- Manganese-promoted regioselective ring-opening of 2,3-epoxy acid derivatives: a new route to α-hydroxy acid derivatives
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A simple and general methodology directed towards the synthesis 3-aryl-2-hydroxy amides, or esters with total regioselectivity from the easily available 2,3-epoxy amides or esters, promoted by active manganese is described. Utilizing enantiopure epoxy amides as starting materials, the corresponding 3-aryl-2-hydroxy amides in enantiopure form are also available. Some synthetic applications of selected examples of 3-aryl-2-hydroxy carboxylic acid derivatives are shown. A mechanism has been proposed to explain this novel reaction.
- Concellon, Jose M.,Bernad, Pablo L.,Rodriguez-Solla, Humberto,Diaz, Pamela
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experimental part
p. 2178 - 2184
(2009/12/31)
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- Stereoselective Hydrogen Transfer Reactions Involving Acyclic Radicals. Tandem Substituted Tetrahydrofuran Formation and Stereoselective Reduction: Synthesis of the C17-C22 Subunit of Ionomycin
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The tandem iodoetherification reaction and stereoselective reduction of acyclic redicals has been used in the stereocontrolled synthesis of substituted tetrahydrofurans.Such a tetrahydrofuran intermediate is regioselectively cleaved using Me2BBr to reveal
- Guindon, Y.,Yoakim, C.,Gorys, V.,Ogilvie, W. W.,Delorme, D.,et al.
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p. 1166 - 1178
(2007/10/02)
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- STEREOSPECIFITY OF THE SPIN-SPIN COUPLING CONSTANTS AND CHEMICAL SHIFTS IN THE 13C NMR SPECTRA OF OXIRANECARBOXYLIC ESTERS
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It was established that the 3JCH spin-spin coupling constants and chemical shifts in the 13C NMR spectra of the cis and trans isomers of oxiranecarboxylic esters are stereospecific.The signals for the methyl groups of the cis isomer are 4-7 ppm upfield from the signals for the trans isomer.The 3JCH constant due to spin-spin coupling of the 2-CH3 (or 3-CH3) group and the proton at the C3 (or C2) atom amounts to 2 Hz for the cis isomer and is absent for the trans isomer.
- Alekseeva, L. M.,Bokanov, A. I.,Shvedov, V. I.,Sheinker, Yu. N.
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p. 1664 - 1666
(2007/10/02)
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- GENERAL RELATIONSHIPS IN THE OPENING OF THE OXIRANE RING DURING CLEAVAGE OF GLYCIDIC ACIDS
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By investigation of the decarboxylation of 2,3-epoxy derivatives of acids with various structures it was shown that contrary to the existing theory about the essential opening of the β (C-O) bond in the oxirane ring there are many structural types of 2,3-epoxypropionic acids, in which opening of the α (C-O) bond in the oxirane ring occurs during decarboxylation.It was also shown that these two possible reaction paths can also arise during the decarboxylation of one 2,3-epoxypropionic acid.On the basis of the obtained data a general relationship is developed for theopening of the oxirane ring during the decarboxylation of 2,3-epoxypropionic acids with any structure, and this makes it possible to predict the structure of the obtained carbonyl compound.
- Kuroyan, R. A.,Markosyan, A. I.,Engoyan, A. P.,Vartanyan, S. A.
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p. 1709 - 1714
(2007/10/02)
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