- A bidirectional SE′ strategy for 1,5- syn and 1,5- anti stereocontrol toward the synthesis of complex polyols
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Studies report a bidirectional SE′ strategy applicable for the stereocontrolled synthesis of nonracemic 1,5-syn and 1,5-anti diols and their derivatives. Nonracemic 1,3,2-diazaborolidine auxiliaries are incorporated by chemoselective tin-boron exchange to provide reactive allylic boranes. The convergent pathway utilizes sequential reactions with two aldehydes producing stereochemical outcomes from cyclic, closed, and open transition state preferences, respectively. Synthesis of fragment 16 of peloruside A is accomplished in four steps from readily available aldehydes 9 and 13.
- Williams, David R.,Claeboe, Christopher D.,Liang, Bo,Zorn, Nicolas,Chow, Nicholas S. C.
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supporting information; experimental part
p. 3866 - 3869
(2012/09/22)
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- THE CERIUM (III) MEDIATED REACTION OF TRIMETHYLSILYLMETHYL MAGNESIUM CHLORIDE WITH ESTERS AND LACTONES: THE EFFICIENT SYNTHESIS OF SOME FUNCTIONALISED ALLYLSILANES OF USE IN ANNULATION REACTIONS
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The use of cerium (III) chloride alters the chemoselectivity of the reaction of trimethylsilylmethyl magnesium chloride with ester-acetals and also greatly improves the efficiency of reaction with lactones.In addition it gives improved preparations of the useful intermediates (7), (13), (18), (20) and (22) and gives direct access to the valuable functionalised allylsilanes (1) to (3) of use in annulation reactions.
- Lee, Thomas V.,Channon, Julia A.,Cregg, Carmel,Porter, John R.,Roden, Frances S.,Yeoh, Helena T-L.
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p. 5877 - 5886
(2007/10/02)
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- DIRECT ACCESS TO FUNCTIONALISED ALLYLSILANES: THE CERIUM(III) MEDIATED GRIGNARD REACTION OF FUNCTIONALISED ESTERS AND LACTONES
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The use of cerium (III) chloride alters the chemoselectivity of the reaction of the Grignard reagent (1) with ester-acetals and also greatly improves the efficiency of reaction with lactones.In addition it gives improved preparations of the useful intermediates (8), (11) and (12) giving direct access to valuable functionalised allylsilanes of use in annulation reactions.
- Lee, Thomas V.,Porter, John R.,Roden, Frances S.
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p. 5009 - 5012
(2007/10/02)
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- TRIMETHYLENEMETHANE METAL COMPLEXES. PART1. SYNTHESIS OF RUTHENIUM, OSMIUM, RHODIUM, AND IRIDIUM COMPLEXES
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1--3-trimethylsilylprop-1-ene, available from 2-methylprop-2-en-1-ol, serves as a new entry into trimethylenemethane (tmm) metal complexes.Reaction with low-valent metal complexes affords the first tmm metal complexes of ruthenium, osmium, rhodium, and iridium: 4-tmm)> (M=Ru or Os), 4-tmm)>, 4-tmm)> (M=Rh or Ir), and 4-tmm)> (X=Cl, L=PPh3 or AsPh3; X=Br, L=PPh3).The desilylation of an η3-allyl intermediate rationalises the results and has been verified by the reaction of sodium fluoride with 3-CH2C(CH2SiMe3))CH2>Cl(CO)(PMe2Ph)2>BPH4 in aqueous methyl cyanide which gave the complex 4-tmm)>BPh4 in quantitative yield.N.m.r. data (1H, 13C-) are reported and variable-temperature 1H n.m.r. spin-magnetisation transfer experiments have been used to set a lower limit of ca. 90 kJ mol-1 for the activation energies for trimethylenemethane rotation.
- Jones, Michael D.,Kemmitt, Raymond D. W.,Platt, Andrew W. G.
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p. 1411 - 1418
(2007/10/02)
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- A Annulation Procedure for Methylenecyclopentanes
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A two step sequence converts certain cyclic enones to fused methylenecyclopentanes using the annulation reagent 2-chloromethyl-3-trimethylsilylpropene.
- Knapp, Spencer,O'Connor, Una,Mobilio, Dominick
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p. 4557 - 4560
(2007/10/02)
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