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21.
K. Rajalakshmi Vasantha Pattabhi C. S. Venkatesan G. Nadamuni A. Srikrishna 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):e307-e308
In the title compound, C29H42O4·H2O, cyclohexane rings A and B are in the sofa conformation, ring C is in a chair conformation and the five‐membered ring D is in an envelope conformation. The structure is stabilized by inter‐ and intramolecular C—H?O and O—H?O hydrogen bonds. 相似文献
22.
Enantiospecific first total synthesis of the angular triquinane sesquiterpene (6S,7R)-silphiperfolan-6-ol has been accomplished, starting from 2-(3-isopropenyl-2-methylene-1-methylcyclopent-1-yl)acetic acid (readily available from (R)-limonene) employing an efficient, regioselective intramolecular rhodium carbenoid insertion into the CH bond of a tertiary methyl group as the key step. 相似文献
23.
Srikrishna Tummala Wei-An Huang Bo-Hong Wu Prof. Kai-Chih Chang Prof. Yen-Peng Ho 《ChemistryOpen》2020,9(10):1074-1081
We present a sensitive and rapid screening method for the determination of β-lactamase activity of antibiotic-resistant bacteria, by designing a pH-sensitive fluorescent dye-doped mesoporous silica nanoparticle encapsulated with penicillin G as a substrate. When penicillin G was hydrolysed by β-lactamase and converted into penicilloic acid, the acidic environment resulted in fluorescence quenching of the dye. The dye-doped mesoporous nanoparticles not only enhanced the β-lactamase-catalyzed reaction rate but also stablized the substrate, penicillin G, which degrades into penicilloic acid in a water solution without β-lactamase. Twentyfive clinical bacterial samples were tested and the antibiotic resistant and susceptible strains were identified. The proposed method may detect the presence of β -lactamases of clinically relevant samples in less than 1 hour. Moreover, the detection limit of β-lactamase activity was as low as 7.8×10−4 U/mL, which was determined within two hours. 相似文献
24.
An enantiospecific synthesis of the [6.6.3]-tricyclic carbon framework, 2,6,6,9-tetra-methyltricyclo[5.4.0.02,4]undecane, present in the sesquiterpenes lippifolianes and the diterpenes cyclosclareol, metasequoic acids and parguerols, starting from the readily available monoterpene (R)-carvone, is described. 相似文献
25.
The enantioselective syntheses of diquinane and cis, anti, cis-linear triquinanes, starting from the readily available (S)-campholenaldehyde, employing an intramolecular rhodium carbenoid CH insertion reaction, are described. 相似文献
26.
Photochemistry of tricyclo [4.2.2.02,5] deca-3,7-dien-9-one: a source of many interesting polycycles
New syntheses of tricyclo [4.2.2.02,5] deca-3,7-dien-9-one are described. Direct and sensitised photolysis of this ring system provides facile entry to several novel polycyclics. 相似文献
27.
Enantiospecific synthesis of the natural enantiomer of the marine sesquiterpene (-)-4-thiocyanatoneopupukeanane (6) is described. The bicyclo[2.2.2]octanecarboxylate 14, obtained from (R)-carvone via Michael-Michael reaction, was transformed into neopupukeananedione 12 by employing rhodium acetate catalyzed intramolecular C-H insertion of the diazo ketones 16 or 19 as the key reaction. Regioselective deoxygenation of the C-2 ketone transformed the dione 12 into neopupukean-4-one 10. Alternately, the keto ester 18 was also transformed into neopupukean-4-one 10 via regioselective deoxygenation of the ketone in 18 followed by intramolecular rhodium carbenoid C-H insertion of the diazo ketone 31. Finally, neopupukean-4-one 10 was transformed into (-)-4-thiocyanatoneopupukeanane 6 via the alcohol 32 and the mesylate 33. 相似文献
28.
A novel olefin metathesis sequence permits ready access to functionalised , , -tricyclo [6.3.0.02,6] undecane based bis-enones. These bis-enones have been shown to undergo cage cyclisation in sunlight with remarkable ease and efficiency. 相似文献
29.
30.
Srikrishna Bera Dr. Constantin G. Daniliuc Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2017,56(26):7402-7406
An efficient method for the asymmetric intramolecular dearomatization of indoles by using oxidative N-heterocyclic carbene catalysis is demonstrated. Valuable optically active spirocyclic indolenines bearing an all-carbon quaternary stereocenter are obtained in excellent yields and with excellent enantioselectivity. The starting indoles are readily prepared and the reactions proceed through an intramolecular indole 3-acylation with an in situ generated acyl azolium intermediate to form a spirocyclic ketone moiety. 相似文献