18409-17-1Relevant articles and documents
TOTAL SYNTHESIS OF CLAVULONES
Shibasaki, Masakatsu,Ogawa, Yuji
, p. 3841 - 3844 (1985)
Total synthesis of clavulones in naturally occurring form has been accomplished by the aldol coupling of the hydroxy-cyclopentenone 2 efficiently obtainable from 1,2-bis-trimethylsilyloxycyclopentene (4) by using 1,3-hydroxy transposition via the allylic methanesulfonate 11 and the α,β-unsaturated aldehyde 3.
Asymmetric Total Syntheses of Two Possible Diastereomers of Gliomasolide e and Its Structural Elucidation
Reddy, Ramidi Gopal,Venkateshwarlu, Ravula,Ramakrishna, Kallaganti V. S.,Yadav, Jhillu S.,Mohapatra, Debendra K.
, p. 1053 - 1063 (2017)
The first total syntheses of two possible diastereomers of gliomasolide E, a 14-membered macrolides isolated from the marine sponge Phakellia fusca Thiele, which was collected from the South China Sea, is reported. Highlights of the synthesis include macrolactonization through intramolecular Horner-Wadsworth-Emmons olefination, Yamaguchi-Hirao alkynylation, and base-induced elimination reactions for propargyl alcohol synthesis as the key reactions. Detailed comparison of their 1H and 13C NMR (1D and 2D NMR data) and specific rotation with those of the natural product revealed that the absolute stereochemistry of gliomasolide E should be (2E,5R,7R,9R,13R).
Biocatalytic asymmetric rearrangement of a methylene-interrupted bis-epoxide: Simultaneous control of four asymmetric centers through a biomimetic reaction cascade
Glueck, Silvia M.,Fabian, Walter M. F.,Faber, Kurt,Mayer, Sandra F.
, p. 3467 - 3478 (2004)
Asymmetric enzyme-catalyzed hydrolysis of methylene-interrupted bis-epoxides 1a and 1b catalyzed by bacterial epoxide hydrolases furnished tetrahydrofuran derivatives 2a and 2b through a hydrolysis-rearrangement cascade. Whereas racemic bis-oxiranes 1b-d underwent kinetic resolution with moderate stereoselectivities to yield products with up to 92% ee and 66% de: meso-bis-oxirane cis,cis-1a was transformed into (6R,7R,9S,10S)-2a in 94% ee and 89% de at high conversion (85%) by Rhodococcus sp. CBS 717.73 as the major product. The reaction sequence resembles a biomimetic reaction cascade and provides an efficient entry into the structural core of annonaceous acetogenins with simultaneous control of four stereocenters.
Production of 2-Octenyl Radicals from the Fe(III)*Bleomycin-Mediated Fragmentation of 10-Hydroperoxy-8,12-octadecadienoic Acid
Natrajan, Anand,Hecht, Sidney M.
, p. 5239 - 5241 (1991)
The Fe(III)*BLM-mediated fragmentation of 10-hydroperoxy-8,12-octadecadienoic acid was demonstrated unambiguously to occur via homolytic O-O bond scission.
CuBr2-catalyzed diastereoselective allylation: Total synthesis of decytospolides A and B and their C6-epimers
Choudhury, Utkal Mani,Mallampudi, N. Arjunreddy,Mohapatra, Debendra K.,Padhi, Birakishore,Reddy, G. Sudhakar
, p. 2685 - 2695 (2020/04/17)
An efficient CuBr2-catalyzed diastereoselective allylation of a cyclic hemiacetal with allyltrimethylsilane as a nucleophile has been developed. The protocol offers a cost effective, protecting group tolerant, and operationally simple approach to 2,6-trans-disubstituted tetrahydropyran with excellent diastereoselectivity. Furthermore, the application of this methodology has been demonstrated in the total synthesis of decytospolides A and B and their C6-epimers.
Synthesis of α,β-unsaturated aldehydes as potential substrates for bacterial luciferases
Brodl, Eveline,Ivkovic, Jakov,Tabib, Chaitanya R.,Breinbauer, Rolf,Macheroux, Peter
, p. 1487 - 1495 (2017/02/18)
Bacterial luciferase catalyzes the monooxygenation of long-chain aldehydes such as tetradecanal to the corresponding acid accompanied by light emission with a maximum at 490?nm. In this study even numbered aldehydes with eight, ten, twelve and fourteen carbon atoms were compared with analogs having a double bond at the α,β-position. These α,β-unsaturated aldehydes were synthesized in three steps and were examined as potential substrates in vitro. The luciferase of Photobacterium leiognathi was found to convert these analogs and showed a reduced but significant bioluminescence activity compared to tetradecanal. This study showed the trend that aldehydes, both saturated and unsaturated, with longer chain lengths had higher activity in terms of bioluminescence than shorter chain lengths. The maximal light intensity of (E)-tetradec-2-enal was approximately half with luciferase of P. leiognathi, compared to tetradecanal. Luciferases of Vibrio harveyi and Aliivibrio fisheri accepted these newly synthesized substrates but light emission dropped drastically compared to saturated aldehydes. The onset and the decay rate of bioluminescence were much slower, when using unsaturated substrates, indicating a kinetic effect. As a result the duration of the light emission is doubled. These results suggest that the substrate scope of bacterial luciferases is broader than previously reported.
Total Synthesis of Prostaglandin 15d-PGJ2 and Investigation of its Effect on the Secretion of IL-6 and IL-12
Egger, Julian,Fischer, Stefan,Bretscher, Peter,Freigang, Stefan,Kopf, Manfred,Carreira, Erick M.
supporting information, p. 4340 - 4343 (2015/09/15)
An efficient synthesis of 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2, 1) is reported. The route described allows for diversification of the parent structure to prepare seven analogues of 1 in which the positioning of electrophilic sites is varied. These analogues were tested in SAR studies for their ability to reduce the secretion of proinflammatory cytokines. It was shown that the endocyclic enone is crucial for the bioactivity investigated and that the conjugated ω-side chain serves in a reinforcing manner.
Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water
Talwar, Dinesh,Wu, Xiaofeng,Saidi, Ourida,Salguero, Noemí Poyatos,Xiao, Jianliang
supporting information, p. 12835 - 12842 (2015/03/30)
Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, β-keto esters and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. Water wonder: Iridicycle catalysts are versatile and allow the highly efficient and chemoselective transfer hydrogenation of a variety of carbonyl compounds, including problematic and challenging ones, with formate in neat water (see scheme).
Bis(imino)pyridine cobalt-catalyzed dehydrogenative silylation of alkenes: Scope, mechanism, and origins of selective allylsilane formation
Atienza, Crisita Carmen Hojilla,Diao, Tianning,Weller, Keith J.,Nye, Susan A.,Lewis, Kenrick M.,Delis, Johannes G. P.,Boyer, Julie L.,Roy, Aroop K.,Chirik, Paul J.
supporting information, p. 12108 - 12118 (2014/10/16)
The aryl-substituted bis(imino)pyridine cobalt methyl complex, ( MesPDI)CoCH3 (MesPDI = 2,6-(2,4,6-Me 3C6H2-N=CMe)2C5H 3N), promotes the catalytic dehydrogenative silylation of linear α-olefins to selectively form the corresponding allylsilanes with commercially relevant tertiary silanes such as (Me3SiO) 2MeSiH and (EtO)3SiH. Dehydrogenative silylation of internal olefins such as cis- and trans-4-octene also exclusively produces the allylsilane with the silicon located at the terminus of the hydrocarbon chain, resulting in a highly selective base-metal-catalyzed method for the remote functionalization of C-H bonds with retention of unsaturation. The cobalt-catalyzed reactions also enable inexpensive α-olefins to serve as functional equivalents of the more valuable α, ω-dienes and offer a unique method for the cross-linking of silicone fluids with well-defined carbon spacers. Stoichiometric experiments and deuterium labeling studies support activation of the cobalt alkyl precursor to form a putative cobalt silyl, which undergoes 2,1-insertion of the alkene followed by selective β-hydrogen elimination from the carbon distal from the large tertiary silyl group and accounts for the observed selectivity for allylsilane formation.
Homogeneous Pd-catalyzed transformation of terminal alkenes into primary allylic alcohols and derivatives
Tomita, Ren,Mantani, Kohei,Hamasaki, Akiyuki,Ishida, Tamao,Tokunaga, Makoto
supporting information, p. 9914 - 9917 (2014/08/18)
Synthesis of primary alcohols from terminal alkenes is an important process in both bulk and fine chemical syntheses. Herein, a homogeneous Pd-complex-catalyzed transformation of terminal alkenes into primary allylic alcohols, by using 5 mol % [Pd(PPh3)4] as a catalyst, and H2O, CO2, and quinone derivatives as reagents, is reported. When alcohols were used instead of H2O, allylic ethers were obtained. A proposed mechanism includes the addition of oxygen nucleophiles at the less-hindered terminal position of π-allyl Pd intermediates.
