- Sesquiterpene Cyclizations inside the Hexameric Resorcinarene Capsule: Total Synthesis of δ-Selinene and Mechanistic Studies
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The synthesis of terpene natural products remains a challenging task due to the enormous structural diversity in this class of compounds. Synthetic catalysts are unable to reproduce the tail-to-head terpene cyclization of cyclase enzymes, which create this diversity from just a few simple linear terpene substrates. Recently, supramolecular structures have emerged as promising enzyme mimetics. In the present study, the hexameric resorcinarene capsule was utilized as an artificial cyclase to catalyze the cyclization of sesquiterpenes. With the cyclization reaction as the key step, the first total synthesis of the sesquiterpene natural product δ-selinene was achieved. This represents the first total synthesis of a sesquiterpene natural product that is based on the cyclization of a linear terpene precursor inside a supramolecular catalyst. To elucidate the reaction mechanism, detailed kinetic studies and kinetic isotope measurements were performed. Surprisingly, the obtained kinetic data indicated that a rate-limiting encapsulation step is operational in the cyclization of sesquiterpenes.
- Zhang, Qi,Tiefenbacher, Konrad
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p. 12688 - 12695
(2019/08/12)
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- Total synthesis of α-cedrene: A new strategy utilizing N- aziridinylimine radical chemistry
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Tandem free radical cycloaddition reaction of the N-Aziridinylimine intermediate produced tricyclo[5.3.1.01,5]undecane skeleton stereoselectively. A total synthesis of α-cedrene was completed in three step sequence from the cyclization product.
- Lee, Hee-Yoon,Lee, Sejin,Kim, Deogil,Kim, Byung Kyu,Bahn, Jong Soo,Kim, Sunggak
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p. 7713 - 7716
(2007/10/03)
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- A Convenient and High Yielding Procedure for the Preparation of Isoselenocyanates. Synthesis and Reactivity of O-Alkylselenocarbamates.
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A high yielding one pot procedure for the preparation of isoselenocyanate from the corresponding formamide is reported.Various aromatic and aliphatic primary amines were employed in order to prepare the isoselenocyanates to establish the generality of the procedure.O-Alkylselenocarbamates of various primary, secondary and tertiary alcohols were synthesized and their stability and comparative reactivity were studied.Radical deoxygenation of the selenocarbamate of a secondary and a tertiary alcohol was accomplished under various conditions.
- Barton, Derek H. R.,Parekh, Shyamal I.,Tajbakhsh, Mahmoud,Theodorakis, Emmanouil A.,Tse, Chi-Lam
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p. 639 - 654
(2007/10/02)
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- THE DIRECT CONVERSION OF EPOXIDES INTO ALKENES via IODOHYDRINS BY in situ GENERATED HI
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Epoxides are easily converted into iodohydrins and alkenes are obtained from either epoxides or iodohydrins by treatment with HI, generated in situ from Ph3P*I2 in moist CH3CN.
- Garlaschelli, Luigi,Vidari, Giovanni
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p. 251 - 254
(2007/10/02)
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- Bicyclooctenones in Synthesis. A New Synthesis of (+/-)-Cedrene using Sequential Inter- and Intra-molecular Michael Reactions
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A new synthetic approach to cedrene (1) based on sequential inter- and intra-molecular Michael reactions using the bicyclooctenone (21) as the key intermediate is described.Michael addition of the enolate derived from (21) to 2-nitrobut-2-ene, led to a mixture of diastereoisomers of the nitro ketone (22), which was then converted into the 1,4-dione (23).Treatment of (23) with potassium t-butoxide in t-butyl alcohol resulted in smooth intramolecular Michael reaction leading to a mixture of α- (24a; major) and β-isomers of the tricyclo1,5>undecanedione (24) in a combined yield of 73percent.The undecanedione (24) was then converted into (+/-)-cedrene (1) and the corresponding methyl epimer (31a) via the intermediates (25), (26), (27), and (28).
- Horton, Michael,Pattenden, Gerald
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p. 811 - 817
(2007/10/02)
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- A NEW SYNTHESIS OF (+/-)-CEDRENE USING SEQUENTIAL INTER- AND INTRA-MOLECULAR MICHAEL REACTIONS
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A synthesis of (+/-)-cedrene (1), which features sequential intermolecular i.e.(2) -> (7), and intramolecular i.e. (8) -> (9), Michael reactions using the bicyclooctenone (2) as key intermediate, is described.
- Horton, Michael,Pattenden, Gerald
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p. 2125 - 2128
(2007/10/02)
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