- A general synthetic approach to para-cyclophanes via ring-closing metathesis
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A new methodology for the synthesis para-cyclophanes and longithorone C frameworks has been demonstrated via alkylation, ceric ammonium nitrate (CAN) oxidation and ring-closing metathesis as key steps.
- Kotha, Sambasivarao,Shirbhate, Mukesh E.
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p. 1483 - 1494
(2016/02/26)
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- A general synthetic approach to para-cyclophanes via ring-closing metathesis
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A new methodology for the synthesis para-cyclophanes, and longithorone C frameworks has been demonstrated via alkylation, eerie ammonium nitrate (CAN) oxidation and ring-closing metathesis as key steps.
- Kotha, Sambasivarao,Shirbhate, Mukesh E.
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p. 1483 - 1494
(2016/09/09)
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- A mild Lewis acid mediated epoxy-ester to bicyclic ortho ester rearrangement
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A high yielding rearrangement of epoxy-esters, under Lewis acid conditions, to give bicyclic ortho esters is reported.
- Ahmed, Awais,Christie, Steven D. R.,Elsegood, Mark R. J.,Pritchard, Gareth J.
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p. 7489 - 7491
(2013/08/23)
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- Diversity-oriented approach to macrocyclic cyclophane derivatives via ring-closing metathesis
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A short synthetic approach to the macrocyclic framework of longithorone C is described via ring-closing metathesis using the Grubbs 2nd generation catalyst. Georg Thieme Verlag Stuttgart ? New York.
- Kotha, Sambasivarao,Shirbhate, Mukesh E.
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p. 2183 - 2188
(2012/11/07)
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- New Ugi-Smiles-metathesis strategy toward the synthesis of pyrimido azepines
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(Chemical Equation Presented) A new strategy involving Ugi-Smiles coupling followed by ring-closure metathesis is described herein for the preparation of pyrimidine-fused heterocyclic scaffolds. The scope of this sequence is presented in relation with the
- El Kaim, Laurent,Grimaud, Laurence,Oble, Julie
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p. 5835 - 5838
(2008/02/09)
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- Stereospecific syntheses of sex pheromones of the californian red scale and white peach scale (Homoptera: Diaspididae) based on 1,4-cis-hydrogenation of dienes
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Stereospecific syntheses of (+/-)-3-methyl-6-isopropenyl-3(Z),9-decadien-1-yl acetate and (+/-)-3,9-dimethyl-6-isopropenyl-3(Z),9-decadien-1-yl propionate (the Racemoc forms of the pheromones of the scales Aonidiella aurantii and Pseudaulascaspis pentagona) with a geometrical purity of the (Z)-trisubstituted double bond not lower than 99percent were performed.The key step in both syntheses was the 1,4-cis-hydrogenation of the corresponding ethyl 3-methyl-6-(1,1-ethylenedioxyethyl)-2,4,9-decatrienoates catalyzed with chromium carbonyl complexes.These 2,4-dienes were obtained in five conventional steps including the alkylation of ethyl acetoacetate by the appropriate 1-bromo-3-butenes and the Horner-Emmons olefination of the corresponding α-branched aldehydes. - Keywords: (+/-)-3-methyl-6-isopropenyl-3(Z),9-decadien-1-yl acetate, (+/-)-3,9-dimethyl-6-isopropenyl-3(Z),9-decadien-1-yl propionate, synthesis, aldehydoketals, ethyl 2,4-alkadienoates, 1,4-cis-hydrogenation, the Horner-Emmons olefination, ethyl acetoacetate, alkylation, arene chromium tricarbonyl complexes
- Vasil'ev, A. A.,Vlasyuk, A. L.,Kryshtal, G. V.,Serebryakov, E. P.
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p. 1946 - 1951
(2007/10/03)
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- Synthesis of spirocyclic acetals by manganic acetate promoted additions to exocyclic enol ethers
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Reaction of β-ketoesters and β-dicarbonyl compounds with manganic acetate in acetic acid gives intermediates, which add to exocyclic enol ethers to afford a variety of interesting spirocyclic acetals. As the exocyclic enol ethers are shown to be readily a
- Mellor, John M.,Mohammed, Shahid
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p. 7567 - 7578
(2007/10/02)
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- Photochemistry of Cyclic Enones. Part 8. 5-(But-3-enyl)-3-phenylcyclopent-2-enone and 5-(Pent-4-enyl)-3-phenylcyclopent-2-enone
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Photolysis of 5-(but-3-enyl)-3-phenylcyclopent-2-enone in benzene solution using Pyrex filter affords two products in the ratio 2:1.These are 1-phenyltricyclo3,8>nonan-7-one and 8-phenyltricyclo3,8>nonan-9-one.They are inseparable by column chromatogryphy, but their structure follows from examination of the four separable lactones derived from the mixture by Baeyer-Villiger oxidation.Photolysis of 5-(pent-4-enyl)-3-phenylcyclopent-2-enone under the same conditions affords only one product, 9-phenyltricyclo3.9>decan-10-one, whose structure follows from examination of the two lactones derived by similar oxidation.These results demonstrate that in these compounds the regioselectivity of ring depends on the length of the 5-side-chain.
- McMurry, T. Brian H.,Work, Annemarie,McKenna, Brian
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p. 811 - 816
(2007/10/02)
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- Synthesis and X-ray crystal structure determination of 1,3-bridged β-lactams: Novel, anti-Bredt β-lactams
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The first successful syntheses of several anti-Bredt β-lactams from alkyl acetoacetate in 11-14 steps are described. The key cyclization reaction involves the Rh(II)-catalyzed carbene insertion of the diazo derivatives 12, 23, and 31 into the N-H bond of the β-lactams. These (±)-1,3-bridged β-lactams have IR absorptions of 1780-1795 cm-1 for the β-lactam carbonyls. The structure of 32d has been determined by X-ray crystallography; this derivative exhibits a C-N (amide) bond length of 1.414 (4) A and a β-lactam pyramid with the nitrogen atom 0.51 A above the basal plane of three carbon atoms.
- Williams,Lee,Miller,Anderson
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p. 1073 - 1081
(2007/10/02)
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- CONVENIENT SYNTHETIC ROUTE TO (+/-) -FRONTALIN
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(+/-)-Frontalin was synthesized in a few steps sequence starting from ethyl acetoacetate involving intramolecular cyclization using palladium chloride as catalyst
- Kongkathip, Boonsong,Sokkho, Rongsan,Kongkathip, Ngampong
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p. 1849 - 1850
(2007/10/02)
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- FREE RADICAL REARRANGEMENTS OF ORGANOCOBALOXIMES: ALKYNYL TO CYCLOALKYLIDENE AND HEXENYL TO CYCLOPENTYLMETHYL
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Under irradiation by tungsten light in pyridine solution, several substituted alkylcobaloximes undergo rearrangement to more stable substituted alkyl- or alkenyl-cobaloximes.When the same reactions are carried out in the presence of carbon tetrachloride or chloroform, no rearranged organobaloximes are obtained, but a variety of organic products are obtained derived from the interception of transient organic radicals by the halogenated solvent.The rearrangements are rationalised in terms of a reversible homolysis of the carbon-cobalt bond, rearrangement of the organic radical and recapture by the cobalt(II) fragment to give complexes that are more stable to irradiation than their precursors.
- Bougeard, Peter,Cooksey, Christopher J.,Johnson, Michael D.,Lewin, Melanie J.,Mitchell, Stewart,Owens, Paul A.
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p. 349 - 358
(2007/10/02)
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