- Diastereoselectivity in the Carroll rearrangement of β-keto esters of tertiary allylic alcohols
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Carroll rearrangement of β-keto esters derived from tertiary allylic alcohols, for example, 7, under basic conditions followed by decarboxylation of the resulting β-keto acids yielded the expected γ, δ-unsaturated methyl ketones 8 with a range of olefin geometries from 100:0 to 1:1.8 E/Z, depending on the relative steric requirements of the two groups at the allylic center.
- Jung, Michael E.,Duclos, Brian A.
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Read Online
- Method for efficiently preparing alkynol
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The invention relates to a method for efficiently preparing alkynol, belongs to the field of preparation of chemical intermediates and chemicals, and particularly relates to a preparation method of alkynol. The preparation method comprises the following steps that 1, alkali metal is added into an anhydrous alcohols solvent; an alcohol-alkali metal solution is prepared; 2, a compound I is added into the alcohol-alkali metal solution; uniform stirring is performed; cooling is performed to be 0 DEG C or below; 3, acetylene is introduced through being metered at normal pressure; alkynol is obtained; 4, the alkynol solution after reaction is neutralized by ammonium chloride and a same alcohol mixed suspension system; 5, the neutralized mixed suspension system is filtered; after alcohols are recovered from filter liquid, reduced pressure distillation is performed to obtain an alkynol product. The method overcomes the defect that under the existing harsh reaction conditions of high pressure,liquid ammonia and the like, the solid potassium hydroxide feeding difficulty is avoided; under the ordinary pressure condition, the ketone compounds are converted into alkynol at high conversion rate. The method has the advantages of high conversion rate, simple process and good product purity.
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Paragraph 0036; 0037; 0038; 0043; 0044; 0045; 0046
(2018/12/14)
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- Evidence for concerted processes in the course of the homoallenylic transposition
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The hydrolysis of β-allenic tosylates produces mainly 2-methylenecyclobutanols resulting from a homoallenylic participation along with isomeric 2-methylenecyclobutanol minor products coming from a 1234-1243 rearrangement. Structures of various cyclopropylvinyl carbocations involved in the course of the hydrolysis have been determined by computational studies. For acyclic tosylates, the hydrolysis of one β-deuterated allenic tosylate confirmed the nucleophilic attack on the corresponding nonclassical carbonium ion before its evolution to a more stable cyclopropylvinyl carbocation. In the case of one cyclic β-allenic tosylate, the structure of the products has been checked by the use of deuterated isotopomer.
- Aouf, Chahinez,Galy, Nicolas,Santelli, Maurice
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supporting information
p. 3225 - 3233
(2013/04/24)
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- METHOD FOR THE PRODUCTION OF ACETYLENE ALCOHOLS
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The invention relates to a method for producing acetylene alcohols of general formula (I), wherein R1, R2 can independently be identical or different and represent optionally substituted hydrogen, an optionally substituted saturated, monounsaturated or polyunsaturated C1-C30 alkyl radical, aryl radical, cycloalkylalkyl radical, or cycloalkyl radical, or a group of general formula (II), wherein R3, R4 can independently be identical or different and represent optionally substituted hydrogen or an optionally substituted saturated, monounsaturated, or polyunsaturated C1-C30 alkyl radical, aryl radical, cycloalkylalkyl radical, or cycloalkyl radical while the dashed line can represent an additional double bond. Said acetylene alcohols are produced by monoethynylating a ketone of general formula R1-CO-R2 by (a) reacting lithium with a C1-C10 alkyl halide, (b) introducing acetylene gas, and (c) adding the ketone.
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Page/Page column 5-6
(2008/06/13)
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- A general and facile synthesis of substituted furans by palladium- catalyzed cycloisomerization of (Z)-2-en-4-yn-1-ols
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A general and facile synthesis of furans, based on Pd(II)-catalyzed cycloisomerization of (Z)-2-en-4-yn-1-ols, is described. Cycloisomerization reactions are carried out at 25-100 °C in the presence of a very simple catalytic system, consisting of K2PdI4, under essentially neutral conditions. This new methodology is very versatile and can be applied to the synthesis of a variety of substituted furans, including particularly fragile, naturally occurring furans such as rosefuran. Efficient synthetic approaches for the regioselective synthesis of suitably substituted (Z)-2-en-4-yn-1-ols have been developed.
- Gabriele,Salerno,Lauria
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p. 7687 - 7692
(2007/10/03)
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- Synthesis of a diterpene taxoid skeleton, bicyclo[9.3.1]pentadecatriene
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The synthesis of bicyclo[9.3.1]pentadecatriene skeleton was investigated by employing cyclization reactions using two key precursors bearing acetylene cobalt complex. Cyclization for the synthesis of strained twelve-membered ring was achieved via Nicholas type reaction in reasonable yield. Reductive decomplexation of the dicobalt hexacarbonyl moiety of the cyclization product was achieved with n-Bu3SnH in the presence of a catalytic amount of NBS in 1,4-cyclohexadiene solvent.
- Shibuya, Satoshi,Isobe, Minoru
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p. 6677 - 6698
(2007/10/03)
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- Versatile synthesis of bicyclo[9.3.1]pentadecatriene for new bicyclic taxoids
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A common carbon skeleton bicyclo[9.3.1]pentadecatriene of taxachitrienes was synthesized in its des-methyl form in short steps. The key step was Nicholas-Hosomi type reaction in the acidic cyclization between ene-yne biscobalthexacarbonyl complex electrophile with allyltrimethylsilane nucleophile. Decomplexation of the biscobalthexacarbonyl was achieved with a tin hydride and NBS in 1,4-cyclohexadiene solvent.
- Shibuya, Satoshi,Isobe, Minoru
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p. 373 - 374
(2007/10/03)
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- Effect of the metal catalyst on the mechanism of hydrogenation of C6 acetylenic carbinols
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The most probable mechanism of the hydrogenation of tertiary and of primary C6 acetylenic carbinols on group VIII metals are discussed.By using mathematical modelling and deuterium exchange methods we have shown that in the presence of Pd, Rh, and Pt the reaction takes place by a series mechanism, whereas on Ru black the acetylenic C6 alcohols are hydrogenated by a series-parallel scheme.
- Sokolo'skii, D. V.,Zhubanova, L. K.,Omarkulov, T. O.,Sadykov, U. A.,Korolev, A. V.
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- Ethynylation
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A process for the ethynylation of alpha, beta-unsaturated ketones to produce compounds containing the tertiary acetylenic alcohols which are useful as intermediates in carotenoids.
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- Process for producing ethynylating agents
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An ethynylating agent formed from mixing an anhydrous magnesium compound with sodium acetylide and its use in preparing ethynyl carbinols.
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