Optically Active 4-Substituted 5-Nitropentan-2-ones: Valuable Chiral Building Blocks for the Stereocontrolled Construction of Spiro-Pyrazolone Scaffolds with Five Contiguous Stereogenic Centers
作者:Jiao Sun、Cuiping Jiang、Zhenghong Zhou
DOI:10.1002/ejoc.201501449
日期:2016.2
The application of readily available opticallyactive4-substituted5-nitropentan-2-ones as chiralbuildingblocks in the stereocontrolledconstruction of spiro-pyrazolonescaffolds was investigated. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (1 equiv.) opticallyactive4-substituted 5-nitropentan-4-ones exhibited excellent chiral inducing abilities in the diastereoselective cascade Michael/aldol
An efficient and highly diastereoselective synthesis of carbocyclic spiropyrazolones via one-pot sequential dual organo-silver catalyzed Michael-hydroalkylation reactions
作者:Khyati Shukla、Sadhna Shah、Nirmal K. Rana、Vinod K. Singh
DOI:10.1016/j.tetlet.2018.11.064
日期:2019.1
An economical approach for the diastereoselective synthesis of highly functionalized carbocyclic spiropyrazolone derivatives having one quaternary and two tertiary stereocenters along with one exocyclic double bond exploiting dual organo-silver sequential catalysis has been developed. The unified method to both cyclohexyl and cyclopentyl spirocompounds involves the reaction of γ- and β-nitroalkynes
Enantioselective aminocatalytic synthesis of tetrahydropyrano[2,3-c]pyrazoles via a domino Michael-hemiacetalization reaction with alkylidene pyrazolones
作者:Rajendra Maity、Subhas Chandra Pan
DOI:10.1039/c7ob02170d
日期:——
An enantioselectiveorganocatalytic domino Michael-hemiacetalization reaction between alkylidene pyrazolones and cyclic ketones/pentanal has been revealed. The fused tetrahydropyranopyrazole products having three contiguous stereocentres were obtained with perfect diastereoselectivities and in moderate to good yields with good to high enantioselectivities. Also, few synthetic transformations of the
Palladium‐Catalyzed Asymmetric [4+2] Cycloaddition of 2‐Methylidenetrimethylene Carbonate with Alkenes: Access to Chiral Tetrahydropyran‐Fused Spirocyclic Scaffolds
A palladium‐catalyzed asymmetric [4+2] cycloaddition of 2‐methylidenetrimethylene carbonate with alkenes derived from pyrazolones, indandione, or barbiturate has been successfully developed, affording pharmacologically interesting chiral tetrahydropyran‐fused spirocyclic scaffolds. The target compounds were generated in good to excellent yields and with high enantioselectivity (up to 99 % ee ). Furthermore
Organocatalyzed asymmetric tandem Michael-cyclization reaction of 4-benzylidene-3-methylpyrazol-5-ones and malononitrile: stereocontrolled construction of pyrano[2,3-c]pyrazole scaffold
作者:H.-X. Wang、L.-L. Wu、Y.-M. Wang、Z.-H. Zhou
DOI:10.1039/c5ra04356e
日期:——
An efficient approach for the stereocontrolled construction of pyrano[2,3-c]pyrazole scaffold has been developed. Under the catalysis of a bifunctionalsquaramide derived from (1R,2R)-1,2-diphenylethane-1,2-diamine, the asymmetric tandem Michael addition/cyclization reaction of 4-benzylidenepyrazol-5(4H)-ones and malononitrile proceeded efficiently to furnish the desired pyrano[2,3-c]pyrazoles in satisfactory
开发了一种有效的立体控制吡喃并[2,3- c ]吡唑支架的方法。在衍生自(1 R,2 R)-1,2-二苯乙烷-1,2-二胺的双官能方酰胺的催化下,4-苄叉基吡唑-5(4 H)-的不对称串联迈克尔加成/环化反应与丙二腈有效地进行,以令人满意的产率提供了所需的吡喃并[2,3- c ]吡唑类,并具有高水平的对映体选择性(至多99%ee)。