Asymmetric Addition of Arylboronic Acids to Cumulene Derivatives Catalyzed by Axially Chiral N-Heterocyclic Carbene-Pd2+ Complexes
作者:Zhen Liu、Peng Gu、Min Shi
DOI:10.1002/chem.201100703
日期:2011.5.16
Cumulene+carbene=chirality! Asymmetricadditions of boronic acids to cumulenederivatives, catalyzed by an N‐heterocyclic carbene–palladium complex, provide the desired allenic products in good to excellent yields and moderate to good enantioselectivities. These optically active allenic adducts can be further transformed to useful chiral products in good yields and with an intact chirality (see scheme)
Triflic imide-catalyzed cascade cycloaddition and Friedel–Crafts reaction of diarylvinylidenecyclopropanes with ethyl 5,5-diarylpenta-2,3,4-trienoate
作者:Wei Li、Min Shi
DOI:10.1039/b903965a
日期:——
Triflic imide-catalyzed cascade cycloaddition and FriedelâCrafts reaction of diarylvinylidenecyclopropanes with ethyl 5,5-diarylpenta-2,3,4-trienoates provided a variety of novel polycyclic ester derivatives in moderate to good yields under mild conditions.
Reaction of bromine with phenyl-substituted tertiary alcohols
作者:Douglas W. Grant、Roy Shilton
DOI:10.1039/p19740000135
日期:——
The reaction between bromine and 1,1-diphenylalkan-1-ols is shown to proceed by dehydration to an alkene, followed in aqueous acetic acid by formation of a bromohydrin which may then rearrange to a ketone. A number of new bromohydrins and bromoalkenes have been prepared.
Synthesis and reactions of allenic phosphonium salts and ylides
作者:Kenneth Wayne Ratts、R. D. Partos
DOI:10.1021/ja01050a031
日期:1969.10
FimZ Binds the<i>Salmonella typhimurium fimA</i>Promoter Region and May Regulate Its Own Expression with FimY
作者:Kuang-sheng Yeh、Juliette K. Tinker、Steven Clegg
DOI:10.1111/j.1348-0421.2002.tb02670.x
日期:2002.1
AbstractThe FimZ protein, an activator of FimA production in Salmonella typhimurium, acts in conjunction with FimY to facilitate the expression of type 1 fimbriae. The predicted amino acid sequence of FimZ suggests that this protein may be a DNA‐binding protein related to BvgA, a sensory regulator of virulence gene expression in Bordetella pertussis. Purification of FimZ following overexpression of the protein by a strong inducible promoter and gel mobility shift assays confirm that FimZ is a 25‐kDa polypeptide that binds to the promoter region of fimA. The region of DNA protected from DNase I digestion by FimZ binding is located between 47 and 98 nucleotides upstream from the fimA transcription initiation site. This region possesses a pair of 7‐base pair tandem repeats, of which at least one is necessary for FimZ binding. One copy of the 7‐base pair sequence is also located in the fimZ promoter region. In addition, expression from a fimZ‐lacZ reporter construct confirms that FimZ plays a role in its own expression. Both FimZ and FimY are required for high‐level expression of FimZ, which suggests that these two fimbrial proteins are involved in regulating both FimA and FimZ.