- Synthesis of 6-membered cyclic carbonates from 1,3-diols and low CO2 pressure: A novel mild strategy to replace phosgene reagents
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Low pressure carbon dioxide is used as the carbonation agent in a simple, safe and efficient procedure for the synthesis of 6-membered cyclic carbonates from 1,3-diols. Using readily available reagents and proceeding at room temperature, this route offers a novel mild alternative to phosgene derivatives.
- Gregory, Georgina L.,Ulmann, Marion,Buchard, Antoine
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p. 39404 - 39408
(2015/05/20)
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- 1,3-Diol synthesis via controlled, radical-mediated C-H functionalization
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The invention of a method for the synthesis of 1,3-diols from the corresponding alcohols is described, via controlled, radical-mediated C-H functionalization. The sequence described herein entails near quantitative conversion to the corresponding trifluoroethyl carbamate, followed by a variant of the Hofmann-Loffler-Freytag reaction, cyclization, and hydrolysis to provide the 1,3-diols. In addition to the 10 examples presented herein, the syntheses of four natural products are facilitated by this directed oxyfunctionalization. This methodology is demonstrated to be orthogonal to other known C-H oxidations. Finally, this sequence is efficient, practical, inexpensive, and scalable. Copyright
- Chen, Ke,Richter, Jeremy M.,Baran, Phil S.
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p. 7247 - 7249
(2008/12/21)
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- Thermolysis of a spiro-fused oxadiazoline: The carbonyl ylide-cyclic carbene-diradical sequence
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Thermolysis of spiro-fused oxadiazoline 1 in benzene led to loss of N2 to form a carbonyl ylide intermediate. Most of the ylide fragmented to acetone and 4-phenyl-1,3-dioxane-2-ylidene, which could be trapped with tert-butyl alcohol. In the absence of the trapping agent, the major pathway followed by the carbene was fragmentation to a diradical, 5-phenyl-2-oxa-1-oxo-1,5-pentanediyl. The latter diradical coupled to α-phenyl-δ-butyrolactone and decarboxylated to afford cyclopropylbenzene. Other products from the reaction were those of apparent insertion of the carbene into a C-H bond of the benzene solvent and into a C-H bond of acetone. Such reactions appear to be without precedent - alternative, non-carbene mechanisms are proposed.
- Merkley, Nadine,Warkentin, John
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p. 1187 - 1195
(2007/10/03)
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- The Cycloaddition of Heterocumulenes to Oxetanes in the Presence of Catalytic Amounts of Tetraphenylstibonium Iodide
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The cycloadditions of carbon dioxide, isocyanates and carbodiimides to oxetanes proceeded in the presence of catalytic amounts of tetraphenylstibonium iodide (1) under mild conditions, affording the corresponding six-membered heterocycles; 1,3-dioxan-2-ones, 1,3-oxazin-2-ones and 1,3-oxazin-2-imines in good yields, respectively.Moreover, the cycloaddition of 2-phenyloxetane proceeded via predominant ring-cleavage at substituted site.
- Fujiwara, Masahiro,Baba, Akio,Matsuda, Haruo
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p. 1659 - 1663
(2007/10/02)
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- Quantitative Correlation between Calculated Molecular Properties and Retention of a Series of Structurally Related Racemates on Cellulose Triacetate
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Racemic compounds cionsisting of an alicyclic six-membered ring with a phenyl group attached to the chiral carbon atom have been investigated.The chemical structure of the alicyclic part was varied systematically, in order to establish its influence on the separability of the racemates into their pure enantiomers on cellulose triacetate (CTA).Theoretical investigations, involving conformational analysis and charge distribution, have been undertaken to correlate structural features with chromatographic behaviour.For this class of compounds two major parameters governing the interaction with CTA are the rotational freedom of the bond to the phenyl group and thereby the relative ability to assume the flattest possible conformation, and a negatively charged neighbourhood of the chiral centre.
- Wolf, Romain M.,Francotte, Eric,Lohmann, Dieter
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p. 893 - 902
(2007/10/02)
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