- Diastereoselective Desymmetrization of p-Quinamines through Regioselective Ring Opening of Epoxides and Aziridines
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A highly diastereoselective desymmetrization of p-quinamines via regioselective ring opening of epoxides and aziridines under mild conditions has been developed. A chairlike six-membered transition state with minimized 1,3-diaxial interactions explains the relative stereoselectivity of the cyclization reaction. This transition-metal free [3 + 3] annulation reaction provides rapid access to fused bicyclic morpholines and piperazines with a tetrasubstituted carbon center in high yields. In addition, it also allows the synthesis of enantioenriched products by using easily accessible chiral nonracemic epoxides and aziridines.
- Jadhav, Sandip B.,Chegondi, Rambabu
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supporting information
p. 10115 - 10119
(2019/12/24)
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- Total synthesis, biological evaluation of dendrodolides A–D and their analogues
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A concise total synthesis of dendrodolides A–D (1–4) has been accomplished in 10 steps from commercially available (R)-propylene oxide and 3-buten-1-ol as starting materials. The key steps involved in the synthesis are Jacobsen hydrolytic kinetic resolution, epoxide ring opening with 2-allyl-1, 3-dithiane, Yamaguchi esterification and ring-closing metathesis (RCM). In addition, a series of ester derivatives were prepared utilizing Yamaguchi esterification at the C-3 position of the dendrodolide core and screened for their efficacy against cancer cell lines.
- Poornima,Venkanna,Swetha,Kamireddy, Karthik reddy,Siva, Bandi,Phani Babu,Ummanni, Ramesh,Babu, K. Suresh
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p. 4789 - 4797
(2016/07/18)
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- Regioselective and Stereospecific Copper-Catalyzed Deoxygenation of Epoxides to Alkenes
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Two copper salts (Cu(CF3CO2)2 and IMesCuCl) were identified as earth-abundant, inexpensive, but effective metal catalysts together with diazo malonate for chemo-/regioselective and stereospecific deoxygenation of various epoxides with tolerance of common functional groups (alkene, ketone, ester, p-methoxybenzyl, benzyl, tert-butyldimethylsilyl, and triisopropylsilyl). In particular, the unprecedented regioselectivity allowed for the first time monodeoxygenation of diepoxides to alkenyl epoxides. Density functional theory mechanistic studies showed that the deoxygenation occurred by collapsing the free ylide, unfavoring the possible intuitive pathway via cycloreversion of possible oxetane.
- Yu, Jingxun,Zhou, Yu,Lin, Zhenyang,Tong, Rongbiao
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supporting information
p. 4734 - 4737
(2016/09/28)
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- Total synthesis of (+)-monocerin via tandem dihydroxylation-SN2 cyclization and a copper mediated tandem cyanation-lactonization approach
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A simple and novel synthesis of (+)-monocerin was achieved in 15 steps and 15.5% overall yield from 3-buten-1-ol employing hydrolytic kinetic resolution, Julia olefination, intramolecular tandem Sharpless asymmetric dihydroxylation-SN2 cyclizat
- Nookaraju,Begari, Eeshwaraiah,Kumar, Pradeep
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p. 5973 - 5980
(2014/08/05)
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- The first stereoselective synthesis of dendrodolide A
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The first stereoselective total synthesis of natural product, dendrodolide A (1) is described from readily available (R)-propylene oxide and 3-buten-1-ol as starting materials. The synthesis was achieved in 10 steps with an overall yield of 19.1%. The key steps involved in the synthesis are Jacobsen hydrolytic kinetic resolution, epoxide ring opening with 2-allyl-1, 3-dithiane, Yamaguchi esterification, and ring-closing metathesis (RCM).
- Venkanna,Siva,Poornima,Babu, K. Suresh,Rao, J. Madhusudana
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p. 403 - 406
(2014/01/06)
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- Synthesis of cyclic alkenylsiloxanes by semihydrogenation: A stereospecific route to (Z)-alkenyl polyenes
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Cyclic alkenylsiloxanes were synthesized by semihydrogenation of alkynylsilanes - a reaction previously plagued by poor stereoselectivity. The silanes, which can be synthesized on multigram scale, undergo Hiyama-Denmark coupling to give (Z)-alkenyl polyene motifs found in bioactive natural products. The ring size of the silane is crucial: five-membered cyclic siloxanes also couple under fluoride-free conditions, whilst their six-membered homologues do not, enabling orthogonality within this structural motif.
- Elbert, Bryony L.,Lim, Diane S. W.,Gudmundsson, Haraldur G.,O'Hanlon, Jack A.,Anderson, Edward A.
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supporting information
p. 8594 - 8598
(2014/07/21)
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- Oxidative heck vinylation for the synthesis of complex dienes and polyenes
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We introduce an oxidative Heck reaction for selective complex diene and polyene formation. The reaction proceeds via oxidative Pd(II)/sulfoxide catalysis that retards palladium-hydride isomerizations which previously limited the Heck manifold's capacity f
- Delcamp, Jared H.,Gormisky, Paul E.,White, M. Christina
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supporting information
p. 8460 - 8463
(2013/07/19)
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- A total synthesis of spirastrellolide a methyl ester
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A concise total synthesis of spirastrellolide A methyl ester (1 a, R 1=Me) as the parent compound of a series of highly cytotoxic marine macrolides is disclosed, which exploits and expands the flexibility of a synthesis plan previously developed by our group en route to the sister compound spirastrellolide F methyl ester (6 a, R1=Me). Key to success was the masking of the signature Δ15,16-bond of 1 a as a C16-carbonyl group until after the stereogenic center at C24 had been properly set by a highly selective hydrogenation of the C24 exo-methylene precursor 66. Conformational control over the macrocyclic frame allowed the proper stereochemical course to be dialed into this reduction process. The elaboration of the C16 ketone to the C15-C16 double bond was accomplished by a chemoselective alkenyl triflate formation followed by a palladium-catalyzed hydride delivery. The role of the ketone at C16 as a strategic design element is also evident up-stream of the key intermediate 66, the assembly of which hinged upon the addition of the polyfunctionalized dithiane 37 to the similarly elaborate aldehyde fragment 46. Other crucial steps of the total synthesis were an alkyl-Suzuki coupling and a Yamaguchi lactonization that allowed the Northern and the Southern sector of the target to be stitched together and the macrocyclic perimeter to be forged. The lateral chain comprising the remote C46 stereocenter was finally attached to the core region by a modified Julia-Kocienski olefination. The preparation of the individual building blocks led to some methodological spin-offs, amongst which the improved procedure for the N-O-bond cleavage of isoxazolines by zero-valent molybdenum and the ozonolysis of a double bond in the presence of other oxidation-prone functionality are most noteworthy. Preliminary biological data suggest that the entire carbon framework, that is the macrocyclic core plus the lateral chain, might be necessary for high cytotoxicity. Copyright
- Arlt, Alexander,Benson, Stefan,Schulthoff, Saskia,Gabor, Barbara,Fürstner, Alois
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supporting information
p. 3596 - 3608
(2013/04/10)
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- Total synthesis and revision of the absolute configuration of seimatopolide B
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The asymmetric total synthesis of natural seimatopolide B along with its enantiomer is described starting from readily available 5-hexen-1-ol and 3-buten-1-ol. The key steps involved are Jacobson hydrolytic kinetic resolution, proline-catalyzed α-hydroxyl
- Reddy, Chada Raji,Dilipkumar, Uredi,Reddy, Motatipally Damoder,Rao, Nagavaram Narsimha
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p. 3355 - 3364
(2013/06/05)
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- Pheromone synthesis. Part 244: Synthesis of the racemate and enantiomers of (11Z,19Z)-CH503 (3-acetoxy-11,19-octacosadien-1-ol), a new sex pheromone of male Drosophila melanogaster to show its (S)-isomer and racemate as bioactive
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The enantiomers of (11Z,19Z)-3-acetoxy-11,19-octacosadien-1-ol were synthesized from the enantiomers of 3,4-epoxy-1-butanol PMB ether. Its racemate was also synthesized. Its (S)-isomer and racemate were shown to possess the same pheromone activity as CH503, a long-lived inhibitor of male courtship in Drosophila melanogaster, although the racemate was less active.
- Mori, Kenji,Shikichi, Yasumasa,Shankar, Shruti,Yew, Joanne Y.
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experimental part
p. 7161 - 7168
(2010/10/01)
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- Synthesis of (-)-galantinic acid via iterative hydrolytic kinetic resolution and tethered aminohydroxylation
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A new synthetic strategy for (-)-galantinic acid is reported using iterative hydrolytic kinetic resolution and tethered aminohydroxylation as the key steps.
- Dubey, Abhishek,Kauloorkar, Shruti V.,Kumar, Pradeep
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experimental part
p. 3159 - 3164
(2010/06/11)
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- An efficient total synthesis of decarestrictine D
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An efficient total synthesis of decarestrictine D has been achieved using cross-metathesis or ring-closing metathesis and Yamaguchi macrolactonization as key steps. The stereogenic centres were generated by means of hydrolytic kinetic resolution (HKR) and
- Gupta, Priti,Kumar, Pradeep
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experimental part
p. 1195 - 1202
(2009/04/07)
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- Synthesis of the C6-C21 segment of amphidinolide E
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(Chemical Equation Presented) A convergent approach to a C6-C21 segment of the polyketide amphidinolide E has been developed through combination of three subunits by allenylindium bromide-aldehyde addition and Suzuki sp 2-sp3 couplin
- Marshall, James A.,Schaaf, Gregory,Nolting, Andrew
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p. 5331 - 5333
(2007/10/03)
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- Stereocontrolled total synthesis of (+)-leucascandrolide A
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Apparently no longer available from its natural source is the potent cytotoxic and antifungal agent leucascandrolide A (1), which was initially isolated from a New Caledonian calcareous sponge. A highly stereocontrolled total synthesis of this structurally unique macrolide commences with a Jacobsen asymmetric hetero Diels-Alder reaction to configure the tetrahydropyran ring. An efficient endgame relies on two Mitsunobu reactions, the first to generate the 18-membered macrolactone and the second to attach the oxazole-bearing side chain.
- Paterson, Ian,Tudge, Matthew
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p. 343 - 347
(2007/10/03)
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- Structure Assignment, Total Synthesis, and Antiviral Evaluation of Cycloviracin B1
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The first total synthesis of the antivirally active glycolipid cycloviracin B1 (1) is described. The approach is based on a two-directional synthesis strategy which constructs the C 2-symmetrical macrodiolide core of the target by an
- Fuerstner, Alois,Albert, Martin,Mlynarski, Jacek,Matheu, Maribel,DeClercq, Erik
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p. 13132 - 13142
(2007/10/03)
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