- The Total Synthesis of Epothilone D as a Yardstick for Probing New Methodologies
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Here, a concise and highly convergent synthesis of epothilone D was investigated, relying on fragments of equal complexity that could be prepared in gram scale quantities. The strategy to construct the fragments includes the use of a previously reported enantiospecific zinc-catalyzed cross-coupling of an α-hydroxy ester triflate with a Grignard reagent, the application of a hydroboration/boron–magnesium exchange sequence for the rapid construction of the Z-substituted trisubstituted double bond present in the natural product, and a Noyori-type hydrogenation to install the β-hydroxy ester moiety of the southern part. The key to success is the diastereoselective head-to-tail macrolactonization by an intramolecular addition of the corresponding ω-alkynyl-substituted carboxylic acids to construct a new stereocenter in the macrocyclic core structure in one single step.
- Haydl, Alexander M.,Breit, Bernhard
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supporting information
p. 541 - 545
(2017/01/18)
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- Reactions of hydroxylamines with ethyl cyanoformate. Preparation of aminonitrones and their synthetic applications
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The reaction of hydroxylamines with ethyl cyanoformate 1 leads to the formation of carbethoxyamino nitrones. 2. UV spectroscopy provided information that suggested the nitrone structure for these compounds in solution. X-ray analysis of 2a confirmed that it exists entirely in the nitrone form in the solid state. These nitrones are shown to be excellent starting materials for a variety of nitrogen containing compounds, namely, imidazoles, benzimidazoles, benzimidazolones, oxadiazolones, N-arylamidines and quinoxalone.
- Branco,Prabhakar,Lobo,Williams
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p. 6335 - 6360
(2007/10/02)
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- TANDEM ORGANOMETALLIC ADDITION REACTIONS TO N-METHOXY-UREAS AND URETHANES IN THE PREPARATION OF UNSYMMETRICAL AND SYMMETRICAL KETONES
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The use of novel reagents 1a-c for the synthesis of ketones in a one pot reaction is described.An interesting leaving group effect was discovered in the fragmentation of the proposed complexes 2 to the intermediate N-methoxyamides 3.
- Hlasta, Dennis J.,Court, John J.
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p. 1773 - 1776
(2007/10/02)
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