- Broad-spectrum catalysts for the ambient temperature anti-Markovnikov hydration of alkynes
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Anti-Markovnikov alkyne hydration provides a valuable route to aldehydes. Half-sandwich ruthenium complexes ligated by 5,5′-bis(trifluoromethyl)-2, 2′-bipyridine are remarkably active for this transformation. In the presence of 2 mol % metal, a wide range of functionalized aliphatic and aromatic alkynes are hydrated in high yield at ambient temperature. Alkyne hydration: Half-sandwich ruthenium complexes derived from 5,5′-bis(trifluoromethyl)- 2,2′-bipyridine show a high activity for the anti-Markovnikov hydration of terminal alkynes (see picture). A wide array of alkynes are efficiently hydrated to aldehydes using 2 mol % metal loadings at 25 °C within 8-24 h.
- Li, Le,Zeng, Mingshuo,Herzon, Seth B.
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supporting information
p. 7892 - 7895
(2014/08/05)
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- Synthesis of spiro-bisperoxyketals
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(Chemical Equation Presented) Syntheses of spirocyclic bis-1,2-dioxolanes, bis-1,2-dioxanes, and bis-1,2-dioxepanes are achieved through intramolecular ketalizations of hydroperoxy ketones or intramolecular alkylations of gem-dihydroperoxides. The spirope
- Ghorai, Prasanta,Dussault, Patrick H.,Hu, Chunhua
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supporting information; experimental part
p. 2401 - 2404
(2009/05/11)
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- A general bifunctional catalyst for the anti-Markovnikov hydration of terminal alkynes to aldehydes gives enzyme-like rate and selectivity enhancements
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A new, bifunctional catalyst for anti-Markovnikov hydration of terminal alkynes to aldehydes (6) allows practical room-temperature hydration of alkyl-substituted alkynes. Other outstanding features include near-quantitative aldehyde yields from both alkyl- and aryl-substituted alkynes and wide functional group tolerance. The uncatalyzed rate of alkyne hydration is measured for the first time, showing the enzyme-like rate and selectivity enhancements of aldehyde formation by 6. For aldehyde formation, an uncatalyzed rate -10 mol h-1 means a half-life >600 000, years. The catalyzed rate is up to 23.8 mol (mol 6)-1 h-1 and 10 000:1 ratio in favor of aldehyde. Changes in rate and selectivity induced by 6 are thus >2.4 × 1011 and 300 000, respectively. Copyright
- Grotjahn, Douglas B.,Lev, Daniel A.
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p. 12232 - 12233
(2007/10/03)
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- INTRAMOLECULAR N-ALKENYLNITRONE-ADDITIONS. REGIO- AND STEREOCHEMISTRY
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Efficient intramolecular cycloadditions of N-3-alkenyl- and N-4-alkenylnitrones proceed with opposite regioselection which is modified by dipolarophile-substituent effects.Polycyclic isoxazolidines are obtained in a highly stereocontrolled fashion, consistent with an endo-addition of the Z-nitrones.
- Oppolzer, W.,Siles, S.,Snowden, R. L.,Bakker, B. H.,Petrzilka, M.
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p. 3497 - 3509
(2007/10/02)
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- SOME FEATURES OF THE REARRANGEMENT OF TERTIARY ETHYNYLCARBINOLS IN THE PRESENCE OF POLYVANADIOORGANOSILOXANES
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The rearrangement of various tertiary ethynylcarbinols to α,β-unsaturated aldehydes, catalyzed by polyvanadioorganosiloxanes, was studied, and the activation parameters of the reaction were determined.The structures of the side products were established, and proposals were made about the mechanism of their formation.Additives which suppress the side reactions were found.As a result the yields of the unsaturated aldehydes were increased significantly.
- Erman, M. B.,Aul'chenko, I. S.,Kheifits, L. A.
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- Catalytic rearrangement
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Process for converting secondary and tertiary acetylenic carbinols to the corresponding alpha,beta-unsaturated carbonyl compounds by rearranging the carbinol with (trilower alkyl-, tricycloalkyl-, triaryl- or triarylalkyl-siloxy)-vanadium oxide catalyst in the presence of a silanol where either the vanadium oxide or the silanol contains a phenyl group substituted with at least one electron withdrawing group.
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