- Formation of hemiacetal esters in lipase-catalysed reactions of vinyl esters with hindered secondary alcohols
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Normally many lipases are efficient catalysts for the acetylation of alcohols with vinyl acetate. Unexpectedly, we found that some sterically hindered secondary alcohols react slowly to yield hemiacetal esters as mixtures of diastereomers. Their formation can be explained by the reaction of the alcohol with acetaldehyde that is produced by the lipase-catalysed splitting of vinyl acetate and subsequent acetylation of the resulting hemiacetal by the lipase. (C) 2000 Elsevier Science Ltd.
- H?gberg, Hans-Erik,Lindmark, Marica,Isaksson, Dan,Sj?din, Kristina,Franssen, Maurice C. R.,Jongejan, Hugo,Wijnberg, Joannes B. P. A.,De Groot, Aede
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Read Online
- Method for synthesizing bornyl acetate from turpentine
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The invention discloses a method for synthesizing bornyl acetate from turpentine, which relates to the technical field of deep processing of turpentine. The preparation method comprises the followingsteps of proportioning titanium sulfate and hydroxycarboxylic acid to form a composite catalyst, mixing turpentine, acetic acid and the composite catalyst, and reacting in a stirring state, after thereaction is finished, filtering, and removing acetic acid from the filtrate to obtain a solution containing bornyl acetate, neutralizing the solution containing the bornyl acetate, and washing with water to obtain a bornyl acetate crude product, and then fractionating the crude product of the bornyl acetate to obtain the bornyl acetate. The synthesis method provided by the invention is high in catalytic activity, low in cost and high in selectivity on the borneol acetate, and does not need to use a raw material with too high pinene content.
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Paragraph 0036-0280
(2021/01/29)
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- Simple Plug-In Synthetic Step for the Synthesis of (?)-Camphor from Renewable Starting Materials
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Racemic camphor and isoborneol are readily available as industrial side products, whereas (1R)-camphor is available from natural sources. Optically pure (1S)-camphor, however, is much more difficult to obtain. The synthesis of racemic camphor from α-pinene proceeds via an intermediary racemic isobornyl ester, which is then hydrolyzed and oxidized to give camphor. We reasoned that enantioselective hydrolysis of isobornyl esters would give facile access to optically pure isoborneol and camphor isomers, respectively. While screening of a set of commercial lipases and esterases in the kinetic resolution of racemic monoterpenols did not lead to the identification of any enantioselective enzymes, the cephalosporin Esterase B from Burkholderia gladioli (EstB) and Esterase C (EstC) from Rhodococcus rhodochrous showed outstanding enantioselectivity (E>100) towards the butyryl esters of isoborneol, borneol and fenchol. The enantioselectivity was higher with increasing chain length of the acyl moiety of the substrate. The kinetic resolution of isobornyl butyrate can be easily integrated into the production of camphor from α-pinene and thus allows the facile synthesis of optically pure monoterpenols from a renewable side-product.
- Calderini, Elia,Drienovská, Ivana,Myrtollari, Kamela,Pressnig, Michaela,Sieber, Volker,Schwab, Helmut,Hofer, Michael,Kourist, Robert
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p. 2951 - 2956
(2021/06/18)
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- Synthesis and characterization of a new acid molten salt and the study of its thermal behavior and catalytic activity in Fischer esterification
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A new acid molten salt was prepared and its structure elucidation was conducted by FTIR, 1D NMR, 2D NMR, and mass spectrometry. Further support to elucidate the chemical structure of the 1H,4H-piperazine-N,N′-diium ring of the new acid molten salt was achieved by1H and13C NMR, and COSY analyses of 1H,4H-piperazine-N,N′-diium dibromide, which is synthesized and characterized for the first time in the current work. The analysis of FTIR and NMR spectra as well as pH and titrimetric analysis excluded the formation of [SO4]2?and the presence of an excess of H2SO4. Moreover, no distinguishing peak was detected for the acid proton of [HSO4]?in DMSO-d6. The thermal phase transition and thermal stability of the acid molten salt were also recorded, which approved the strong interaction between a dication and hydrogen sulfate anions. According to the acidity of the new molten salt, we encourage the study of its catalytic activity for the acetylation ofn-pentanol using glacial acetic acid. Pentyl acetate was obtained in 89.0% conversion and 78.0% isolated yield. The1H NMR spectrum of the residue showed an excess of HOAc together with molten salt, whereas the1H NMR spectrum of the upper phase exhibited pure pentyl acetate. After separation of the upper phase, the residue was concentrated and used in the next run without further purification. No significant changes in the chemical structure and catalytic activity of the new molten salt were observed even after the 5th run. Two chiral alcohols, including (?)-menthol and (+)-borneol, as well as α-tocopherol (α-TCP) were also acetylated with acetic acid in the presence of the new acid molten salt under optimized reaction conditions, which afforded the desired acetates in high yields.
- Zaharani, Lia,Khaligh, Nader Ghaffari,Johan, Mohd Rafie,Gorjian, Hayedeh
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p. 7081 - 7088
(2021/05/03)
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- Synthesis, Characterisation, and Determination of Physical Properties of New Two-Protonic Acid Ionic Liquid and its Catalytic Application in the Esterification
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A new ionic liquid was synthesised, and its chemical structure was elucidated by FT-IR, 1D NMR, 2D NMR, and mass analyses. Some physical properties, thermal behaviour, and thermal stability of this ionic liquid were investigated. The formation of a two-protonic acid salt namely 4,4′-trimethylene-N,N′-dipiperidinium sulfate instead of 4,4′-trimethylene-N,N′-dipiperidinium hydrogensulfate was evidenced by NMR analyses. The catalytic activity of this ionic liquid was demonstrated in the esterification reaction of n-butanol and glacial acetic acid under different conditions. The desired acetate was obtained in 62-88 % yield without using a Dean-Stark apparatus under optimal conditions of 10 mol-% of the ionic liquid, an alcohol to glacial acetic acid mole ratio of 1.3: 1.0, a temperature of 75-100°C, and a reaction time of 4 h. α-Tocopherol (α-TCP), a highly efficient form of vitamin E, was also treated with glacial acetic acid in the presence of the ionic liquid, and O-acetyl-α-tocopherol (Ac-TCP) was obtained in 88.4 % yield. The separation of esters was conducted during workup without the utilisation of high-cost column chromatography. The residue and ionic liquid were used in subsequent runs after the extraction of desired products. The ionic liquid exhibited high catalytic activity even after five runs with no significant change in its chemical structure and catalytic efficiency.
- Shahnavaz, Zohreh,Zaharani, Lia,Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie
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p. 165 - 172
(2020/10/26)
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- Heterogeneous zeolite-based catalyst for esterification of α-pinene to α-terpinyl acetate
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The purpose of this study is to determine the most effective type of heterogeneous catalyst such as natural zeolite (ZA), Zr-natural zeolite (Zr/ZA) and zeolite Y (H/ZY) in esterification of α-pinene. α-terpinyl acetate was successfully synthesized from α-pinene and acetic anhydride by their heterogeneous catalysts. The esterification reaction was carried out with reaction time, temperature and zeolite catalysts. The most effective catalysts used in the synthesis of α-terpinyl acetate is catalyst H/ZY with the yield is 52.83% at 40oC for the time 4 h with a selectivity of 61.38%. The results showed that the effective separation of catalyst could contribute to developing a new strategy for the synthesis of α-terpinyl acetate.
- Wijayati, Nanik,Kusumastuti, Ella,Alighiri, Dante,Rohmawati, Baiti,Lusiana, Retno Ariadi
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p. 399 - 403
(2019/06/05)
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- 4-Imidazol-1-yl-butane-1-sulfonic acid ionic liquid: Synthesis, structural analysis, physical properties and catalytic application as dual solvent-catalyst
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4-Imidazol-1-yl-butane-1-sulfonic acid (ImBu-SO3H) has been successfully synthetized and fully characterized by FT-IR and high-resolution NMR spectroscopy (1H, 13C). The “plausible” alternative structures of ImBu-SO3H were discussed on the basis of its NMR data. The ionic liquid showed interesting dual solvent-catalyst property, which was studied experimentally for the acetylation of a variety of functionalized alcohols, phenols, thiols, amines and α-tocopherol (α-CTP) as the most active form of vitamin E with acetic anhydride and which provided good yields within a short reaction time. ImBu-SO3H was successfully recycled by product extraction with an average recovered yield of 82% for 5 subsequent runs. The catalytic activity of the recycled ImBu-SO3H showed almost no loss even after five consecutive runs.
- Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie,Juan, Joon Ching
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p. 866 - 878
(2019/07/12)
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- Method for synthesizing isobornyl acetate by camphene
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The invention discloses a method for synthesizing isobornyl acetate by camphene. The method comprises the following steps of adding camphene, glacial acetic acid, a main catalyst (hydroxycarboxylic acid) and an additive into a reaction kettle according to a mass ratio of 100:(20 to 400):(1 to 50):(1 to 20), starting to stir, controlling the temperature to 40 to 100 DEG C, and reacting for 2 to 24h, so as to obtain a synthesized product; adding a small amount of water into the synthesized product, standing and delaminating, wherein the upper oil layer is a target product containing isobornyl acetate, the lower layer is acid water containing the catalyst and acetic acid, and the acid water is dewatered and recycled; adding the target product into a water washing tank, adding alkaline water to neutralize, and then adding water to wash, so as to obtain a crude product of the isobornyl acetate; relieving pressure and distilling, so as to obtain the refined isobornyl acetate. The method forsynthesizing the isobornyl acetate by catalyzing the camphene has the advantages that the obtained product has high yield and high purity, and is easy to separate; the used catalyst has high catalyzing activity; the preparation is simple, the repeatability is good, the toxicity is avoided, the corrosion property is low, the isobornyl acetate belongs to regeneration resources, and the industrialization product is easy.
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Page/Page column 5-13
(2018/12/13)
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- Rice husk ash: A new, cheap, efficient, and reusable reagent for the protection of alcohols, phenols, amines, and thiols
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Amild, efficient, and eco-friendly protocol for the protection of alcohols and phenols as trimethylsilyl ethers has been developed using rice husk ash as a reagent. This reagent is also able to catalyze the acetylation of alcohols, phenols, thiols, and amines with acetic anhydride. All reactions were performed under mild conditions in good to high yields. Copyright
- Shirini,Akbari-Dadamahaleh, Somayeh,Mohammad-Khah, Ali
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p. 577 - 586
(2014/06/09)
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- Iron(III) tosylate catalyzed acylation of alcohols, phenols, and aldehydes
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Iron(III) p-toluenesulfonate (tosylate) is an efficient catalyst for acetylation of alcohols, phenols, and aldehydes. The acetylation of 1° and 2° alcohols, diols, and phenols proceeded smoothly with 2.0 mol % of catalyst. However, the reaction worked well with only a few 3° alcohols. The methodology was also applicable to the synthesis of a few benzoate esters but required the use of 5.0 mol % catalyst. Aldehydes could also be converted into the corresponding 1,1-diesters (acylals) under the reaction conditions. Iron(III) tosylate is an inexpensive, and easy to handle, commercially available catalyst.
- Baldwin, Neil J.,Nord, Anna N.,O'Donnell, Brendan D.,Mohan, Ram S.
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p. 6946 - 6949
(2013/01/15)
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- Liquid phase acetoxylation of α-pinene over Amberlyst-70 ion-exchange resin
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Heterogeneously-catalyzed and solvent-catalyzed liquid phase acetoxylation of α-pinene with acetic acid acting as both a solvent and a reagent was studied. Both solvent-catalyzed and catalytic experiments were carried out and various reaction conditions were studied. The influence of temperature, pressure, solvent and gas milieu were taken into account. Bornyl, fenchyl, verbenyl as well as α-terpinyl acetates, limonene, camphene and γ-terpinene were found among reaction products. The addition of the catalyst allowed for maximization of the yield of bornyl acetate. The predominant products obtained were α-terpinyl, verbenyl and bornyl acetates. The reaction pathways were identified and evaluated. The aim of this work was to study the feasibility of batch acetoxylation of α-pinene. The analysis of the complex product distribution is not trivial and, consequently, resolving the reaction network was important. The optimized reaction conditions were searched for aiming at an efficient conversion of α-pinene to a mixture of valuable products.
- Golets,Ajaikumar,Blomberg,Grundberg,W?rn?,Salmi,Mikkola
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scheme or table
p. 43 - 50
(2012/10/18)
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- Microwave-assisted α-pinene acidic catalytic isomerisation
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A comparative study of microwave assisted α-pinene acidic catalytic isomerisation reactions with near-critical water procedure under microwave irradiation is presented. This study can be performed because in both cases the mechanism is similar, namely an acidiccatalyzed rearrangement. The non-critical method technique is milder using a lower temperature and pressure and a shorter reaction time than near-critical water conditions. The general aspect of the selectivity of the reaction products is changed, being higher for α-terpinolene and γ-terpinolene and lower for limonene and camphene compared to the non-critical conditions.
- Szuecs-Balazs, Jozsef Zsolt,Coros, Maria,Molnar, Diana,Vlassa, Mircea
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p. 209 - 213
(2013/03/13)
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- Preparation, characterization and use of poly(4-vinylpyridinium) perchlorate as a new, efficient, and versatile solid phase catalyst for acetylation of alcohols, phenols and amines
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Poly(4-vinylpyridine) perchlorate, is a supported, recyclable, eco-benign catalyst for the reaction acetylation of structurally diverse alcohols, phenols and amines at room temperature under solvent-free conditions. The catalyst was studied by FT-IR, X-ray diffraction, Scanning Electron Microscope and Thermo-gravimetric Analyses. All the products were extensively characterized by 1H NMR, FT-IR, GC-MS and melting point analyses. The catalyst can be recovered and reused without loss of activity. The work-up of the reaction consists of a simple filtration, followed by concentration of the crude product and purification. It is important to point out that a large-scale reaction is possible using a same amount of catalyst.
- Khaligh, Nader Ghaffari
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- A mild and efficient method for the methoxymethylation and acetylation of alcohols promoted by benzyltriphenylphosphonium tribromide
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A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
- Shirini, Farhad,Imanzadeh, Gholam Hossein,Mousazadeh, Seyyed Ali Reza,Mohammadpoor-Baltork, Iraj,Abedin, Masoumeh
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experimental part
p. 1187 - 1190
(2011/10/05)
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- Samarium trifluoromethanesulfonate: An efficient moisture tolerant acylation catalyst under solvent-free condition
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Samarium trifluoromethanesulfonate catalyzed the acylation of phenols, alcohols, thiols, free reducing sugars, and glycosides in excellent yields at ambient temperature under solvent-free condition using stoichiometric amounts of various anhydrides. (Chemical Equation Presented). Copyright Taylor & Francis Group, LLC.
- Roy, Bimalendu,Dasgupta, Somnath,Kumar Rajput, Vishal,Mukhopadhyay, Balaram
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- Cl3CCONH2/PPh3: A versatile reagent for synthesis of esters
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Cl3CCONH2/PPh3 was a versatile reagent to convert carboxylic acids into their corresponding acid chlorides. This intermediate was clearly confirmed by spectroscopic methods (IR, 1H, 13C NMR). This one-pot reaction of in situ acid chloride generated with various alcohols successfully furnished the corresponding esters in moderate to excellent yields. Copyright ? Taylor & Francis Group, LLC.
- Chantarasriwong, Oraphin,Jang, Doo Ok,Chavasiri, Warinthorn
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scheme or table
p. 2845 - 2856
(2009/04/11)
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- A highly selective, high-speed, and hydrolysis-free O-acylation in subcritical water in the absence of a catalyst
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(Chemical Equation Presented) Fast and furious: A wide range of alcohols are acylated by acetic anhydride, in the absence of catalyst, in subcritical water in a flow-type microreaction system. The esters are selectively produced in high yields at temperatures of 200 to 250°C. Varying the amount of acetic anhydride added with respect to the alcohols allows the regioselective acylation of one or both hydroxy groups of various dihydroxy compounds (see picture).
- Sato, Masahiro,Matsushima, Keiichiro,Kawanami, Hajime,Ikuhsima, Yutaka
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p. 6284 - 6288
(2008/04/05)
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- N, O-ligand accelerated zinc-catalyzed transesterification of alcohols with vinyl esters
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N-Phenyldiethanolamine (1f) is an efficient ligand for zinc-catalyzed transesterification of alcohols with vinyl acetate (R3 = Me) at room temperature. In the case of using other vinyl esters (R3 = Et, n-Pr, Ph), the corresponding products were easily obtained in the presence of pyridine-type ligand 2 instead of aminoalcohol 1f.
- Mino, Takashi,Hasegawa, Tae,Shirae, Yoshiaki,Sakamoto, Masami,Fujita, Tsutomu
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p. 4389 - 4396
(2008/02/13)
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- Lithium perchlorate catalyzed acetylation of alcohols under mild reaction conditions
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Lithium perchlorate is found to efficiently catalyze the acetylation of alcohols and phenols with acetic anhydride in good to excellent yields.
- Nakae,Kusaki,Sato
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p. 1584 - 1586
(2007/10/03)
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- P(RNCH2CH2)3N: Efficient catalysts for transesterifications, acylations, and deacylations
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Extremely strong nonionic superbases of the type P(RNCH2CH2)3N catalyze the transesterification of carboxylic acid esters with high selectivity and yields at 25 °C. These bases also catalyze the deacetylation of alcohols under mild conditions in quantitative yields. Using enol acetates as acylating agents, primary and secondary alcohols are efficiently protected as acetates through the action of these catalysts. Substituents such as epoxide, carbamate, acetal, oxazoline, nitro, and alkynyl functionalities are tolerated under the reaction conditions. N-Protected peptides undergo clean transesterification without significant racemization, making this methodology potentially very useful.
- Ilankumaran, Palanichamy,Verkade
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p. 3086 - 3089
(2007/10/03)
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- Steric Structure of Mono- and Bicyclic Terpene Derivatives as Determined by NMR Spectroscopy
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The 1H and 13C NMR spectral data for a series of newly prepared mono- and bicyclic terpene derivatives are presented. The feasibility of NMR spectroscopy for examining cis-trans isomerism in terpenes and E-Z isomerism in oximes is discussed. From the values of vicinal spin-spin coupling constants, the signal multiplicities, and the appearance of W-interaction in the 1H spectra the steric orientation of the substituents in the complex structures of p-menthane, pinane, carane, and norbornane derivatives are unambiguously assigned. The steric structure of derivatives with a tetracoordinated carbon atom, where the characteristic spin-spin coupling constants are absent, can be correctly determined from 13C NMR spectral data.
- Koval'skaya,Kozlov
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p. 306 - 315
(2007/10/03)
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- Stomachic principles in ginger. III. An anti-ulcer principle, 6- gingesulfonic acid, and three monoacyldigalactosylglycerols, gingerglycolipids A, B, and C, from Zingiberis Rhizoma originating in Taiwan
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An anti-ulcer constituent, 6-gingesulfonic acid, and three monoacyldigalactosylglycerols, gingerglycolipids A, B, and C, were isolated from Zingiberis Rhizoma, the dried rhizome of Zingiber officinale ROSCOE which was cultivated in Taiwan, together with (+)-angelicoidenol-2-O-β-D- glucopyranoside. Based on chemical reactions and physicochemical evidence, the structures of 6-gingesulfonic acid, gingerglycolipids A, B, and C have been determined. In addition, the absolute stereostructure of (+)- angelicoidenol-2-O-β-D-glucopyranoside was clarified on the basis of its synthesis from d-borneol. 6-Gingesulfonic acid showed weaker pungency and more potent anti-ulcer activity than 6-gingerol and 6-shogaol.
- Yoshikawa,Yamaguchi,Kunimi,Matsuda,Okuno,Yamahara,Murakami
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p. 1226 - 1230
(2007/10/02)
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- Synthesis and Absolute Configuration of the Antiparasitic Furanosesquiterpenes (-)-Furodysin and (-)-Furodysinin. Camphor as a Six-Membered Ring Chiral Pool Template
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The syntheses of (-)-furodysin ((-2)-2a) and (-)-furodysinin ((-)-3a) in four steps starting from (+)-9-bromocamphor (18) has been accomplished, thus establishing the absolute configuration of these and related metabolites.This was made possible by the unexpected exo selectivity in the aldol condensation of camphor-like enolates with aldehydes.This has been found to be a general phenomenon in the camphor system.Further, anionic fragmentation of the C1-C7 bond of camphor derivatives has allowed access to synthetic intermediates containing functionalized six-memberedrings, thus opening up avenues from camphor to a new class of chiral pool elements not currently available from chiral pool substances.
- Vaillancourt, Valerie,Agharahimi, Mohamad R.,Sundram, Uma N.,Richou, Olivier,Faulkner, D. John,Albizati, Kim F.
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p. 378 - 387
(2007/10/02)
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- ENANTIOSELECTIVITY IN THE HYDROLYSIS OF BICYCLIC MONOTERPENE ACETATES WITH THE CULTURED CELLS OF NICOTIANA TABACUM
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Key Word Index - Nicotiana tabacum; Solanaceae; tissue culture; biotransformation; hydrolysis; enantioselectivity; bicyclic monoterpene acetates.The enantioselectivity in the hydrolysis of bornyl acetate; isobornyl acetate and isopinocampheyl acetate with the cultured cells of Nicotiana tabacum was investigated.The cultured cells were found to have the ability to hydrolyse enantioselectively the acetates, of which the configuration at the carbon atom bearing the acetoxyl group is R.
- Suga, Takayuki,Hirata, Toshifumi,Izumi, Shunsuke
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p. 2791 - 2792
(2007/10/02)
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- The endo- and exo-1,7,7-Trimethylbicyclo-heptan-2-amines (Bornan-2-amines) and Their Acetamides
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Melting points provide a poor method for differentiation between the exo and endo N-(bornan-2-yl)-acetamides, and have led to errors by previous workers.Spectral differences leading to unambiguous assignment are discussed in this paper.Trapping of the bornan-2-yl carbenium ion with acetonitrile leads to exo products.
- Carman, Raymond M.,Greenfield, Kay L.
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p. 1785 - 1790
(2007/10/02)
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- Rearrangement of Pinane Derivatives. Part 8. Deamination of 2αH-Pinan-3α-ylamine
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Solvolysis of 2αH-pinan-3α-yl toluene-p-sulphonate has been shown to proceed with concomitant 1,2-hydride shift to give the pinan-2-yl carbocation.Contrary to earlier reports, this species reacts normally to give, in good yield, pinan-2-yl substitution products.In contrast the pinan-3-ylamines react via a similar route, but give much smaller amounts of pinan-2-yl products.The usual reasons for differences between solvolysis and deamination (i.e. the intermediacy of diazonium ions and/or high-energy ions) can be discounted, and possible reasons for the differences in behaviour are discussed.
- Giddings, Rodney M.,Jones-Parry, Richard,Salmon, J. Roger,Whittaker, David
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p. 725 - 728
(2007/10/02)
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- Electronic Effects of Polar Substituents in the Gas Phase Unimolecular Elimination of 4-Substituted Isobornyl Acetates
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The rates of gas-phase elimination of a series of 4-substituted isobornyl acetates have been measured in the presence of propene between 209-370 deg C and within a pressure range 37-153 Torr; a static system with seasoned vessels was used.The reaction are unimolecular, homogeneous, and obey a first-order rate law; electron-withdrawing substituents at C(4) cause a diminution in the elimination rate, such that ρ1 -0.69 in a Hammett treatment.The temperature dependence of the rate coefficients is illustrated for the Arrhenius equation for isobornyl acetate: logk/s-1=(12.82+/-0.13)-(189.2+/-1.5)kJmol-1/2.303RT.The results are consistent with a cyclic transition state in which C(2)-O cleavage is more advanced than that of C(3)-H.The major primary product of elimination of isobornyl acetate is bornylene, which partially isomerises to camphene and tricyclene under the reaction conditions.Bornylene also undergoes a retro-Diels-Alder reaction to yield the trimethylcyclopentadiene and ethylene.
- Chuchani, Gabriel,Hernandez A, Jose A.,Morris, David G.,Shepherd, Alistair G.
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p. 917 - 922
(2007/10/02)
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- Kondakof Acylation of Logifolene/Camphene: A Comparative Study Using Boron Trifluoride Etherate/Stannic Chloride as Catalysts
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The Kondakof acylation of the ectocyclic methylene moiety in comphene (1) and its isoprene homologue longifolene (2) has been studied in acetic anhydride using BF3*OEt2/SnCl4 as catalysts.Ac2O-BF3*OEt2 fails to acylate (1) but gives isobornylacetate (3) (46percent) as the sole product.Acylation of (1) with Ac2O-SnCl4 affords ω-acetyl comphene (4) in a negligible yield (2percent) along with (3) in a much reduced yield (19percent).In sharp contrast, longifolene (2) generates ω-acetyllongifolene (5) with both the catalysts: BF3*OEt2 (24percent) and SnCl4 (16percent).The other compounds isolated in the former case are isolongifolene (6) (50percent) and transannular acetate (7) (2percent); in the latter case, (6) (17percent), (7) (5percent) and the novel tetracyclic methylketone (8) (11percent) are the co-products.The precurser for (8) has been shown to be the isomerized hydrocarbon (6), on direct acylation with SnCl4 generates (8).
- Dalavoy, V. S.,Deodhar, V. B.,Nayak, U. R.
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p. 907 - 910
(2007/10/02)
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