- Pore-engineered silica-alumina: Texture, acidity, and activity for conversion of longifolene to isolongifolene
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Pore-engineered silica-alumina was synthesized for the conversion of longifolene to isolongifolene, and the effects of texture and surface properties on the activity were examined. The acidity and texture of the modified silica-alumina play a vital role in governing the catalytic isomerization of longifolene to isolongifolene. A conversion of 97% of longifolene with 95% selectivity has been achieved. Springer-Verlag 2011.
- Patial, Jyoti,Dar, Bashir Ahmad,Sharma, Parveen,Kumar, Kusunuru Anil,Sharma,Ray, Shyam Kr,Mukharjee, Debaraj,Singh, Baldev
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- Synthesis in fluorous phase: A convenient synthesis of isolongifolene epoxide and its rearrangement to ketone
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Aerobic epoxidation of isolongifolene 1 with pivalaldehyde/oxygen in perfluoro-2-butyltetrahydrofuran (FC-75) in the presence of Mn(OAc)3·2H2O as catalyst yielded isolongifolene-epoxide 3 in good yield. The rearrangement of isolongifolene-β-epoxide to ketone 4 was achieved.
- Ravikumar,Bégué, Jean-Pierre,Bonnet-Delpon, Danièle,Ourévitch, Michèle
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- STUDIES IN SESQUITERPENES--LVI ISOLONGIFOLENE (Part 7): MECHANISM OF REARRANGEMENT OF LONGIFOLENE TO ISOLONGIFOLENE--II
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The question of possible neutral intermediates which may lie on the reaction pathway in going from longifolene to isolongifolene has been investigated using BF3*Et2O-AcOD and D3PO4-dioxane, as reagents.It has been found that longicyclene is not an obligat
- Yadav, J. S.,Soman, R.,Sobti, R. R.,Nayak, U. R.,Dev, Sukh
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- ALLOISOLONGIFOLENE, A UNIQUE ACID-CATALYZED ISOMER OF LONGIFOLENE
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A remarkably catalyst-specific rearrangement of longifolene 1 to a new tricyclic isomer, alloisolongifolene 3, has been discovered after more than two decades of dormancy since the first acid-catalysed isomer, isolongifolene 2, was unravelled by us.
- Shitole, H. R.,Vyas, Pramod,Nayak, U. R.
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- Method for preparing different long Ye Xi
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The invention discloses a preparation method of isolongifolene. The preparation method comprises the following steps: sequentially adding longifolene and a catalyst into a reaction kettle, uniformly stirring, introducing supersonic waves into the reaction kettle, gradually heating to 90-100DEG C, and carrying out an isomerization reaction for 45-60min to obtain isolongifolene, wherein the catalyst is one or two or more of zinc oxide, cobalt acetate and sodium hyposulfite. The method has the advantages of shortening of the reaction time, increase of the raw material conversion rate, and high purity of the above obtained product.
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Paragraph 0012-0014; 0016-0017; 0019-0020
(2018/02/04)
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- Studies in sesquiterpenes-lx reversion of longipinane to himachalane system: Revision of structure of isocentdarol
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Longipinene on exposure to acids rapidly rearranges to furnish α- and β-himachalenes, longifolene and isolongifolene. Longipinene epoxide, under acid catalysis, gives several products resulting from fragmentation and Wagner-Meerwein rearrangement. All products have been fully characterised. Formation of isocentdarol in this reaction requires revision of its stereochemistry at the centre carrying tertiary hydroxyl function.
- Shastri, Mayank H.,Dev, Sukh
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p. 4905 - 4918
(2007/10/02)
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- Base-induced Thermal Decomposition of Terpenoid Tosylhydrazones: Part II - Chemistry of 8-diazoisolongifolane/9-Diazoisolongifolene
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7αH-8-Oxoisolongifolane (3) on refluxing with tosylhydrazine in CHCl3 gives the tosylhydrazone (7) of the more stable epimer 7βH-8-oxoisolongifolane (6).Refluxing 7 with NaOMe in diglyme gives the disubstituted olefin (15, 31percent), isolongifolene (2, 23percent) and the unusual alcohol (16, 7percent).Two pure C-8 epimers of the 2-hydroxyethyl ether 17 (27percent)/18 (6percent) are formed in the protic Bamford-Stevens reaction (Na in ethylene glycol) on 7; isolongifolene (2, 20percent) and 15 (13percent) are the other products.Attempted preparation of the tosylhydrazone (10) from 8-oxoisolongifol-9-ene (9) generates only the saturated tosylhydrazone (7) via a concomitant reduction of the the olefinic bond in 9 during the reaction. 9-Diazoisolongifolene (14) generated from the tosylhydrazone (13) under aprotic conditions gives the vinylcarbene-derived olefinic methyl ether epimers (20/21) in a major yield (47percent) while the the diene (19, 6percent) and the crystalline azine (22, 4percent) are also formed.Refluxing 13 with Na in ethylene glycol generates the C-9 ethylene glycol substituted compound (23) (54percent) with only a trace (4percent) of 19.
- Satyanarayana, N.,Nayak, U. R.
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- Silver Ion-Assisted Solvolysis of 8,11-Dibromolongibornane: Generation of Novel Skeletally Rearranged Olefinic Carbinols
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The disecondary bromide, 8,11-dibromolongibornane (3) on exposure to silver perchlorate in aqueous acetone gives predominantly a mixture of three olefinic carbinols, of which a unique ring-expanded alcohol (7) constitutes 65percent; the assigned structure has been confirmed by an X-ray anaylsis of its p-bromobenzoate.Of the other two minor alcohols (separable only in the form of their ketones), one has been characterized as 10-ketolongifolene (15); the other keto-olefin which is highly hindered and resistant to Wolff-Kishner reduction has been assigned one of two possible structures 12/13 based on spectral data.The minor hydrocarbon fraction (6percent) has been shown to consist of two compounds of which only one has beencharacterized as dehydrolongifolene (22).
- Reddy, R. Thimma,Nayak, U. R.
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p. 585 - 588
(2007/10/02)
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- Base-induced Thermal Decomposition of Terpenoid Tosylhydrazones: Part I - Chemistry of Diazolongibornanes
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The elusive progenitor neolongifolene (6) of Isolongifolene (2) has been synthesized (44percent yield) from longicamphor tosylhydrazone (8) by generating the crucial longibornyl-10-cation (5) under basic conditions in a protic (sodium-ethylene glycol) Bamford-Stevens reaction; Longicyclene (13, 15percent) and the ether-carbinol(14, 16percent) are the other products.Exposure of 6 to BF3.OEt2 in benzene transforms it to 2.Under aprotic conditions (sodium methoxide-diglyme) 8 gives longicyclene (13) as the major product (41percent) with a trace (5percent) of 6.When 8 is exposed to n-butyllithium in hexane, the novel longibornylene (21) (54percent) is formed.Generation of anelectron-deficient species at the C-4 position on the longibornane skeleton via 24->25->26 has been studied: a novel transannular carbene insertion product 30 is formed from 24 under aprotic conditions only .In this reaction olefins 27 and 28 are very minor (5percent); the major crystalline compound is the 4-oxolongibornane azine (31) (ca. 30percent).Refluxing 24 in ethylene glycol with the sodium salt of ethylene glycol yields 27 (15percent) and 28 (16percent), besides the oxygenated compound 29 (19percent).
- Satyanarayana, N.,Nayak, U. R.
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- Alloisolongifolene: A Unique Acid-catalysed Isomer of Longifolene
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A catalyst-specific rearrangement of longifolene (1) to a new tricyclic isomer, alloisolongifolene (10) is described.The structure (10) for alloisolongifolene has been derived by an X-ray crystal structure analysis of the p-nitrobenzoate (9) prepared from the primary alcohol (8) resulting from the hydroboration of the 10.Hydrolysis of the ester resulting from the Baeyer-Villiger oxidation of the methyl ketone (14) derived from the periodate-permanganate oxidation of 10 gives the trisnor C12-tertiary alcohol (16).Chromic acid oxidation of 10 generates the same carbon--cleaved ketone (14) and alloisolongifolic acid (15) derived from a terminal oxidation of the olefin.
- Shitole, H. R.,Vyas, P.,Nayak, U. R.
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p. 702 - 706
(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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- STUDIES IN SESQUITERPENES-LV ISOLONGIFOLENE(PART 6): MECHANISM OF REARRANGEMENT OF LONGIFOLENE TO ISOLONGIFOLENE-I
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The gross mechanism of rearrangement of longifolene to isolongifolene has been elucidated by using site-specifically labelled longifolene-4,4,5,5-d4 and shown to follow the pathway proposed by Berson et al., which involves an exo, exo Me shift, in preference to the endo, endo Me migration route proposed earlier.An efficient synthesis of longifolene-4,4,5,5-d4, the key compound in the present investigation, is described.
- Yadav, J. S.,Nayak, U. R.,Dev, Sukh
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p. 309 - 315
(2007/10/02)
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