- Synthesis of the conjugated tetraene acid side chain of mycolactone e by Suzuki-Miyaura cross-coupling reaction of alkenyl boronates
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The conjugated tetraene acid side chain of mycolactone E has been synthesized by the cross-coupling reaction of a trisubstituted triene bromide with a trisubstituted alkenyl boronate catalyzed by Pd(OAc)2-Aphos-Y under mildly basic conditions [K3PO4·3H 2O, H2O, tetrahydrofuran (THF), 35 °C, 18 h]. The conjugated tetraene product was obtained in 85 % yield without geometrical isomer(s) under the catalytic conditions. These results demonstrated that the coupling of alkenyl halides with alkenyl boronates catalyzed by Pd(OAc) 2-Aphos-Y in combination with CuI-catalyzed regio- and stereoselective alkyne borylation offers an efficient synthetic tool for accessing conjugated polyene molecules. Gently united: Conjugate polyenes possessing trisubstituted double bond(s) are synthesized from trisubstituted alkenyl halides and trisubstituted boronates in high yields under the catalysis of the hemilabile P,O ligand Aphos-Y and Pd(OAc)2 in the presence of K3PO4·3H2O (3 equiv.) and H2O (18 equiv.) in tetrahydrofuran (THF) at 35°C. The product is free of geometric isomers. Copyright
- Wang, Yuan,Dai, Wei-Min
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supporting information
p. 323 - 330
(2014/01/23)
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- Highly enantioselective Rh-Catalyzed Alkenylation of imines: Synthesis of Chiral Allylic Amines via Asymmetric addition of Potassium Alkenyltrifluoroborates to N-Tosyl imines
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For the first time, simple N-tosyl aryl aldimines, prepared from the condensation of tosyl amide and aromatic aldehydes, can be used as substrates in the rhodium catalyzed 1,2- addition reaction using alkenylboron nucleophiles. In the presence of 1.5 mol % of [RhCl(1e)]2, enantioselective addition of various potassium alkenyltrifluoroborates to aryl aldimines furnished the corresponding chiral allylic amines in 73-96% yield and 72->99.5% ee. Notably, this method efficiently provides the di-, tri-, and tetrasubstituted allylic N-tosyl amines with high asymmetric induction.
- Gopula, Balraj,Chiang, Chien-Wei,Lee, Way-Zen,Kuo, Ting-Shen,Wu, Ping-Yu,Henschke, Julian P.,Wu, Hsyueh-Liang
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p. 632 - 635
(2014/04/03)
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- Process for preparing beta-L-2'deoxy-thymidine
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The present invention relates to a new, essentially four-step process for preparing beta-L-2′-deoxy-thymidine starting from L-arabinose. The process according to the invention is particularly important for mass production of beta-L-2′-deoxy-thymidine.
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- REACTION OF α,β-DIBROMO CARBOXYLIC ESTERS WITH HYDRAZINES
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In the reaction of unsymmetrical disubstituted hydrazines with α,β-dibromo carboxylic esters, in contrast to the analogous reactions of alkoxyamines, it is not possible to obtain the corresponding N-aminoaziridines.As a result of the transformations vario
- Prosyanik, A. V.,Markov, V. I.,Bondarenko, S. V.
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p. 2171 - 2174
(2007/10/02)
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