- Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
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The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
- Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
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p. 302 - 305
(2022/01/03)
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- Synthesis of C -glycoside analogues of α-galactosylceramide via linear allylic C-H oxidation and allyl cyanate to isocyanate rearrangement
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C-Glycoside analogues of α-galactosylceramide were synthesized in which several significant modifications known to promote Th-1 cytokine production were included. The key transformations include C-H oxidation, Sharpless asymmetric epoxidation, olefin cros
- Liu, Zheng,Bittman, Robert
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supporting information; scheme or table
p. 620 - 623
(2012/03/22)
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- Ring-opening hydrofluorination of 2,3- and 3,4-epoxy amines by HBF 4·OEt2: Application to the asymmetric synthesis of (S, S)-3-deoxy-3-fluorosafingol
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Treatment of a range of 2,3- and 3,4-epoxy amines with HBF 4·OEt2 at room temperature results in fast and efficient SN2-type ring-opening hydrofluorination to give stereodefined amino fluorohydrins. Operational simplicity, scalability, and short reaction time at ambient temperature are notable features of this method. The utility of this methodology is exemplified in a concise asymmetric synthesis of (S,S)-3-deoxy-3-fluorosafingol.
- Cresswell, Alexander J.,Davies, Stephen G.,Lee, James A.,Morris, Melloney J.,Roberts, Paul M.,Thomson, James E.
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experimental part
p. 4617 - 4627
(2011/07/30)
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- An improved two-step synthetic route to primary allylic alcohols from aldehydes
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An improved two-step synthetic route to allylic alcohols from aldehydes has been developed. A modification of the HWE reaction in H2O-2-PrOH (1 : 1) and a convenient protocol to prepare AlH3 in THF from LiAlH 4 and n-BuBr are the key factors in the improvement.
- Liu, Zheng,Gong, Yaqiong,Byun, Hoe-Sup,Bittman, Robert
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experimental part
p. 470 - 475
(2010/06/14)
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- Asymmetric total syntheses of spisulosine, its diastereo- and regio-isomers
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Starting from palmityl alcohol, divergent stereoselective syntheses of spisulosine and its diastereo- and regio-isomers have been achieved. In the Sharpless asymmetric dihydroxylation-based approach, the key step is the synthesis of monoprotected diol, whereas Miyashita's boron-directed C-2 regioselective azidolysis of enantiomerically pure epoxy alcohol is the vital step in the Sharpless asymmetric epoxidation-based route. The latter approach involves the first protecting-group-free synthesis of spisulosine.
- Dinda, Subal Kumar,Das, Sajal Kumar,Panda, Gautam
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experimental part
p. 9304 - 9309
(2011/01/12)
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- Synthesis and antioxidant properties of an unnatural plasmalogen analogue bearing a trans O-vinyl ether linkage
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To assess the antioxidant behavior of trans-1, we first synthesized trans-allyl ether 4 by opening an (S)-glycildol derivative with an (E)-alk-2en-ol, and then produced the unnatural E-enol ether 1 by a stereoselective iridium(I)-catalyzed olefin isomerization. Natural cis-1 was preferentially degraded by HOCI and was more protective than trans-1 against lipid peroxidation Induced by a free-radical Initiator, demonstrating that the geometry of the 1-alkenyloxy bond participates In the antioxidant defensive role of 1.
- Lankalapalli, Ravi S.,Eckelkamp, Joseph T.,Sircar, Debajit,Ford, David A.,Subbaiah, Papasani V.,Bittman, Robert
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supporting information; experimental part
p. 2784 - 2787
(2009/12/05)
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- A stereoselective synthesis of dihydrosphingosine
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A highly enantioselective synthesis of D-(+)-erythro-dihydrosphingosine (sphinganine) as its triacetate derivative 10, starting from palmityl alcohol (3) and employing the Sharpless asymmetric dihydroxylation as the key step, is described.
- Fernandes, Rodney A.,Kumar, Pradeep
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p. 3447 - 3449
(2007/10/03)
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- Pheromone synthesis, CLXXV: Synthesis of koiganal I and II, the sex pheromone components of the webbing clothes moth
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Koiganal I [(E)-2-octadecenal (1)] and II [(2E,13Z)-2,13-octadecadienal (2)], the female-produced pheromone components of the webbing clothes moth (Tineola bisselliella), were synthesized. VCH Verlagsgesellschaft mbH, 1997.
- Takikawa, Hirosato,Takenaka, Motonobu,Mori, Kenji
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p. 139 - 140
(2007/10/03)
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- Synthesis of Sphingosine Relatives, XIV. A New Synthesis of Symbioramide, a Ca(++)-ATPase Activator from Symbiodinium sp.
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Symbioramide was synthesized from D-erythro-dihydrosphingosine (19) and (R,E)-2'-tert-butyldimethylsilyloxy-3'-octadecenoic acid (14), which was prepared from (E)-2-octadecen-1-ol (4) by employing the Sharpless asymmetric epoxidation.The (2S,2'S,3R,3'E)-isomer 28 of 1 was also synthesized to further confirm the structure of 1. - Key Words: Ca(++)-ATPase activator / Ceramides / Marine natural products / Sphingosines / Symbioramide
- Mori, Kenji,Uenishi, Keiji
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- Selective Isomerization of 1,2-Epoxyalkanes to Aldehydes with Lithium Dialkylamides
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Reaction of a variety of 1,2-epoxyalkanes with 2.5 equiv. of bulky metal amide - lithium 2,2,6,6-tetramethylpiperidide - affords the corresponding aldehydes exclusively in high yields; this is the first example of base-promoted isomerization of monosubstituted epoxides to aldehydes.
- Yanagisawa, Akira,Yasue, Katsutaka,Yamamoto, Hisashi
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p. 2103 - 2104
(2007/10/02)
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- Iodocyclofunctionalization of (E)-1-Trichloroacetimidoalk-2-enes. Synthesis of (+/-)-erythro-Sphinganine Triacetate
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From the iodocyclization of (E)-1-trichloroacetimido-octadec-2-ene, 5-iodo-4-pentadecyl-2-trichloromethyl-5,6-dihydro-4H-oxazine was unexpectedly obtained, whose structue was assigned from i.r. and (1)H n.m.r. spectra.The stereostructure of this oxazine was further confirmed by chemical evidence: thus, the compound was hydrolysed on silica gel to give 2-iodo-3-trichloroacetimido-octadecan-1-ol, and successive treatment with Amberlyst A 26 (CO3(2-) form) yielded cis-5-hydroxymethyl-4-pentadecyl-4,5-dihydro-oxazole, whose configuration was determined by (1)H n.m.r. data.Acidic hydrolysis of this oxazole and acetylation led to erythro-3-aminno-octadecane-1,2-diol triacetate.To ascertain definitively the structure of this triacetate, 3-trichloroacetamido-octadec-1-ene was cyclized, to yield 5-iodomethyl-4-pentadecyl-4,5-dihydro-oxazole as a 45:55 cis:trans mixture.After hydrolysis of the cis-isomer, treatment with Amberlyst A 26 (AcO(1-) form), and full acetylation, the aforementioned erythro-triacetate was obtained.Confirming the unequivocal assignment of the stereostructure of 5-iodo-4-pentadecyl-2-trichloromethyl-5,6-dihydro-4H-oxazine, its acidic cleavage gave 3-amino-1-iodo-octadecan-2-ol hydrochloride.By treatment of this salt with Amberlyst A 26 (AcO(1-) form), full acetylation of the product afforded (+/-)-erythro-sphinganine triacetate in good yield, contaminated with a minor amount of the regioisomeric 3-amino-octadecanediol-triacetate.
- Bongini, Alessandro,Cardillo, Giuliana,Orena, Mario,Sandri, Sergio,Tomasini, Claudia
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p. 1345 - 1350
(2007/10/02)
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- Directed Openings of 2,3-Epoxy Alcohols via Reactions with Isocyanates: Synthesis of (+)-erythro-Dihydrosphingosine
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Two methods for the synthesis of 2-(N-alkylamino) 1,3-diols from 2,3-epoxy alcohols are described.In one procedure (method A) an epoxyurethane (5, 8, 11, 14, 16) prepared from the corresponding epoxy alcohol by standard procedures is cyclized to a 2-oxazolidinone derivative (6, 9, 12, 15, 17) in 81-90percent yield by treatment with NaH in THF or NaOMe in MeOH.The second procedure (method B) involves treatment of the epoxy alcohol (4, 7, 10, 13, 24) with benzyl isocyanate, an NH3 synthetic equivalent, and NaH in THF at reflux.Hydrolysis of the crude isoxazolidinones by exposure to LiOH in EtOH at reflux smoothly affords 2-(N-benzylamino) 1,3-diols (22, 23, 30, 31) in 68-72percent overall yield.These procedures are highly regioselective; products resulting from intramolecular addition of the urethane nitrogen atom to the epoxide β-position were not detected.This methodology was applied to a short, highly stereoselective synthesis of (+)-erythro-dihydrosphingosine (26) from palmitic aldehyde ( 47-54percent overall yield).
- Roush, William R.,Adam, Michael A.
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p. 3752 - 3757
(2007/10/02)
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