindered 11α-position in 11α-hydroxy-4-pregnen-3,20-dion (8) can be transformed also to the 11β-azide 9a. The substitution of a 6β-hydroxy group in androstane-3β, 6β, 17β-triol-3,17-diacetate (10) to the 6α-azide 11a affords the elimination product 12 as main component. Trans-diaxial vicinal diols such as cholestane-2β,3α-diol (13) give a mixture of the α- and β-oxiranes 14a and 14b.
57 citations
TL;DR: The synthesis of pyrenophorin (I), a 16-membered dilactone metabolite of plant pathogenic fungi is described, which involves removal of the acetal groups and the addition of protected functional groups to the ethylene acetal.
Abstract: A new Synthesis of (±)-Pyrenophorin
The synthesis of pyrenophorin (I), a 16-membered dilactone metabolite of plant pathogenic fungi is described. Reaction of the Grignard reagent II with the activated succinic acid ester III gave the methyl (t-butyl)dimethylsilyloxy-oxo-octanoate IV which was converted into the corresponding ethylene acetal. Dehydrogenation via the benzeneselenenyl derivative lead to pyrenophorinic acid V with protected functional groups. Selective removal of silyl group followed by saponification of the ester group provided the ethylene acetal-hydroxy acid VI suitable for the cyclodimerisation reaction. This was effected with azodicarbonic acid ester and triphenylphosphine at −40° in a dilute toluene solution. The 16-membered dilactones VII with protected carbonyl groups were isolated in 24% yield. Silver-ion induced cyclodimerisation of the S-2-pyridyl carbothioate of VI gave much lower yields. Removal of the acetal groups lead to (±)-pyrenophorin (I) and meso-pyrenophorin in about equal amounts.
57 citations