- Regiospecific Vinyl Phosphate/β-Keto Phosphonate Rearrangements Initiated by Halogen-Metal Exchange
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A new strategy has been developed for preparation of β-keto phosphonates via a halogen-metal exchange induced 1,3-phosphorus migration of 2-bromovinyl phosphates. These intermediates can be prepared through conversion of an α-bromo ketone to the appropriate enolate by reaction with strong base, or through conjugate addition to an α-bromo α,β-unsaturated ketone. In either case, trapping the resulting enolate by reaction with a dialkyl phosphorochloridate gives the 2-bromovinyl phosphate. Metalation can be accomplished upon treatment with n-BuLi, and rearrangement is facile once metalation has been achieved. Studies with isotopically labeled substrates have shown that this rearrangement is regiospecific, in contrast to vinyl phosphate/β-keto phosphonate rearrangements induced by strong base where regioisomeric products are sometimes obtained.
- Baker, Tracy J.,Wiemer, David F.
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- Synthesis of Di-, Tri-, and tetrasubstituted oxetanes by rhodium-catalyzed O-H insertion and C-C bond-forming cyclization
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Oxetanes offer exciting potential as structural motifs and intermediates in drug discovery and materials science. Here an efficient strategy for the synthesis of oxetane rings incorporating pendant functional groups is described. A wide variety of oxetane 2,2-dicarboxylates were accessed in high yields, including functionalized 3-/4-aryl-and alkyl-substituted oxetanes and fused oxetane bicycles. Enantioenriched alcohols provided enantioenriched oxetanes with complete retention of configuration. The oxetane products were further derivatized, while the ring was maintained intact, thus highlighting their potential as building blocks for medicinal chemistry.
- Davis, Owen A.,Bull, James A.
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supporting information
p. 14230 - 14234
(2015/02/19)
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- Enzymatic preparation of cis and trans-3-amino-4-hydroxytetrahydrofurans and cis-3-amino-4-hydroxypyrrolidines
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The lipase catalyzed resolution of cis and trans-3-amino-4-hydroxytetrahydrofurans and cis-3-amino-4-hydroxypyrrolidines have been studied. For all the heterocycles, the best enantioselectivity was obtained using Candida antarctica lipases A and B as cata
- Villar-Barro, ngela,Gotor, Vicente,Brieva, Rosario
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p. 5563 - 5568
(2015/01/09)
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- Enzymatic resolution of five membered heterocyclic bromohydrins
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The lipase catalyzed resolution of trans-3,4-tetrahydrofuran and pyrrolidine bromohydrins by acylation or hydrolysis of their acylated derivatives has been studied. For both heterocycles, the best enantioselectivity was obtained using Candida antarctica l
- Villar-Barro, Angela,Gotor, Vicente,Brieva, Rosario
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p. 694 - 698
(2013/07/11)
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- Process for halohydrin preparation
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A process for preparing a halohydrin of a water-miscible olefin comprising: reacting a water-miscible olefin in water with a compound of the formula (I) wherein R1 and R2 independently represent a branched or unbranched, substituted or unsubstituted, lower alkyl having from 1 to 5 carbons and X is a halogen, to thereby form the halohydrin of the water-miscible olefin.
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- Process for halohydrin preparation
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A process for preparing a halohydrin of a water-miscible olefin comprising: reacting a water-miscible olefin in water with a compound of the formula (I) wherein R1 and R2 independently represent a branched or unbranched, substituted or unsubstituted, lower alkyl having from 1 to 5 carbons and X is a halogen, to thereby form the halohydrin of the water-miscible olefin.
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- 6-(Hydroxyethyl)-2-(heterocyclylthio)-penem-3-carboxylates
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There is disclosed antibacterial compounds represented by the formula STR1 and pharmaceutically acceptable salts or pharmaceutically acceptable esters thereof, wherein: X represents oxygen, sulfur, STR2 wherein R is hydrogen, loweralkyl, acetate or methoxycarbonyl; Y is cis, trans or mixtures thereof and is selected from hydroxy, lower alkoxy, aminocarbamoyloxy, methoxycarbonylamino, lower alkylcarbonyloxy, lower alkylcarbonylamino and loweralkylsulfonylamino; and the wavy lines indicate cis, trans or mixtures thereof.
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