Rhodium(II)-Catalyzed C–H Functionalization of Electron-Deficient Methyl Groups
作者:Liangbing Fu、David M. Guptill、Huw M. L. Davies
DOI:10.1021/jacs.6b01941
日期:2016.5.11
Enantioselective C-H functionalization of relatively electron-deficient methyl sites was achieved with the combination of 2,2,2-trichloroethyl aryldiazoacetates and tetrakis(triarylcyclopropanecarboxylate) dirhodium catalysts. The substrate scope of the transformation was relatively broad, and C-H functionalization products were furnished with excellent levels of enantioselectivity. As a strategic
作者:Heinrich Becker、Marcos A. Soler、K. Barry Sharpless
DOI:10.1016/0040-4020(94)01021-q
日期:1995.1
The asymmetricdihydroxylation procedure (AD) is applied to a variety of polyenes. In many cases excellent regioselectivities are obtained. The observed selectivities are rationalized in terms of electronic and/or steric effects inherent to the substrate, superimposed on the substrate's favorable or unfavorable interactions with the binding pocket of the AD ligand. Surprisingly, for medium and large
Oxoketene dithioacetals as versatile synthons for alternative 1,3 to 1,11 carbonyl transpositions: A new polyene synthesis
作者:Malapaka Chandrasekharam、Chitoorthekkathil V Asokan、Hiriyakksnavar Ila、Hiriyakkanavar Junjappa
DOI:10.1016/s0040-4039(00)88875-9
日期:1990.1
strategy for 1,7 to 1,I1 carbonyI transpositions involving 1,2 addition of sodium borohydride or Grignard reagents to polyenyl oxoketene dithioacetals obtained by condensation of bis(methylthio)polyenals 1- with active methylene ketones, followed by borontrifluoride etherate catalyzed methanolysis of the resulting polyenyl carbinol acetals to give 1,n transposed polyene esters has been described.
Condensations of Crotonate Arsonium Ylide with Conjugated Carbonyl Compounds
作者:Cornelis Moorhoff
DOI:10.1055/s-1997-707
日期:——
Condensations of methyl 4-(triphenylarsoranylidene)-2-butenoate 1a and conjugated carbonylcompounds give 1,3-cyclohexadiene-1-carboxylates and/or acyclic trienes in superior yields compared to the condensations with the phosphonium analogue 1b. However, the reaction of 1a and ethyl 2-cyano-5-methyl-2,4-hexadienoate 7 gave a mixture of two diastereomeric trans-bisvinylcyclopropanecarboxylates 9.
Thermal rearrangement of ethers 3 generated in situ from hydroquinone 1 and conjugated polyen-ols 2 afforded 2,3-dihydrobenzofuranols 5, 8 and 10 with 1,3- and/or 3,5-shifts followed by acid-catalyzed intramolecular cyclization.