Hormonal control of a gene encoding a putative PDR5-like ABC transporter in periwinkle
摘要:
ATP binding cassette (ABC) transporters retain increasing attention since their implication in multidrug resistance has been demonstrated in several prokaryotic and eukaryotic cells. Many ARC proteins are known in various organisms but only few in higher plants. We report here on the characterization of a partial 955 bp clone (Cr-ABC1) isolated from a Catharanthus roseus cDNA library, which shows high homology (65% identity) with the TUR2 cDNA previously isolated from the water lens Spirodela polyrrhiza. Accumulation of Cr-ABC1 transcripts in cultured C. roseus cells was enhanced by cytokinin or methyl jasmonate addition to, or auxin suppression from the culture medium. In whole plants, the gene was mainly expressed in flowers.
A novel protocol for the synthesis of α-aryl nitriles has been successfully achieved via a copper-catalyzed cyanation of N-tosylhydrazones employing thiocyanate as the source of cyanide. The features of this method include a convenient operation, readily available substrates, low-toxicity thiocyanate salts, and a broad substrate scope.
Enantioseparation of nitriles (up to 92 % ee) and sulfoxides (up to 98 % ee) by inclusion crystallization with chiral organic salts of 4‐hydroxybenzoic acids and a chiral primary amine derived from l‐phenylalanine is described. This is the first example of the direct enantioseparation of aromatic nitriles without other functional groups.
Selective α‐Monomethylation by an Amine‐Borane/
<i>N</i>
,
<i>N</i>
‐Dimethylformamide System as the Methyl Source
作者:Hui‐Min Xia、Feng‐Lian Zhang、Tian Ye、Yi‐Feng Wang
DOI:10.1002/anie.201804794
日期:2018.9.3
A new and practical α‐monomethylation strategy using an amine‐borane/N,N‐dimethylformamide (R3N‐BH3/DMF) system as the methyl source was developed. This protocol has been found to be effective in the α‐monomethylation of arylacetonitriles and arylacetamides. Mechanistic studies revealed that the formyl group of DMF delivered the carbon and one hydrogen atoms of the methyl group, and R3N‐BH3 donated
Enantioselective Construction of Quaternary Stereogenic Carbon Atoms by the Lewis Base Catalyzed Additions of Silyl Ketene Imines to Aldehydes
作者:Scott E. Denmark、Tyler W. Wilson、Matthew T. Burk
DOI:10.1002/chem.201403342
日期:2014.7.21
the aldol addition reaction. In the presence of SiCl4 and the catalytic action of a chiral phosphoramide, silyl ketene imines undergo extremely rapid and high yielding addition to a wide variety of aromatic aldehydes with excellent diastereo‐ and enantioselectivity. Of particular note are the high yields and selectivities obtained from electron‐rich, electron‐poor, and hindered aldehydes. Linear aliphatic