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Stereochemical Fate of the Isopropylidene Methyl Groups of Lanosterol during the Biosynthesis of Isofucosterol in Pinus Pinea
Lanosterol (16) was administered to Pinus pinea and the isofucosteryl acetate (6) obtained was chemically transformed into cholesterol (13).Compound (13) was incubated with rat-liver mitochondria to yield the propionic acid.The data obtained are consistent with a biosynthetic pathway in which the pro-E isopropylidene methyl group of the Δ24-precursor becomes the pro-R isopropyl methyl group in isofucosterol.
Nicotra, Francesco,Ronchetti, Fiamma,Russo, Giovanni,Lugaro, Giuseppe,Casellato, Marilena
p. 498 - 502
(1981)
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Novel Trifunctional Building Blocks for Fluorescent Polymers
(Matrix presented) Herein, we describe the synthesis of fluorescent 2-(arylsulfonyl)methacrylates and its polymers. These novel trifunctional monomers, possessing a fluorescent arylsulfonyl (ArSO2) group, an alkyl group (R), and a polymerizable olefin, serve as useful building blocks for functionalized fluorescent polymers.
Batra, Dolly,Shea, Kenneth J.
p. 3895 - 3898
(2003)
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Hydrolysis of Steroidal Esters Catalysed by Tetracyanoethylene
Tetracyanoethylene has been shown to be a mild catalyst which possesses some stereoselectivity, for the hydrolysis of the esters of steroidal alcohols.
Hanson, James R.,Uyanik, Cavit,Yildirim, Kudret
p. 580 - 581
(1998)
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Novel method for synthesizing cholesterol from 21-hydroxy-20-methylpregna-4-ene-3-ketone as raw material
The invention provides a method for synthesizing cholesterol from 21-hydroxy-20-methylpregna-4-ene-3-ketone (4-BA) as a raw material. The method comprises the step of: (1) carrying out etherification reaction, oxidation reaction, Grignard reagent addition reaction, sulfonylation reaction, reduction reaction, acetylation reaction and reduction reaction on 4-BA and triethyl orthoformate to obtain cholesterol. The synthesis method is simple in process, high in yield, low in cost, environment-friendly in process and suitable for industrial production.
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Paragraph 0039; 0047

(2021/11/19)

Method for synthesizing cholesterol by taking BA as raw material
The invention discloses a method for synthesizing cholesterol by taking BA as a raw material. A plant source raw material 21-hydroxy-20-methylpregna-4-en-3-one, also known as Shuangjiangchun or BA is taken as a raw material, and the cholesterol is synthesized by the steps of oxidation, Wittig reaction, acetylation, reduction, selective hydrogenation reduction and the like. The raw materials for synthesizing cholesterol are plant sources, the price is low, the safety is high, the risk of pathogenic bacteria and virus infection is avoided, and the synthesis method is easy to operate, high in yield, few in side reaction, environmentally friendly, good in economical efficiency and convenient for industrial production; and the invention solves the safety problem of the existing cholesterol product and the problems of high cost, environmental unfriendliness and unsuitability for large-scale industrial production in the synthesis technology.
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Paragraph 0113-0117

(2021/08/14)

Methods for preparing cholesterol, and derivatives and analogs thereof
The present invention relates to the field of pharmaceutical chemistry, and in particular to methods of preparing cholesterol,and derivatives and analogs thereof. The cholesterol derivatives include, but not limited to, 7-dehydrocholesterol, 25-hydroxycholesterol, 25- hydroxy7dehydrocholesterol and ergosterol. In the invention, phytosterol can be used as a raw material to prepare the compound shown in the formula I through microbial conversion, and then cholesterol and the derivatives and analogues thereof are prepared.
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Paragraph 0313-0314; 0321-0323

(2021/04/07)

Method for preparing cholesterol and derivatives thereof by taking phytosterol as raw material
The invention discloses a method for preparing cholesterol and derivatives thereof by taking phytosterol as a raw material. The preparation method comprises the following steps: taking phytosterol asa starting raw material, carrying out etherification protection on 3-hydroxyl of the phytosterol, and carrying out biological fermentation, oxidation, GM-2 oxidation, witting reaction, hydrogenation and hydrolysis to obtain cholesterol and derivatives thereof. According to the invention, sterols are developed and utilized, so that the problem of raw material sources is solved, and the environmental protection problem of waste water and waste residues is also solved.
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Paragraph 0065

(2021/02/20)

Me3SI-promoted chemoselective deacetylation: a general and mild protocol
A Me3SI-mediated simple and efficient protocol for the chemoselective deprotection of acetyl groups has been developedviaemploying KMnO4as an additive. This chemoselective deacetylation is amenable to a wide range of substrates, tolerating diverse and sensitive functional groups in carbohydrates, amino acids, natural products, heterocycles, and general scaffolds. The protocol is attractive because it uses an environmentally benign reagent system to perform quantitative and clean transformations under ambient conditions.
Gurawa, Aakanksha,Kashyap, Sudhir,Kumar, Manoj
p. 19310 - 19315
(2021/06/03)

PHOTOLYTIC COMPOUNDS AND TRIPLET-TRIPLET ANNIHILATION MEDIATED PHOTOLYSIS
The invention provides novel photolytic compounds and prodrugs, nanoparticles and compositions thereof, and methods of conducting photolysis mediated by triplet-triplet annihilation.
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Paragraph 0026

(2021/04/17)

KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
supporting information
p. 16702 - 16707
(2020/10/27)

Hafnium Triflate as a Highly Potent Catalyst for Regio- and Chemoselective Deprotection of Silyl Ethers
As a Group IVB transition metal Lewis acid, hafnium triflate [Hf(OTf) 4 ] exhibited exceptionally high potency in desilylations. Since the amounts of Hf(OTf) 4 required for the deprotection of 1°, 2°, 3° alkyl and aryl tert -butyldimethylsilyl (TBS) ethers are significantly different, ranging from 0.05 mol% to 3 mol%, regioselective deprotection of TBS could be easily implemented. Moreover, chemoselective cleavage of different silyl ethers or removal of TBS in the presence of most hydroxyl protecting groups was also accomplished. NMR analyses of silyl products from TBS deprotection indicated that Hf(OTf) 4 -catalyzed desilylation may proceed via different mechanisms, depending on the solvent used.
Zheng, Xiu-An,Kong, Rui,Huang, Hua-Shan,Wei, Jing-Ying,Chen, Ji-Zong,Gong, Shan-Shan,Sun, Qi
supporting information
p. 944 - 953
(2019/02/10)

Samarium(II) dibromide-promoted selective deprotection of a benzoyl protective group
The selective deprotection of a benzoyl group was very important methodology in the field of organic synthesis. Various methods for debenzoylation were investigated and developed in the past six decades, but more useful and selective strategies are now being strongly desired. In response to this strong demand, we developed the novel and selective deprotection of a benzoyl group by use of samarium(II) dibromide and a proton source. This deprotective reaction proceeded smoothly and the desired compound was obtained in good to excellent yields. In this paper, we will report the details of this deprotective reaction.
Yokoyama, Yasuo,Oyamada, Shun,Suzuki, Junya,Maruyama, Shou,Sakusabe, Takahiro,Suzuki, Shoko
supporting information
p. 1025 - 1032
(2018/03/23)

Purification method of cholesterol standard sample
The invention provides a purification method of a cholesterol standard sample. A derived and reduced cholesterol purification method is adopted; compared with a traditional recrystallization method, cholesterol obtained by the purification method has higher purity (greater than 99.6 percent) and better quality; the yield is also greatly improved and can reach 80 percent; furthermore, methyl tert-butyl ether for purifying is used for replacing ethyl ether under government control, which is used in the traditional recrystallization method, so that dangerousness in a production process is reduced.
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Paragraph 0041; 0042; 0043

(2017/10/28)

Novel method used for synthesizing cholesterol
The invention discloses a novel method used for synthesizing cholesterol. The novel method comprises following steps: 1, stigmasterol 02 is dissolved in an organic solvent I, and is subjected to silicon etherification reaction with trimethylchlorosilane under the effect of a catalyst, and a compound 03 is obtained via water washing and condensation; 2, the compound 03 is dissolved in an organic solvent II for ozone oxidation, zinc powder and acetate acid gracial are added for reduction, after reduction, filtering, washing, and condensation are carried out so as to obtain a compound 04; 3, triphenylphosphine is reacted with 1-halogenated-3-methyl butane so as to obtain 3-methyl butyl triphenyl halogenated phosphorus, the 3-methyl butyl triphenyl halogenated phosphorus is added into an aprotic solvent, a strong base is added, wittig reaction with a compound 4 is carried out, and neutralizing, condensation, and filtering are carried out so as to obtain a compound 05; 4, the compound 05 is subjected to selective hydrogenation in a solvent III under the action of a catalyst and a passivator, and filtering, condensation, and crystallization are carried out so as to obtain cholesterol 01. The novel method is simple; raw materials are cheap; the novel method is economic and is friendly to the environment, and is convenient for industrialized production.
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Paragraph 0021

(2017/08/29)

From organocatalysed desilylations to high-yielding benzylidenations of electron-deficient benzaldehydes
A new type of organoprecatalyst (MeSCH2Cl/KI) for desilylation and benzylidenation reactions has been designed. Both reactions are user friendly and high yielding (71->99%) and have fast reaction rates. The desilylation of iodo silyl ethers was achieved with no sequential etherification side reactions like those seen for reactions when using TBAF. In the application of the catalytic system to a 6-TBDMS ether of a glucoside, glucoside benzylidenations using electron-deficient benzaldehydes were achieved in 87% yield compared with the previously reported yields of 69-77%. Altogether, 14 benzylidenation reactions were realised using silyloxy alcohols and electrondeficient benzaldehydes instead of their activated acetal forms. In terms of reaction rates and yields, the order of the benzylidenations is p-fluorobenzaldehyde > benzaldehyde > p-anisaldehyde, and a possible mechanism is discussed. These experiments have preliminarily differentiated this cost-effective catalytic system from the classic Lewis acids.
Niu, Qun,Xing, Linlin,Li, Chunbao
p. 358 - 364
(2017/06/19)

Method for synthesizing cholesterol from stigmasterol
The invention relates to a method for synthesizing cholesterol from stigmasterol. The method specifically comprises the following steps: (1) enabling stigmasterol to react with benzene sulfonyl chloride so as to produce sulfonate, adding potassium acetate into sulfonate in methanol, and carrying out reflux reaction, so as to obtain a compound 03; (2) enabling the compound 03 to be subjected to oxidation reaction with ozone, and then, enabling the obtained reaction solution to react with zinc powder and glacial acetic acid, so as to obtain a compound 04; (3) enabling triphenylphosphine to react with 1-halo-3-methylbutane so as to obtain 3-methylbutyl triphenyl phosphonium halide, enabling 3-methylbutyl triphenyl phosphonium halide to react with a strong base so as to produce a wittig reagent, and enabling the wittig reagent to be subjected to wittig reaction with the compound 04, so as to obtain a compound 05; (4) enabling the compound 05 to be subjected to hydrogenation reaction in the presence of a catalyst, so as to obtain a compound 06; and (5) enabling the compound 06 to be subjected to hydrolysis reaction, thereby obtaining the cholesterol 01. According to the method, stigmasterol serves as a starting raw material and is cheap and readily-available, the process is simple, the amount of consumed raw and auxiliary materials is small, the yield is high, the cost is low, and the method is environment-friendly, so that industrial production is facilitated.
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Paragraph 0033; 0040

(2017/01/17)

Optimised conditions for the synthesis of 17O and 18O labelled cholesterol
Conditions are described for the preparation of cholesterol with 17O and 18O labels from i-cholesteryl methyl ether using minimal amounts of isotopically enriched water. Optimum yields employed trifluoromethanesulfonic acid as catalyst in 1,4-dioxane at room temperature with 5 equivalents of water. An isotopic enrichment >90% of that of the water used for the reaction could be attained. Tetrafluoroboric acid could also be used as catalyst, at the expense of a lower overall reaction yield. Byproducts from the reaction included dicholesteryl ether, methyl cholesteryl ether, compounds formed by ether hydrolysis, and olefins arising from elimination reactions. Reactions in tetrahydrofuran yielded significant amounts of cholesteryl ethers formed by reaction with alcohols arising from hydrolysis of the solvent.
De La Calle Arregui, Celia,Purdie, Jonathan A.,Haslam, Catherine A.,Law, Robert V.,Sanderson, John M.
p. 58 - 62
(2016/01/15)

Method for synthesizing cholesterol by using stigmasterol degradation products as raw materials
The invention provides a method for synthesizing cholesterol by using stigmasterol degradation products as raw materials. The method comprises the following steps: 1) performing an etherification reaction on 3-carbonyl-4-pregnene-22-aldehyde and triethyl orthoformate to obtain 3-ethyoxyl-3,5-pregnadiene-22-aldehyde; 2) preparing a 3-methylbutyltriphenyl phosphonium chloride solution; 3) adding potassium tert-butoxide into the 3-methylbutyltriphenyl phosphonium chloride solution, performing a wittig reaction on the 3-methylbutyltriphenyl phosphonium chloride solution and the 3-ethyoxyl-3,5-pregnadiene-22-aldehyde to obtain 3-ethyoxyl-3,5,22-triene cholestane; 4) catalyzing the 3-ethyoxyl-3,5,22-triene cholestane to perform a selective hydrogenation reaction to obtain 3-ethyoxyl-5-ene cholestane; 5) performing a reaction on the 3-ethyoxyl-5-ene cholestane and acetic anhydride to obtain 3-acetyl-5-ene cholestane; 6) performing a hydrolysis reaction on the 3-acetyl-5-ene cholestane to obtain the cholesterol. The synthesizing method is simple in process, and the mole yield of the cholesterol exceeds 85 percent by using the stigmasterol degradation products which are cheap and easily obtained as the raw materials; the production cost is low, the process is environmentally friendly, and the method is economical and environmentally friendly, and facilitates industrial implementation.
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Paragraph 0070; 0071

(2016/10/17)

Oxysterols: Synthesis and anti-leishmanial activities
Oxygenated sterols (2-16) were synthesized by skeletal rearrangement of steroidal allylic alcohols. All the derivatives were screened for their anti-leishmanial activities. Compounds 3, 11 and 12 showed potent activities. Compound 12 was found least toxic and induced highest nitric oxide (NO) at 48 h. Least toxicity of compound 12 on splenocytes validated its best anti-amastigote effect and induction of NO.
Ghosh, Pranab,Ghosh, Ashim,Mandal, Amitava,Sultana, Sirin Salma,Dey, Somaditya,Pal, Chiranjib
p. 65 - 73
(2016/03/04)

Development of an NH4Cl-Catalyzed Ethoxy Ethyl Deprotection in Flow for the Synthesis of Merestinib
An NH4Cl-catalyzed ethoxy ethyl deprotection was developed for the synthesis of merestinib, a MET inhibitor. Alternative reactor technologies using temperatures above the solvent boiling point are combined with this mild catalyst to promote the deprotection reaction. The reaction is optimized for flow and has been used to synthesize over 100 kg of the target compound. The generality of the reaction conditions is also demonstrated with other compounds and protecting groups.
Frederick, Michael O.,Calvin, Joel R.,Cope, Richard F.,Letourneau, Michael E.,Lorenz, Kurt T.,Johnson, Martin D.,Maloney, Todd D.,Pu, Yangwei John,Miller, Richard D.,Cziesla, Lauren E.
p. 1411 - 1417
(2015/11/02)

3α,5α-Cyclocholestan-6β-yl ethers as donors of the holesterol moiety for the electrochemical synthesis f cholesterol glycoconjugates
3α,5α-Cyclocholestan-6β-yl alkyl and aryl ethers were proved to be efficient cholesteryl donors in the electrochemical synthesis of glycoconjugates. 3α,5α-Cyclocholestan-6β-ol (i-cholesterol) and its tert-butyldimethylsilyl ether can also be used for this
Tomkiel, Aneta M.,Biedrzycki, Adam,Ploszyska, Jolanta,Narg, Dorota,Sobkowiak, Andrzej,Morzycki, Jacek W.
supporting information
p. 162 - 168
(2015/02/05)

Electrochemical synthesis of glycoconjugates from activated sterol derivatives
Several derivatives of cholesterol and other 3β-hydroxy- Δ5-steroids were prepared and tested as sterol donors in electrochemical reactions with sugar alcohols. The reactions afforded glycoconjugates with sugar linked to a steroid moiety by an ether bond. Readily available sterol diphenylphosphates yielding up to 54% of the desired glycoconjugate were found to be the best sterol donors.
Tomkiel, Aneta M.,Kowalski, Jan,P?oszyńska, Jolanta,Siergiejczyk, Leszek,?otowski, Zenon,Sobkowiak, Andrzej,Morzycki, Jacek W.
p. 60 - 67
(2014/03/21)

Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt as efficient mild polymeric solid acid catalyst
Aniline-terephthalaldehyde resin p-toluenesulfonic acid (ATRT) salt was easily prepared by the reaction of aniline with 1.25 equiv of terephthalaldehyde in the presence of 1.0 equiv of p-toluenesulfonic acid at 75 C for 24 h in EtOH. ATRT efficiently catalyzed the tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl (THP), triethylsilyl (TES), and tert-butyldimethylsilyl (TBDMS) ethers. Deprotection of dodecyl THP ether and dodecyl TBDMS ether catalyzed by ATRT proceeded faster than those by pyridinium p-toluenesulfonate (PPTS). ATRT was reused without significant loss of activities.
Tanemura, Kiyoshi,Suzuki, Tsuneo
supporting information
p. 6740 - 6743
(2013/11/19)

A convenient approach for the deprotection and scavenging of the PMB group using POCl3
A convenient and high yielding approach for the deprotection and scavenging of the p-methoxybenzyl (PMB) group in PMB ethers and PMB esters was developed using POCl3 as the reagent. 4-Methoxybenzyl chloride, a starting material used for the preparation of PMB ethers and esters was regenerated in the deprotection step. This mild and selective procedure tolerates several acid sensitive functional groups. The Royal Society of Chemistry 2013.
Ilangovan, Andivelu,Saravanakumar, Shanmugasundar,Malayappasamy, Subramani,Manickam, Govindaswamy
p. 14814 - 14828
(2013/09/02)

Electrochemical synthesis of glycoconjugates of 3β-hydroxy- Δ5-steroids by using non-activated sugars and steroidal thioethers
A new protocol for the electrochemical synthesis of glycoconjugates is presented. Thioether derivatives of cholesterol and other sterols were subjected to anodic oxidation in the presence of a sugar alcohol affording glycoconjugates with the sugar linked to a steroid moiety by an ether bond. The isomeric 6β-3α,5α-cyclo-steroidal thioethers proved to be better sterol donors than the normal 3β-Δ5-steroidal thioethers.
Tomkiel, Aneta M.,Brzezinski, Krzysztof,?otowski, Zenon,Siergiejczyk, Leszek,Wa?ejko, Piotr,Witkowski, Stanis?aw,Kowalski, Jan,P?oszyn?ska, Jolanta,Sobkowiak, Andrzej,Morzycki, Jacek W.
p. 8904 - 8913
(2013/09/23)

Silver(I)-Catalyzed deprotection of p -methoxybenzyl ethers: A mild and chemoselective method
The p-methoxybenzyl protecting group (PMB) on various alcohols and an acid was efficiently and selectively cleaved by the action of a catalytic amount of silver(I) hexafluoroantimonate combined with 0.5 equiv of 1,3,5- trimethoxybenzene in dichloromethane at 40 °C.
Kern, Nicolas,Dombray, Thomas,Blanc, Aurelien,Weibel, Jean-Marc,Pale, Patrick
p. 9227 - 9235,9
(2012/12/12)

Mild, selective deprotection of PMB ethers with triflic acid/1,3-dimethoxybenzene
An efficient method for the cleavage of the p-methoxybenzyl protecting group of several alcohols in the presence of 0.5 equiv of trifluoromethanesulfonic acid and 1,3-dimethoxybenzene in dichloromethane at room temperature is described.
Jung, Michael E.,Koch, Pierre
supporting information; experimental part
p. 6051 - 6054
(2011/11/28)

Simultaneously rapid deprotection of 3-acyloxy groups and reduction of D-ring ketones (nitrile) of steroids using DIBAL-H/NiCl2
An efficient preparation of hydroxysteroids by a one-pot, simultaneously rapid deprotection of 3-acyloxy groups and reduction of D-ring ketones (nitrile) of steroids using DIBAL-H in the presence of NiCl2 (10 mol %) is described. The attractive features of this procedure for the preparation of the hydroxysteroid derivatives are the mild reaction conditions, short reaction time, excellent yields, clean reaction profiles, and an inexpensive catalyst system.
Wang, Xingbin,Liu, Hui,Yan, Peiyun,Liu, Jinliang,Li, Yan,Sun, Qian,Wang, Cunde
experimental part
p. 291 - 293
(2011/10/05)

Preparation of fatty acid methyl esters for gas-liquid chromatography
A convenient method using commercial aqueous concentrated HCl (conc. HCl; 35%, w/w) as an acid catalyst was developed for preparation of fatty acid methyl esters (FAMEs) from sterol esters, triacylglycerols, phospholipids, and FFAs for gas-liquid chromatography (GC). An 8% (w/v) solution of HCl in methanol/water (85:15, v/v) was prepared by diluting 9.7 ml of conc. HCl with 41.5 ml of methanol. Toluene (0.2 ml), methanol (1.5 ml), and the 8% HCl solution (0.3 ml) were added sequentially to the lipid sample. The final HCl concentration was 1.2% (w/v). This solution (2 ml) was incubated at 45°C overnight or heated at 100°C for 1-1.5 h. The amount of FFA formed in the presence of water derived from conc. HCl was estimated to be 1.4%. The yields of FAMEs were ≥96% for the above lipid classes and were the same as or better than those obtained by saponification/methylation or by acid-catalyzed methanolysis/ methylation using commercial anhydrous HCl/ methanol. The method developed here could be successfully applied to fatty acid analysis of various lipid samples, including fish oils, vegetable oils, and blood lipids by GC. Copyright
Ichihara, Ken'Ichi,Fukubayashi, Yumeto
experimental part
p. 635 - 640
(2010/09/10)

A mild and efficient cleavage of tert-butyldimethylsilyl (TBS) and tetrahydropyranyl (THP) ethers using a catalytic amount of TBPA+ {radical dot} Sb Cl6-
A mild and efficient method for the deprotection of the TBS and THP ethers is described. A wide variety of TBS ethers as well as THP ethers can be easily deprotected to the corresponding parent hydroxyl compounds by employing a catalytic amount of tris(4-bromophenyl)aminium hexachloroantimonate (TBPA+ {radical dot} Sb Cl6-) in methanol at room temperature in good yield.
Xu, Yanfen,Tang, Shouchu,Han, Junjie,She, Xuegong,Pan, Xinfu
p. 3634 - 3637
(2008/09/19)

KHSO4-SiO2-MeOH An efficient selective solid-supported system for deprotection of alcohols from esters
KHSO4-SiO2 can efficiently deprotect alcohols from esters through transesterification in methanol under mild condition. Esters of aromatic alcohols are easily transesterified at room temperature compared to the corresponding aliphatic or alicyclic alcohol. NAcetyl compounds and ethers are resistant to the reagent under the above condition. The method is very useful for preparation of biodiesel methyl ricinoleate from castor oil.
Goswami, Amrit,Das, Ram N.,Borthakur, Naleen
p. 1893 - 1895
(2008/09/19)

Mild and chemoselective deacetylation method using a catalytic amount of acetyl chloride in methanol
Efficient deacetylation of alcohol acetates under mild acidic conditions was accomplished with a catalytic amount of acetyl chloride in methanol. Acetates of various primary, secondary, aromatic and sugar alcohols were successfully deprotected. Highly chemoselective removal of acetyl groups in presence of other commonly employed esters was also achieved in excellent yields. The reactivity of this transesterification-mediated deacetylation was found to be directly dependent upon the electronic and steric nature of the acetates. Georg Thieme Verlag Stuttgart.
Yeom, Chang-Eun,Lee, So Young,Kim, Young Jong,Kim, B. Moon
p. 1527 - 1530
(2007/10/03)

Efficient tetrahydropyranylation of alcohols and detetrahydropyranylation reactions in the presence of catalytic amount of trichloroisocyanuric acid (TCCA) as a safe, cheap industrial chemical
Preparation and cleavage of THP ethers of different hydroxy functional groups are easily and efficiently performed in the presence of trichloroisocyanuric acid (TCCA) in the absence of solvent with high yields.
Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
p. 3623 - 3630
(2007/10/03)

Facile Hydrolysis of Esters with KOH-Methanol at Ambient Temperature
A simple, rapid, and efficient method is reported for the hydrolysis of a variety of mono-and diesters of aromatic, aliphatic, fatty, and heterocyclic acids with potassium hydroxide in methanol at ambient temperature (～35°C).
Khurana, Jitender M.,Chauhan, Sushma,Bansal, Geeti
p. 83 - 87
(2007/10/03)

Tributylgermanium hydride as a replacement for tributyltin hydride in radical reactions
Tributylgermanium hydride (Bu3GeH) can be used as an alternative to tributyltin hydride (Bu3SnH) as a radical generating reagent with a wide range of radical substrates. Tributylgermanium hydride has several practical advantages over tributyltin hydride, e.g. low toxicity, good stability and much easier work-up of reactions. The reagent can be easily prepared in good yield and stored indefinitely. Suitable substrates include iodides, bromides, activated chlorides, phenyl selenides, tert-nitroalkanes, thiocarbonylimidazolides and Barton esters. Alkyl, vinyl and aryl radicals can be generated in radical reactions including reduction and cyclisation processes. Common radical initiators such as ACCN and triethylborane can be used. The slower rate of hydrogen abstraction by carbon-centred radicals from Bu 3GeH as compared to Bu3SnH facilitates improved cyclisation yields. Polarity reversal catalysis (PRC) with phenylthiol can be used in reactions which generate stable radical intermediates which will not abstract hydrogen from Bu3GeH.
Bowman, W. Russell,Krintel, Sussie L.,Schilling, Mark B.
p. 585 - 592
(2007/10/03)

Novel cationic amphiphiles
A cationic amphiphile for facilitating transport of a biologically active molecule into a cell has the structure A-F-D, in which A is a lipid anchor, D is a head group, and F is a spacer group having the structure described herein. A method for facilitating transport of a biologically active molecule into a cell comprises preparing a lipid mixture comprising a cationic amphiphile having structure A-F-D, preparing a lipoplex by contacting the lipid mixture with a biologically active molecule; and contacting the lipoplex with a cell, thereby facilitating transport of the biologically active molecule into the cell.
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Page/Page column 38, 8

(2010/02/06)

Facile removal strategy for allyl and allyloxycarbonyl protecting groups using solid-supported barbituric acid under palladium catalysis
Solid-supported barbituric acid can be used for the palladium(0)-catalyzed deprotection of allyl amines, carbamates, carbonates, esters and ethers. This solid-supported reagent facilitates isolation and purification of the deprotected compounds, especially acids and amines.
Tsukamoto, Hirokazu,Suzuki, Takamichi,Kondo, Yoshinori
p. 1105 - 1108
(2007/10/03)

Deprotection of benzyl and p-methoxybenzyl ethers by chlorosulfonyl isocyanate-sodium hydroxide
CSI-NaOH procedure provided a new and mild methodology for the deprotection of benzyl and p-methoxybenzyl ethers without affecting the other functional groups under similar reaction conditions.
Kim, Ji Duck,Han, Gyoonhee,Zee, Ok Pyo,Jung, Young Hoon
p. 733 - 735
(2007/10/03)

Facile and selective cleavage of allyl ethers based on palladium(0)-catalyzed allylic alkylation of N,N′-dimethylbarbituric acid
The classical palladium(0)-catalyzed allylic alkylation of N,N′-dimethylbarbituric acid can be applied to the facile and selective cleavage of allylic alkyl ethers to release the corresponding alcohols in excellent yield. This reaction proceeds under neutral conditions without any additive to activate the allyl ethers and tolerates various functional groups, such as ester, ether, ketone, alkyl and aryl chloride, nitrile and nitro groups.
Tsukamoto, Hirokazu,Kondo, Yoshinori
p. 1061 - 1063
(2007/10/03)

p-Methoxybenzyl ether cleavage by polymer-supported sulfonamides.
[reaction: see text] p-Methoxybenzyl ethers have been found to transfer from alcohols to sulfonamides in the presence of catalytic trifluoromethanesulfonic acid. This process for protecting group removal can be performed in solution with yields >94%. Through the use of sulfonamide-functionalized ("safety-catch") resins, p-methoxybenzyl ethers can be cleaved in excellent yields with minimal purification.
Hinklin, Ronald J,Kiessling, Laura L
p. 1131 - 1133
(2007/10/03)

Cleavage of a p-cyanobenzyl group from protected alcohols, amines, and thiols using triethylgermyl sodium
Alcohols, amines, and thiols protected with a p-cyanobenzyl group can be easily and quantitatively deprotected using triethylgermyl sodium under mild conditions.
Yokohama, Yasuo,Takizawa, Shuichi,Nanjo, Masato,Mochida, Kunio
p. 1032 - 1033
(2007/10/03)

Acetonyltriphenylphosphonium bromide and its polymer-supported analogues as catalysts in protection and deprotection of alcohols as alkyl vinyl ethers
Both acetonyltriphenylphosphonium bromide (ATPB, 1) and poly-p-styryldiphenylacetonylphosphonium bromide (A) were effective catalysts in the protection of alcohols as THP, THF, and EE ethers as well as the cleavage of THP, THF, and EE ethers to the corresponding alcohols. They could be applied to 1°, 2° and 3° alcohols, phenol and acid-labile alcohols. Both ATPB and catalyst A are excellent catalysts in the present study. It needed only 1×10-2-1.25×10-2 mol equiv. of the polymer-supported catalyst A in the reactions.
Hon, Yung-Son,Lee, Chia-Fu,Chen, Rong-Jiunn,Szu, Ping-Hui
p. 5991 - 6001
(2007/10/03)

Synthesis of solid-phase bound sulfonate esters
p-Pivaloyloxybenzenesulfonyl and methylsulfonyl residues were used as linkers to attach secondary alcohols to Wang resin and to Merrifield resin, respectively. p-Pivaloyloxybenzenesulfonates of alcohols were deprotected at the phenolic group and coupled with Wang resin by Mitsunobu reaction whereas mesylates were lithiated at the methyl group and subsequently connected with chloromethyl residues of Merrifield resin.
Furman,Lysek,Matyjasek,Wojtkielewicz,Chmielewski
p. 2795 - 2802
(2007/10/03)

Undesirable deprotection of O-TBDMS groups by Pd/C-catalyzed hydrogenation and chemoselective hydrogenation using a Pd/C(en) catalyst
In general, O-TBDMS protective groups have been believed to be stable toward Pd/C-catalyzed hydrogenation conditions. In practice, however, frequent and unexpected loss of the TBDMS protective group of a variety of hydroxyl functions occurred under neutral and mild hydrogenation conditions using 10% Pd/C in MeOH. When a 10% Pd/C-ethylenediamine complex catalyst [10% Pd/C(en)] was used instead of 10% Pd/C, the undesirable problem was perfectly overcome and the chemoselective hydrogenation of reducible functionalities leaving intact the TBDMS protective group was achieved.
Hattori, Kazuyuki,Sajiki, Hironao,Hirota, Kosaku
p. 2109 - 2114
(2007/10/03)

Water accelerated Sm/TMSCl reductive system: Debromination of vic- dibromides and reduction of sodium alkyl thiosulfates
A simple and efficient method for the debromination of vic-dibromides to (E)-alkenes and reduction of sodium alkyl thiosulfates to disulfides promoted by Sm/TMSCl/H2O (trace) has been described.
Xu, Xiaoliang,Lu, Ping,Zhang, Yongmin
p. 1917 - 1925
(2007/10/03)

A new efficient commercial iron mediated debromination of aryl substituted vic-dibromide
Debromination of vic-dibromides with commercially available metallic iron in a methanolic medium affords alkenes and alkynes in excellent yields.
Thakur, Ashim J.,Boruah, Anima,Baruah, Bipul,Sandhu, Jagir S.
p. 157 - 162
(2007/10/03)

Mn(OAc)3 - An efficient oxidant for regeneration of DDQ: Deprotection of p-methoxy benzyl ethers
Mn(OAc)3 has been successfully developed as a new oxidant for the regeneration of DDQ from HDDQ. This DDQ regeneration technique, making use of 3 equiv. of Mn(OAc)3-DDQ (10 mol%), was applied to the deprotection of p-methoxy benzyl (PMB) ethers. (C) 2000 Elsevier Science Ltd.
Sharma,Lavanya,Mahalingam,Krishna, Palakodety Radha
p. 10323 - 10326
(2007/10/03)

A new mild PTSA-catalyzed method for sulfate ester hydrolysis and acid-catalyzed rearrangement of 12-acetyl-diene-11-ol tetracyclic triterpenoids involving an angular methyl migration
Tetracyclic triterpenoids containing the 12-acetyl-Δ8,14-diene-ll-ol moiety undergo a series of acid-catalyzed rearrangements. The rearrangement products have been characterized, plausible mechanisms for the rearrangement have been elucidated and conditions have been developed to give high yields of the rearrangement products. A new and general PTSA·H2O and PPTS-catalyzed sulfate hydrolysis method has been developed. (C) 2000 Elsevier Science Ltd.
Singh
p. 6973 - 6976
(2007/10/03)

Tetrabutylammonium tribromide (TBATB) - MeOH: An efficient chemoselective reagent for the cleavage of tert-butyldimethylsilyl (TBDMS) ethers
(equation presented) R = H, alkyl or aryl P = TBDMS, TBDPS, THP, DMT TBDMS THP and DMT ethers are efficiently deprotected with tetrabutylammonium tribromide in methanol. The apparent order of stability of different protecting group is phenolic TBDMS > 1° OTBDPS > 2° OTBDMS > 2° OTHP > 1° OTHP > 1° OTBDMS > 1° ODMT. TBDMS ether has been cleaved selectively in the presence of isopropylidine, Bn, Ac, Bz, THP, and TBDPS groups. This method is high yielding, fast, clean, safe, cost-effective, and therefore most suitable for practical organic synthesis.
Gopinath, Rangam,Patel, Bhisma K.
p. 4177 - 4180
(2007/10/03)

Mechanism of the second methylation in sitosterol side-chain biosynthesis in higher plants: Metabolic fate of 28-hydrogens of 24- methylenecholesterol in Morus alba cell cultures
Biosynthesis of the side-chain of sitosterol in higher plants involves two methylation steps by attack of S-adenosylmethionine. The stereochemical features of the second methylation, namely, of the conversion from 24- methylenecholesterol to isofucosterol in higher plants has been investigated. Feeding studies of synthesized [28E-2H]- and [28Z-2H]-24- methylenecholesterols to cultured cells of Morus alba followed by 2H NMR analysis of the resulting isofucosterol established that the second methylation proceeded in such a manner that addition of the methyl group and proton loss occur on opposite faces of the original Δ(24(28))-double bond. (C) 2000 Elsevier Science Ltd.
Okuzumi, Tatsuya,Kaji, Yuko,Hamada, Hiroki,Fujimoto, Yoshinori
p. 3623 - 3626
(2007/10/03)

Copper(II) chloride dihydrate: A catalytic agent for the deprotection of tetrahydropyranyl ethers (THP ethers) and 1-ethoxyethyl ethers (EE ethers)
Tetrahydropyranyl ethers (THP groups) and 1-ethoxyethyl ethers (EE groups) are removed upon refluxing in 95% EtOH or Me2CO-H2O (95:5) in the presence of a catalytic amount of copper(II) chloride dihydrate (2-5 mol%).
Wang, Jianbo,Zhang, Chao,Qu, Zhaohui,Hou, Yihua,Chen, Bei,Wu, Peng
p. 294 - 295
(2007/10/03)

Montmorillonite clays catalysis IX: A mild and efficient method for removal of tetrahydropyranyl ethers
A variety of tetrahydropyranyl ethers of alcohols and phenols are easily removed in the presence of catalytic of amount of montmorillonite clays in methanol at 40-50 °C in excellent yield.
Li, Tong-Shuang,Zhang, Zhan-Hui,Jin, Tong-Shou
p. 181 - 188
(2007/10/03)