Thermal rearrangement of functionalized 1,2-divinylcyclopropane systems. A convenient synthesis of substituted 4-cyclohepten-1-ones

1986 ◽  
Vol 64 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Edward Piers ◽  
Max S. Burmeister ◽  
Hans-Ulrich Reissig
Keyword(s):  
Acid Hydrolysis ◽  
The Other ◽  
Thermal Rearrangement ◽  
Enol Ethers ◽  
Acyl Chlorides ◽  
Silyl Ethers ◽  
Convenient Synthesis ◽  
Enol Silyl Ethers ◽  
Hydrolysis Of ◽  
Subsequent Acid

Reaction of the acyl chlorides 14–21 with lithium (phenylthio)(cis-2-vinylcyclopropyl)cuprate (2) provided the ketones 22–29. Compounds 22–25, upon treatment with i-Pr2NLi-Me3SiCl, were converted cleanly into the enol silyl ethers 30–33, which gave the 1,4-cycloheptadienes 34–37 upon thermolysis (100–110 °C). Acid hydrolysis of the latter materials produced the corresponding 4-cyclohepten-1-ones 38–41. However, subjection of the cis-2-vinylcyclopropyl ketones 26–29 to i-Pr2NLi-t-BuMe2SiCl afforded, in each case, a mixture of isomeric enol ethers (26 → 42 + 44 (1:1); 27 → 43 + 45 (1:9); 28 → 56 + 58 (1:1); 29 → 57 + 59 (4:1)). Thermolysis (150–175 °C) of these mixtures, followed by acid hydrolysis of the resultant products, gave the 4-cyclohepten-1-ones 54, 55, 64, and 65, admixed with the corresponding 3-methylenecyclopentenes 52, 53, 62, and 63. On the other hand, treatment of the trans-2-vinylcyclopropyl ketones 70–74 with i-Pr2NLi–t-BuMe2SiCl provided exclusively or predominantly the enol ethers 75–79. Thermolysis (230 °C) of the latter materials and subsequent acid hydrolysis of the resultant products 80, 50, 51, 60, and 61 afforded the 4-cyclopenten-1-ones 38, 54, 55, 64, and 65.

Synthesis of functionalized bicyclo[3.2.1]octa-2,6-dienes by thermal rearrangement of substituted 6-exo-(1-alkenyl)bicyclo[3.1.0]hex-2-ene systems

1987 ◽  
Vol 65 (3) ◽  
pp. 670-682 ◽  
Author(s):  
Edward Piers ◽  
Grace L. Jung ◽  
Edward H. Ruediger
Keyword(s):  
Acid Hydrolysis ◽  
The Other ◽  
Silyl Ether ◽  
Thermal Rearrangement ◽  
Enol Ether ◽  
Silyl Ethers ◽  
Keto Esters ◽  
Other Hand ◽  
Enol Silyl Ethers ◽  
Hydrolysis Of

Thermolysis of each of the enol silyl ethers 31–35 affords, cleanly and efficiently, the bicyclo[3.2.1]octadienes 36–40, respectively. Similarly, thermal rearrangement of the enol silyl ether 50 provides the diene 51. Hydrolysis of 36, 37, and 39, and decarbomethoxylation of the resultant keto esters 41, 42, and 44, gives the ketones 46–48, respectively. The ketone 46 is also obtained by acid hydrolysis of 51. Conversion of 6-methyl-1-hepten-4-yn-3-ol (56) into the enol ether 63 is described. Thermolysis of 63 gives 64, which, upon acid hydrolysis, affords 65. Thermolysis of the enones 68 and 69 produces the bicyclic dienones 70 and 71, respectively. On the other hand, thermolysis of 73 and 74, derived from the enone 69, provides the C-8 exo substituted bicyclo[3.2.1]octa-2,6-dienes 75 and 76, which are transformed smoothly, by acid hydrolysis, into the ketones 77 and 78, respectively.

Five-membered ring spiro-annulation via thermal rearrangement of enol silyl ethers of 2-(cyclopropylmethylene)cycloalkanones. A formal total synthesis of some spirovetivane-type sesquiterpenoids

1983 ◽  
Vol 61 (2) ◽  
pp. 288-297 ◽  
Author(s):  
Edward Piers ◽  
Cheuk Kun Lau ◽  
Isao Nagakura
Keyword(s):  
Total Synthesis ◽  
Acid Hydrolysis ◽  
Pyridinium Chlorochromate ◽  
Thermal Rearrangement ◽  
Similar Sequence ◽  
Silyl Ethers ◽  
Tertiary Alcohols ◽  
Enolate Anion ◽  
Enol Silyl Ethers ◽  
Hydrolysis Of

Treatment of the 2-(iodomethylene)cycloalkanones 10 and 11 with lithium (phenylthio)(cyclopropyl)cuprate provided good yields of the corresponding β-cyclopropyl enones 12 and 13, respectively. Thermolysis of the latter substances produced relatively poor yields of the desired spiro-annulation products 14 and 15. However, conversion of 12 and 13 into the corresponding enol silyl ethers 24 and 25, followed by thermal rearrangement of the latter materials and acid hydrolysis of the resulting products, provided synthetically useful yields of the spiro enones 14 and 15. Cuprous iodide-catalyzed addition of methyl magnesium iodide to 2-cyclohexen-1-one, followed by trapping of the resultant enolate anion with cyclopropanecarboxaldehyde, provided the ketols 38, which could be converted readily into the mixture of enol silyl ethers 34 and 35. Thermal rearrangement of the latter substances gave, after acid hydrolysis of the crude thermolysate, the spiro enones 42 and 43 in a ratio of ~2.5:1 (57% yield). Treatment of 42 with methyllithium in ether gave the tertiary alcohols 44 and 45 (ratio ~4:1). Hydroboration (disiamylborane, tetrahydrofuran; H2O2, NaOH) of 44, followed by oxidation of the resultant diol 46 with pyridinium chlorochromate, provided the ketol 47. A similar sequence of reactions converted the olefinic alcohol 45 into the ketol 49. Dehydration (p-toluenesulfonic acid in benzene) of 47 gave the spiro enones 28 and 48, in a ratio of ~9:1. Compound 28, also prepared previously from the ketol 49, had been converted earlier into the spirovetivane-type sesquiterpenoids (±)-α-vetispirene (29), (±)-β-vetivone (30), (±)-hinesol (31), (±)-hinesol acetate (32), and (±)-agarospirol (33).

ChemInform Abstract: Convenient Synthesis of β-Silyl Ketones from β-Stannyl Enol Silyl Ethers via a (1,4) Anionic Rearrangement of Silicon.

ChemInform ◽  
2010 ◽  
Vol 22 (14) ◽  
pp. no-no
Author(s):  
H. NAKAHIRA ◽  
I. RYU ◽  
A. OGAWA ◽  
N. KAMBE ◽  
N. SONODA
Keyword(s):  
Silyl Ethers ◽  
Convenient Synthesis ◽  
Enol Silyl Ethers

The Synthesis of Trisubstituted Enol Ethers and of Methyl Ketones from Ketones

1973 ◽  
Vol 51 (6) ◽  
pp. 981-983 ◽  
Author(s):  
Gilles Caron ◽  
Jean Lessard
Keyword(s):  
Acid Hydrolysis ◽  
Hydroxy Acid ◽  
Reliable Method ◽  
Acid Salt ◽  
Methyl Ketones ◽  
Enol Ether ◽  
Mild Acid Hydrolysis ◽  
Enol Ethers ◽  
Hydrolysis Of ◽  
Mild Acid

A reliable method for the synthesis of trisubstituted enol ethers (and of the corresponding methyl ketones) is described involving the condensation of the α-lithiated 2-methoxypropionic acid salt with a ketone to give a β-hydroxy acid, the cyclization to a β-lactone which is then decarboxylated (and mild acid hydrolysis of the enol ether).

The products of hydrolysis of cyclic orthoesters as a function of pH and the theory of stereoelectronic control

1985 ◽  
Vol 63 (9) ◽  
pp. 2485-2492 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Jean Lessard ◽  
Yves Nadeau
Keyword(s):  
Acid Hydrolysis ◽  
Hydroxy Ester ◽  
The Other ◽  
Relative Percentage ◽  
Stereoelectronic Control ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

The acid hydrolysis of cyclic orthoesters 1, 3–6 (R = Me), and 2 (R = Me and Et) as a function of pH was studied. The bicyclic orthoester 5 yields mainly the hydroxy-ester (less than 5% lactone), and this result is essentially independent of pH. For the other orthoesters, the relative percentage of products differs for each case and varies with pH. At pH ≤ 3, the percentage of lactone is always larger than at pH > 3. These results are explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates.

Partial hydrolysis of acyl 1,6-anhydro-β-D-glucopyranose

1984 ◽  
Vol 49 (8) ◽  
pp. 1780-1787 ◽  
Author(s):  
Štefan Kučár ◽  
Juraj Zámocký ◽  
Juraj Zemek ◽  
Dušan Anderle ◽  
Mária Matulová
Keyword(s):  
Acid Hydrolysis ◽  
Hydrazine Hydrate ◽  
Hydrogen Chloride ◽  
Ester Group ◽  
The Other ◽  
Hydroxyl Group ◽  
Partial Hydrolysis ◽  
Substantial Influence ◽  
Hydrolysis Of ◽  
Derivatives Of

Partial hydrolysis of per-O-acetyl- and per-O-benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose with methanolic hydrogen chloride and hydrazine hydrate was investigated. The acyl group at C(3) is of substantial influence on the course of hydrolysis. The esterified hydroxyl group at C(3) was found to be most stable on acid hydrolysis with methanolic hydrogen chloride when compared with that at C(2), or C(4); on the other hand, this ester group is the most labile upon hydrolysis with hydrazine hydrate. Selectivity of the respective ester groups towards hydrolysis made it possible to prepare all variations of acetyl and benzoyl derivatives of 1,6-anhydro-β-D-glucopyranose.

scholarly journals Convenient Synthesis of β-Silyl Ketones from β-Stannyl Enol Silyl Ethers via a [1,4] Anionic Rearrangement of Silicon

1990 ◽  
Vol 63 (11) ◽  
pp. 3361-3363 ◽  
Author(s):  
Hiroyuki Nakahira ◽  
Ilhyong Ryu ◽  
Akiya Ogawa ◽  
Nobuaki Kambe ◽  
Noboru Sonoda
Keyword(s):  
Silyl Ethers ◽  
Convenient Synthesis ◽  
Enol Silyl Ethers

scholarly journals Is Steam Explosion a Promising Pretreatment for Acid Hydrolysis of Lignocellulosic Biomass?

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1626
Author(s):  
David Steinbach ◽  
Andrea Kruse ◽  
Jörg Sauer ◽  
Jonas Storz
Keyword(s):  
Acid Hydrolysis ◽  
Lignocellulosic Biomass ◽  
Steam Explosion ◽  
Complex Structure ◽  
Beech Wood ◽  
Soluble Sugars ◽  
Water Soluble ◽  
Special Importance ◽  
Hydrolysis Of ◽  
Subsequent Acid

For the production of sugars and biobased platform chemicals from lignocellulosic biomass, the hydrolysis of cellulose and hemicelluloses to water-soluble sugars is a crucial step. As the complex structure of lignocellulosic biomass hinders an efficient hydrolysis via acid hydrolysis, a suitable pretreatment strategy is of special importance. The pretreatment steam explosion was intended to increase the accessibility of the cellulose fibers so that the subsequent acid hydrolysis of the cellulose to glucose would take place in a shorter time. Steam explosion pretreatment was performed with beech wood chips at varying severities with different reaction times (25–34 min) and maximum temperatures (186–223 °C). However, the subsequent acid hydrolysis step of steam-exploded residue was performed at constant settings at 180 °C with diluted sulfuric acid. The concentration profiles of the main water-soluble hydrolysis products were recorded. We showed in this study that the defibration of the macrofibrils in the lignocellulose structure during steam explosion does not lead to an increased rate of cellulose hydrolysis. So, steam explosion is not a suitable pretreatment for acid hydrolysis of hardwood lignocellulosic biomass.

Measurement of β-Glucan in Mushrooms and Mycelial Products

2016 ◽  
Vol 99 (2) ◽  
pp. 364-373 ◽  
Author(s):  
Barry V McCleary ◽  
Anna Draga
Keyword(s):  
Enzymatic Hydrolysis ◽  
Glucose Oxidase ◽  
Acid Hydrolysis ◽  
Trifluoroacetic Acid ◽  
Ganoderma Lucidum ◽  
Reliable Method ◽  
The Other ◽  
Free Glucose ◽  
The Difference ◽  
Hydrolysis Of

Abstract A robust and reliable method has been developed for the measurement of β-glucan in mushroom and mycelial products. Total glucan (plus free glucose and glucose from sucrose) was measured using controlled acid hydrolysis with H2SO4 and the glucose released specifically was measured using glucose oxidase/peroxidase reagent. α-Glucan (starch/glycogen) plus free glucose and glucose from sucrose were specifically measured after hydrolysis of starch/glycogen to glucose with glucoamylase and sucrose to glucose plus fructose with invertase and the glucose specifically measured with GOPOD reagent. β-Glucan was determined by the difference. Several acid and enzyme-based methods for the hydrolysis of the β-glucan were compared, and the best option was the method using H2SO4. For most samples, similar β-glucan values were obtained with both the optimized HCl and H2SO4 procedures. However, in the case of certain samples, specifically Ganoderma lucidum and Poria cocus, the H2SO4 procedure resulted in significantly higher values. Hydrolysis with 2 N trifluoroacetic acid at 120°C was found to be much less effective than either of the other two acids evaluated. Assays based totally on enzymatic hydrolysis, in general, yielded much lower values than those obtained with the H2SO4 procedure.

scholarly journals Stopped-Flow Kinetic Study of Reduction of Ferric Maltol Complex by Ascorbate

2016 ◽  
Vol 12 (4) ◽  
pp. 4338-4341
Author(s):  
Shabana Amin ◽  
Shazia Nisar ◽  
S Arif Kazmi
Keyword(s):  
Kinetic Study ◽  
Acid Hydrolysis ◽  
Rate Constant ◽  
Free Ligand ◽  
Low Ph ◽  
Reducing Agent ◽  
The Other ◽  
Stopped Flow ◽  
Kinetic Investigation ◽  
Hydrolysis Of

Stopped-flow kinetic investigation of reduction of Fe(III)-maltol complex is reported. The rates are dependent on pH in a complex way. On one hand at low pH there is a predominance of Fe(III)(maltol)2 which is easier to reduce compared to Fe(III) (maltol)3 which is more resistant to reduction. On the other hand ascorbate is a stronger reducing agent at higher pH. The rates are also found to be inversely dependent on the concentration of free ligand. These observations are explained by the following rate law:Rate = ((k0 +k1[H+])k2 [Asc-]/ (k-1[HMal] + k2[Asc-])) + k3 [Asc-] ) [FeIII(Mal)3] Here k1 is the rate constant for acid hydrolysis of the Fe(maltol)3 complex to Fe(maltol)2 complex and is directly controlled by H+, k0 is the rate constant for hydrolysis of the Fe(maltol)3 complex to Fe(maltol)2 complex and is an intrinsic process, k-1 is the rate constant of reformation of the tris complex by reaction of the bis complex and the free ligand, k2 is the rate constant for reduction of the bis complex by ascorbate and k3 is the rate constant for the reduction of the tris complex by ascorbate.

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