- (+)-camphorsulfonylimine
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The norbornane ring system in the title molecule, 8, 8-dimethy 1-3, 3a, 4,5,6,7-hexahydro-3a, 6-methanobenz[c]isothiazole S,S-dioxide, C10H15NO2S, is regular with normal bond lengths and angles. The bridgehead bond angle is 92.5 (2)°. The five-membered ring of the sulfonylimine moiety adopts a flattened envelope conformation. The crystal structure is stabilized by weak C - H. . .O hydrogen bonds.
- Chakraborty, Arindam,Ray, Jayanta Kumar,Chinnakali, Kandasamy,Razak, Ibrahim Abdul,Fun, Hoong-Kun
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- Palladium-Catalyzed Stereoselective Cyclization of in Situ Formed Allenyl Hemiacetals: Synthesis of Rosuvastatin and Pitavastatin
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A diastereoselective palladium-catalyzed cyclization of allenyl hemiacetals is described. It permits the selective synthesis of 1,3-dioxane derivatives, precursors for syn-configured 1,3-diols which make an appearance in all of the statin representatives. The reaction allows the total synthesis of Rosuvastatin and Pitavastatin in a straightforward fashion.
- Spreider, Pierre A.,Breit, Bernhard
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supporting information
p. 3286 - 3290
(2018/06/11)
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- Improved synthesis of N-sulfonylformamidine derivatives promoted by thionyl chloride
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An improved synthesis of N-sulfonylformamidine derivatives has been developed involving direct condensation of various sulfonamides and formamides in the presence of thionyl chloride using chloroform as solvent. Detailed synthetic studies indicate that th
- Hudabaierdi, Ruzeahong,Wusiman, Abudureheman,Mulati, Ayinigeer
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p. 485 - 489
(2017/05/01)
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- Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds
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Compounds containing two alkyne groups in close vicinity at the rigid skeleton of camphorsulfonamide show unique reactivities when treated with electrophiles or catalytic amounts of platinum(II). The formed product structures depend not only on the reagents used but also on the substituents attached to the triple bonds. Cycloisomerisations with perfect atom economy lead to polycyclic heterocycles that resemble to some extent the AB ring system of paclitaxel. Herein, we present practical synthetic methods for the selective synthesis of precursor dialkynes bearing different substituents (alkyl, aryl) at the triple bonds, based on ketals or an imine as protecting groups. We show for isomeric dialkynes that the reaction cascade induced by Pt(II) includes ring annulation, sulphur reduction, and ring enlargement. One isomeric dialkyne additionally allows for the isolation of a pentacyclic compound lacking the ring enlargement step, which we have proposed as a potential intermediate in the catalytic cycle.
- Carvalho, M. Fernanda N. N.,Herrmann, Rudolf,Wagner, Gabriele
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p. 1230 - 1238
(2017/07/03)
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- Influence of norbornanone substituents on both the Wagner-Meerwein skeletal rearrangements under sulfonation conditions and the diastereoselectivity of the corresponding N,N′-bis-fumaroyl sultams in uncatalyzed Diels-Alder cycloadditions to cyclopenta-1,3-diene
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The Wagner-Meerwein domino rearrangement of norbornanone skeletons, under sulfonation conditions, is strongly influenced by the absence of a gem-dimethyl moiety at C(7). As a result, sulfonation at C(10) is less efficient due to a divergent pathway in the intermediate double bond formation and/or isomerization. Furthermore, the absence of such a gem-dimethyl moiety in the corresponding norbornane[10,2]sultam derivatives, sterically influences the orientation of the SO(1) and SO(2) substituents, hence on the π-facial steric shielding of the thermodynamically more stable anti-s-cis N-alkenoyl dienophiles. As a consequence, their diastereoselective [4+2] cycloadditions to cyclopenta-1,3-diene, under nonchelating conditions, are not as efficient due to a less pseudo axial SO(1) and the consequent loss of pseudo C 2-symmetry.
- Pia?tek, Anna,Chapuis, Christian
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p. 4247 - 4249
(2013/07/26)
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- Process for Production of Optically Active Carboxlic Acid Compound
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An optically active acylated camphorsultam can be hydrolyzed with an aqueous solution of an alkaline earth metal hydroxide in the presence of a branched alkanol, to give a corresponding optically active carboxylic acid compound in safely and inexpensively
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Page/Page column 6
(2009/05/28)
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- Total syntheses of epothilones B and D
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A convergent, total synthesis of epothilones B (2) and D (4) is described. The key steps are Normant coupling to establish the desired (Z)-stereochemistry at C12-C13, Wadsworth-Emmons olefination of methyl ketone 28 with the phosphonate ester 8, diastereoselective aldol condensation of aldehyde 5 with the enolate of keto acid derivatives to form the C6-C7 bond, selective deprotection of acid 52, and macrolactonization.
- Jung, Jae-Chul,Kache, Rajashaker,Vines, Kimberly K.,Zheng, Yan-Song,Bijoy, Panicker,Valluri, Muralikrishna,Avery, Mitchell A.
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p. 9269 - 9284
(2007/10/03)
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- A practical synthesis of optically active (R)-2-propyloctanoic acid: Therapeutic agent for Alzheimer's disease
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(R)-2-Propyloctanoic acid has been developed as a novel therapeutic agent for Alzheimer's disease. A large-scale synthesis of this candidate was achieved by using Oppolzer's camphorsultam as a chiral auxiliary under improved conditions. It was essential for the successful synthesis of this compound to utilize a new removal method for the chiral source with a combination of tetrabutylammonium hydroxide and hydrogen peroxide. The present process afforded the desired product in high yield with high optical purity.
- Hasegawa, Tomoyuki,Yamamoto, Hisashi
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p. 423 - 428
(2007/10/03)
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- Progress toward the total synthesis of callipeltin A (I): Asymmetric synthesis of (3S,4R)-3,4-dimethylglutamine
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(equation presented) During the total synthesis of the novel cyclic depsipeptide callipeltin A (1), the unit (3S,4R)-3,4-dimethylglutamine, was successfully synthesized by asymmetric Michael addition and subsequent electrophilic azidation. The key feature of this approach is the generation of three adjacent stereogenic centers using the same camphorsultam chiral auxiliary.
- Liang, Bo,Carroll, Patrick J.,Joullie, Madeleine M.
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p. 4157 - 4160
(2007/10/03)
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- Novel application of chiral micellar media to the Diels-Alder reaction
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A novel chiral surfactant has been used in the first reported aqueous chiral micellar catalysis of a Diels-Alder reaction and enantioselectivities have been observed.
- Diego-Castro, Michael J.,Hailes, Helen C.
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p. 1549 - 1550
(2007/10/03)
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- A two-step synthesis of camphosultam
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Modifications of the known route to camphosultam led to an easy two-step process. The unique intermediate is simply isolated by filtration. The overall yield is 66% on a hundred gram scale.
- Capet,David,Bertin,Hardy
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p. 3323 - 3327
(2007/10/03)
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- Methylenecyclopropanes, XI. - Asymmetric Nickel(0)-Catalyzed Cycloadditions of Methylenecyclopropanes with Chiral Derivatives of Acrylic Acid
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The nickel(0)-catalyzed codimerisation of methylenecyclopropane 1a or 2,2-dimethylmethylenecyclopropane (1b) with the chiral derivatives of acrylic acid 2a-2f leads to the optically active 3-methylenecyclopentanecarboxylic esters 3a, 3c-3f, 4a, and 4c, or amides 3b and 4b in good yields.The diastereomeric excess accesible depends on the steric demand of the chiral auxiliaries, de values up to 98percent can be achieved.Some improvements of the preparation of optically pure auxiliaries are also described.
- Binger, Paul,Brinkmann, Axel,Roefke, Petra,Schaefer, Bernd
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p. 739 - 750
(2007/10/02)
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- Camphor-Derived N-Acryloyl and N-Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels-Alder Reactions
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Starting from (+)-camphor-10-sulfonyl chloride (5), the crystalline sultam 8 was easily prepared.Lewis-acid-promoted Diels-Alder additions of the crystalline N-acryloyl and N-crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3-butadiene at -130 to -78 grad furnished adducts 11, 12 and 17 with high chiral efficiency.Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 or acid 19 in 99percent enantiomeric purity.The sense of induction was reversed on using the enantiomer of 8 as the auxiliary.The structure of 10 was established by X-ray diffraction analysis
- Oppolzer, Wolfgang,Chapuis, Christian,Bernardinelli, Gerald
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p. 1397 - 1401
(2007/10/02)
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